Science.gov

Sample records for direct detection constraints

  1. Forecast constraints on inflation from combined CMB and gravitational wave direct detection experiments

    SciTech Connect

    Kuroyanagi, Sachiko; Gordon, Christopher; Silk, Joseph; Sugiyama, Naoshi

    2010-04-15

    We study how direct detection of the inflationary gravitational wave background constrains inflationary parameters and complements CMB polarization measurements. The error ellipsoids calculated using the Fisher information matrix approach with Planck and the direct detection experiment, Big Bang Observer (BBO), show different directions of parameter degeneracy, and the degeneracy is broken when they are combined. For a slow-roll parametrization, we show that BBO could significantly improve the constraints on the tensor-to-scalar ratio compared with Planck alone. We also look at a quadratic and a natural inflation model. In both cases, if the temperature of reheating is also treated as a free parameter, then the addition of BBO can significantly improve the error bars. In the case of natural inflation, we find that the addition of BBO could even partially improve the error bars of a cosmic variance-limited CMB experiment.

  2. Derivation of the anisotropy profile, constraints on the local velocity dispersion, and implications for direct detection

    SciTech Connect

    Hunter, Daniel R.

    2014-02-01

    We study the implications of a pseudo-phase-space density power-law for the anisotropy profile of a Milky Way-like dark matter halo. Requiring that the anisotropy parameter does not take non-physical values within the virial radius places a maximum value on the local radial velocity dispersion. For a plausible range of halo parameters, it is possible to take a local total velocity dispersion of up to about 300 km/s. Making this choice uniquely specifies the anisotropy and dispersion profiles. We introduce a way to model the local velocity distribution that incorporates this anisotropy and study the impact on direct detection.

  3. Dark matter direct detection constraints on the minimal supersymmetric standard model and implications for LHC Higgs boson searches

    SciTech Connect

    Cao, Junjie; Hikasa, Ken-ichi; Wang, Wenyu; Yang, Jin Min; Yu, Li-Xin

    2010-09-01

    Assuming the lightest neutralino solely composes the cosmic dark matter, we examine the constraints of the CDMS-II and XENON100 dark matter direct searches on the parameter space of the minimal supersymmetric standard model (MSSM) Higgs sector. We find that the current CDMS-II/XENON100 limits can exclude some of the parameter space which survive the constraints from the dark matter relic density and various collider experiments. We also find that in the currently allowed parameter space, the charged Higgs boson is hardly accessible at the LHC for an integrated luminosity of 30 fb{sup -1}, while the neutral non-SM (standard model) Higgs bosons (H,A) may be accessible in some allowed region characterized by a large {mu}. The future XENON100 (6000 kg-days exposure) will significantly tighten the parameter space in case of nonobservation of dark matter.

  4. Search times with arbitrary detection constraints

    NASA Astrophysics Data System (ADS)

    Campos, Daniel; Bartumeus, Frederic; Méndez, Vicenç

    2013-08-01

    Random encounters in space are central to describing diffusion-limited reactions, animal foraging, search processes, and many other situations in nature. These encounters, however, are often constrained by the capacity of the searcher to detect and/or recognize its target. This can be due to limited binding and perception abilities of the searcher or hiding and avoiding mechanisms used by the target. Hence detection failure upon passage over the target location turns the process into an n-passage problem, with n being random. Here we provide a general description of this detection problem for arbitrary dimensions and arbitrary detection constraints. The mean detection time (MDT) for a random searcher embedded in a sea of homogeneously distributed targets is obtained as a function of the target density ρ, the size domain L, and the effective detection distance a. While the scaling with ρ and L is found to be universal and equivalent to that found for the corresponding first-passage problem, the scaling of the MDT on a depends on the specific detection mechanism considered.

  5. Predictive directional compensator for systems with input constraints.

    PubMed

    Haeri, Mohammad; Aalam, Nima

    2006-07-01

    Nonlinearity caused by actuator constraint plays a destructive role in the overall performance of a control system. A model predictive controller can handle the problem by implementing a constrained optimization algorithm. Due to the iterative nature of the solution, however, this requires high computation power. In the present work we propose a new method to approach the problem by separating the constraint handling from the predictive control job. The input constraint effects are dealt with in a newly defined component called a predictive directional compensator, which works based on the directionality and predictive concepts. Through implementation of the proposed method, the computational requirement is greatly reduced with the least degradation of the closed-loop performance. Meanwhile, a new characteristic matrix has been defined by which directionality of SISO as well as nonminimum phase systems can be determined.

  6. Directional constraint of endpoint force emerges from hindlimb anatomy.

    PubMed

    Bunderson, Nathan E; McKay, J Lucas; Ting, Lena H; Burkholder, Thomas J

    2010-06-15

    Postural control requires the coordination of force production at the limb endpoints to apply an appropriate force to the body. Subjected to horizontal plane perturbations, quadruped limbs stereotypically produce force constrained along a line that passes near the center of mass. This phenomenon, referred to as the force constraint strategy, may reflect mechanical constraints on the limb or body, a specific neural control strategy or an interaction among neural controls and mechanical constraints. We used a neuromuscular model of the cat hindlimb to test the hypothesis that the anatomical constraints restrict the mechanical action of individual muscles during stance and constrain the response to perturbations to a line independent of perturbation direction. In a linearized neuromuscular model of the cat hindlimb, muscle lengthening directions were highly conserved across 10,000 different muscle activation patterns, each of which produced an identical, stance-like endpoint force. These lengthening directions were closely aligned with the sagittal plane and reveal an anatomical structure for directionally constrained force responses. Each of the 10,000 activation patterns was predicted to produce stable stance based on Lyapunov stability analysis. In forward simulations of the nonlinear, seven degree of freedom model under the action of 200 random muscle activation patterns, displacement of the endpoint from its equilibrium position produced restoring forces, which were also biased toward the sagittal plane. The single exception was an activation pattern based on minimum muscle stress optimization, which produced destabilizing force responses in some perturbation directions. The sagittal force constraint increased during simulations as the system shifted from an inertial response during the acceleration phase to a viscoelastic response as peak velocity was obtained. These results qualitatively match similar experimental observations and suggest that the force

  7. Remember judgments and the constraint of direct experience.

    PubMed

    Stoettinger, Elisabeth; Kaiser, Wolfgang; Perner, Josef

    2009-09-01

    The most direct assessment of episodic memory is provided by Remember versus Know judgments of recalled or recognised items. We investigate whether Remember judgments reflect episodic memories as a re-experience of formerly experienced events (mental time travel). If they do, they must obey the direct experience constraint: only directly experienced events can be re-experienced but not when the event is known through indirectly conveyed information. In two Experiments participants saw simple events in Power Point, e.g. a car exploding. In the direct experience condition these events were directly perceived. In three further conditions information about the object (particular car), the kind of event (explosion), or both were verbally conveyed. After controlling for a potential encoding specificity effect in Experiment 1, the frequency of Remember judgments was twice as high in the direct experience condition than in the other three conditions. This suggests that Remember judgments are--at least to some degree--subject to the direct experience constraint. PMID:18987880

  8. Methodological Constraints for Detecting the Modality Effect

    ERIC Educational Resources Information Center

    Schoor, Cornelia; Bannert, Maria; Jahn, Verena

    2011-01-01

    Introduction: The aim of our research was to investigate the modality effect in more detail by measuring it in a direct way. Two studies were conducted using the same subject and material. Method: Computer-based learning material was presented on several screens, each containing a short text and a picture. Modality was varied by presenting written…

  9. Plasma dark matter direct detection

    SciTech Connect

    Clarke, J.D.; Foot, R. E-mail: rfoot@unimelb.edu.au

    2016-01-01

    Dark matter in spiral galaxies like the Milky Way may take the form of a dark plasma. Hidden sector dark matter charged under an unbroken U(1)' gauge interaction provides a simple and well defined particle physics model realising this possibility. The assumed U(1)' neutrality of the Universe then implies (at least) two oppositely charged dark matter components with self-interactions mediated via a massless 'dark photon' (the U(1)' gauge boson). In addition to nuclear recoils such dark matter can give rise to keV electron recoils in direct detection experiments. In this context, the detailed physical properties of the dark matter plasma interacting with the Earth is required. This is a complex system, which is here modelled as a fluid governed by the magnetohydrodynamic equations. These equations are numerically solved for some illustrative examples, and implications for direct detection experiments discussed. In particular, the analysis presented here leaves open the intriguing possibility that the DAMA annual modulation signal is due primarily to electron recoils (or even a combination of electron recoils and nuclear recoils). The importance of diurnal modulation (in addition to annual modulation) as a means of probing this kind of dark matter is also emphasised.

  10. DIRECT IMAGING CONSTRAINTS ON THE PUTATIVE EXOPLANET 14 Her C

    SciTech Connect

    Rodigas, Timothy J.; Males, Jared R.; Hinz, Philip M.; Knox, Russell P.; Mamajek, Eric E.

    2011-05-01

    We present results of deep direct imaging of the radial velocity (RV) planet-host star 14 Her (=GJ 614, HD 145675), obtained in the L' band with the Clio-2 camera and the MMT adaptive optics system. This star has one confirmed planet and an unconfirmed outer companion, suggested by residuals in the RV data. The orbital parameters of the unconfirmed object are not well constrained since many mass/semimajor axis configurations can fit the available data. The star has been directly imaged several times, but none of the campaigns has ruled out sub-stellar companions. With {approx}2.5 hr of integration, we rule out at 5{sigma} confidence {approx}>18 M{sub J} companions beyond {approx}25 AU, based on the Baraffe et al. COND mass-luminosity models. Combining our detection limits with fits to the RV data and analytic dynamical analysis, we constrain the orbital parameters of 14 Her c to be 3 {approx}< m/M{sub J} {approx}<42, 7 {approx}< a/AU {approx}<25, and e {approx}< 0.5. A wealth of information can be obtained from RV/direct imaging overlap, especially with deep imaging as this work shows. The collaboration between RV and direct imaging will become more important in the coming years as the phase space probed by each technique converges. Future studies involving RV/imaging overlap should be sure to consider the effects of a potential planet's projected separation, as quoting limits assuming face-on orientation will be misleading.

  11. Constraints on the detection of cryovolcanic plumes on Europa

    NASA Astrophysics Data System (ADS)

    Quick, Lynnae C.; Barnouin, Olivier S.; Prockter, Louise M.; Patterson, G. Wesley

    2013-09-01

    Surface venting is a common occurrence on several outer solar system satellites. Spacecraft have observed plumes erupting from the geologically young surfaces of Io, Triton and Enceladus. Europa also has a relatively young surface and previous studies have suggested that cryovolcanic eruptions may be responsible for the production of low-albedo deposits surrounding lenticulae and along triple band margins and lineae. Here, we have used the projected thicknesses of these deposits as constraints to determine the lifetimes of detectable cryovolcanic plumes that may have emplaced them. In an effort to explore the feasibility of detection of the particle component of plumes by spacecraft cameras operating at visible wavelengths, we present a conservative model to estimate plume characteristics such as height, eruption velocity, and optical depth under a variety of conditions. We find that cryovolcanic plumes on Europa are likely to be fairly small in stature with heights between 2.5 and 26 km, and eruption velocities between 81 and 261 m/s, respectively. Under these conditions and assuming that plumes are products of steady eruptions with particle radii of 0.5 μm, our model suggests that easily detectable plumes will have optical depths, τ, greater than or equal to 0.04, and that their lifetimes may be no more than 300,000 years. Plume detection may be possible if high phase angle limb observations and/or stereo imaging of the surface are undertaken in areas where eruptive activity is likely to occur. Cameras with imaging resolutions greater than 50 m/pixel should be used to make all observations. Future missions could employ the results of our model in searches for plume activity at Europa.

  12. Global limits and interference patterns in dark matter direct detection

    SciTech Connect

    Catena, Riccardo; Gondolo, Paolo

    2015-08-13

    We compare the general effective theory of one-body dark matter nucleon interactions to current direct detection experiments in a global multidimensional statistical analysis. We derive exclusion limits on the 28 isoscalar and isovector coupling constants of the theory, and show that current data place interesting constraints on dark matter-nucleon interaction operators usually neglected in this context. We characterize the interference patterns that can arise in dark matter direct detection from pairs of dark matter-nucleon interaction operators, or from isoscalar and isovector components of the same operator. We find that commonly neglected destructive interference effects weaken standard direct detection exclusion limits by up to one order of magnitude in the coupling constants.

  13. Direct and indirect detection of dissipative dark matter

    SciTech Connect

    Fan, JiJi; Katz, Andrey; Shelton, Jessie E-mail: katz.andrey@gmail.com

    2014-06-01

    We study the constraints from direct detection and solar capture on dark matter scenarios with a subdominant dissipative component. This dissipative dark matter component in general has both a symmetric and asymmetric relic abundance. Dissipative dynamics allow this subdominant dark matter component to cool, resulting in its partial or total collapse into a smaller volume inside the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion compared to that of normal cold dark matter. We first show that these features considerably relax the limits from direct detection experiments on the couplings between standard model (SM) particles and dissipative dark matter. On the other hand, indirect detection of the annihilation of the symmetric dissipative dark matter component inside the Sun sets stringent and robust constraints on the properties of the dissipative dark matter. In particular, IceCube observations force dissipative dark matter particles with mass above 50 GeV to either have a small coupling to the SM or a low local density in the solar system, or to have a nearly asymmetric relic abundance. Possible helioseismology signals associated with purely asymmetric dissipative dark matter are discussed, with no present constraints.

  14. Robust infrared small target detection via non-negativity constraint-based sparse representation.

    PubMed

    Wan, Minjie; Gu, Guohua; Qian, Weixian; Ren, Kan; Chen, Qian

    2016-09-20

    Infrared (IR) small target detection is one of the vital techniques in many military applications, including IR remote sensing, early warning, and IR precise guidance. Over-complete dictionary based sparse representation is an effective image representation method that can capture geometrical features of IR small targets by the redundancy of the dictionary. In this paper, we concentrate on solving the problem of robust infrared small target detection under various scenes via sparse representation theory. First, a frequency saliency detection based preprocessing is developed to extract suspected regions that may possibly contain the target so that the subsequent computing load is reduced. Second, a target over-complete dictionary is constructed by a varietal two-dimensional Gaussian model with an extent feature constraint and a background term. Third, a sparse representation model with a non-negativity constraint is proposed for the suspected regions to calculate the corresponding coefficient vectors. Fourth, the detection problem is skillfully converted to an l1-regularized optimization through an accelerated proximal gradient (APG) method. Finally, based on the distinct sparsity difference, an evaluation index called sparse rate (SR) is presented to extract the real target by an adaptive segmentation directly. Large numbers of experiments demonstrate both the effectiveness and robustness of this method. PMID:27661588

  15. Goal Directed Model Inversion: Learning Within Domain Constraints

    NASA Technical Reports Server (NTRS)

    Colombano, Silvano P.; Compton, Michael; Raghavan, Bharathi; Friedland, Peter (Technical Monitor)

    1994-01-01

    Goal Directed Model Inversion (GDMI) is an algorithm designed to generalize supervised learning to the case where target outputs are not available to the learning system. The output of the learning system becomes the input to some external device or transformation, and only the output of this device or transformation can be compared to a desired target. The fundamental driving mechanism of GDMI is to learn from success. Given that a wrong outcome is achieved, one notes that the action that produced that outcome "would have been right if the outcome had been the desired one." The algorithm makes use of these intermediate "successes" to achieve the final goal. A unique and potentially very important feature of this algorithm is the ability to modify the output of the learning module to force upon it a desired syntactic structure. This differs from ordinary supervised learning in the following way: in supervised learning the exact desired output pattern must be provided. In GDMI instead, it is possible to require simply that the output obey certain rules, i.e., that it "make sense" in some way determined by the knowledge domain. The exact pattern that will achieve the desired outcome is then found by the system. The ability to impose rules while allowing the system to search for its own answers in the context of neural networks is potentially a major breakthrough in two ways: (1) it may allow the construction of networks that can incorporate immediately some important knowledge, i.e., would not need to learn everything from scratch as normally required at present; and (2) learning and searching would be limited to the areas where it is necessary, thus facilitating and speeding up the process. These points are illustrated with examples from robotic path planning and parametric design.

  16. Goal Directed Model Inversion: Learning Within Domain Constraints

    NASA Technical Reports Server (NTRS)

    Colombano, Silvano P.; Compton, Michael; Raghavan, Bharathi; Lum, Henry, Jr. (Technical Monitor)

    1994-01-01

    Goal Directed Model Inversion (GDMI) is an algorithm designed to generalize supervised learning to the case where target outputs are not available to the learning system. The output of the learning system becomes the input to some external device or transformation, and only the output of this device or transformation can be compared to a desired target. The fundamental driving mechanism of GDMI is to learn from success. Given that a wrong outcome is achieved, one notes that the action that produced that outcome "would have been right if the outcome had been the desired one." The algorithm makes use of these intermediate "successes" to achieve the final goal. A unique and potentially very important feature of this algorithm is the ability to modify the output of the learning module to force upon it a desired syntactic structure. This differs from ordinary supervised learning in the following way: in supervised learning the exact desired output pattern must be provided. In GDMI instead, it is possible to require simply that the output obey certain rules, i.e., that it "make sense" in some way determined by the knowledge domain. The exact pattern that will achieve the desired outcome is then found by the system. The ability to impose rules while allowing the system to search for its own answers in the context of neural networks is potentially a major breakthrough in two ways: 1) it may allow the construction of networks that can incorporate immediately some important knowledge, i.e. would not need to learn everything from scratch as normally required at present, and 2) learning and searching would be limited to the areas where it is necessary, thus facilitating and speeding up the process. These points are illustrated with examples from robotic path planning and parametric design.

  17. Direct electrical detection of DNA synthesis

    PubMed Central

    Pourmand, Nader; Karhanek, Miloslav; Persson, Henrik H. J.; Webb, Chris D.; Lee, Thomas H.; Zahradníková, Alexandra; Davis, Ronald W.

    2006-01-01

    Rapid, sequence-specific DNA detection is essential for applications in medical diagnostics and genetic screening. Electrical biosensors that use immobilized nucleic acids are especially promising in these applications because of their potential for miniaturization and automation. Current DNA detection methods based on sequencing by synthesis rely on optical readouts; however, a direct electrical detection method for this technique is not available. We report here an approach for direct electrical detection of enzymatically catalyzed DNA synthesis by induced surface charge perturbation. We discovered that incorporation of a complementary deoxynucleotide (dNTP) into a self-primed single-stranded DNA attached to the surface of a gold electrode evokes an electrode surface charge perturbation. This event can be detected as a transient current by a voltage-clamp amplifier. Based on current understanding of polarizable interfaces, we propose that the electrode detects proton removal from the 3′-hydroxyl group of the DNA molecule during phosphodiester bond formation. PMID:16614066

  18. Median recoil direction as a WIMP directional detection signal

    SciTech Connect

    Green, Anne M.; Morgan, Ben

    2010-03-15

    Direct detection experiments have reached the sensitivity to detect dark matter weakly interacting massive particles (WIMPs). Demonstrating that a putative signal is due to WIMPs, and not backgrounds, is a major challenge, however. The direction dependence of the WIMP scattering rate provides a potential WIMP 'smoking gun'. If the WIMP distribution is predominantly smooth, the Galactic recoil distribution is peaked in the direction opposite to the direction of Solar motion. Previous studies have found that, for an ideal detector, of order 10 WIMP events would be sufficient to reject isotropy, and rule out an isotropic background. We examine how the median recoil direction could be used to confirm the WIMP origin of an anisotropic recoil signal. Specifically, we determine the number of events required to confirm the direction of solar motion as the median inverse recoil direction at 95% confidence. We find that for zero background 31 events are required, a factor of {approx}2 more than are required to simply reject isotropy. We also investigate the effect of a nonzero isotropic background. As the background rate is increased the number of events required increases, initially fairly gradually and then more rapidly, once the signal becomes subdominant. We also discuss the effect of features in the speed distribution at large speeds, as found in recent high resolution simulations, on the median recoil direction.

  19. PROJECTED CONSTRAINTS ON THE COSMIC (SUPER)STRING TENSION WITH FUTURE GRAVITATIONAL WAVE DETECTION EXPERIMENTS

    SciTech Connect

    Sanidas, Sotirios A.; Battye, Richard A.; Stappers, Benjamin W. E-mail: rbattye@jb.man.ac.uk

    2013-02-10

    We present projected constraints on the cosmic string tension, G{mu}/c {sup 2}, that could be achieved by future gravitational wave detection experiments and express our results as semi-analytic relations of the form G{mu}({Omega}{sub gw} h {sup 2})/c {sup 2}, to allow for direct computation of the tension constraints for future experiments. These results can be applied to new constraints on {Omega}{sub gw} h {sup 2} as they are imposed. Experiments operating in different frequency bands probe different parts of the gravitational wave spectrum of a cosmic string network and are sensitive to different uncertainties in the underlying cosmic string model parameters. We compute the gravitational wave spectra of cosmic string networks based on the one-scale model, covering all the parameter space accessed by each experiment that is strongly dependent on the birth scale of loops relative to the horizon, {alpha}. The upper limits on the string tension avoid any assumptions on the model parameters. We perform this investigation for Pulsar Timing Array experiments of different durations, as well as ground-based and space-borne interferometric detectors.

  20. Direct/indirect detection signatures of nonthermally produced dark matter

    SciTech Connect

    Nagai, Minoru; Nakayama, Kazunori

    2008-09-15

    We study direct and indirect detection possibilities of neutralino dark matter produced nonthermally by, e.g., the decay of long-lived particles, as is easily implemented in the case of anomaly or mirage-mediation models. In this scenario, large self-annihilation cross sections are required to account for the present dark matter abundance, and it leads to significant enhancement of the gamma-ray signature from the galactic center and the positron flux from the dark matter annihilation. It is found that GLAST and PAMELA will find the signal or give tight constraints on such nonthermal production scenarios of neutralino dark matter.

  1. Disentangling Dark Matter Dynamics with Directional Detection

    SciTech Connect

    Lisanti, Mariangela; Wacker, Jay G.; /SLAC

    2009-12-16

    Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a non-minimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.

  2. Disentangling dark matter dynamics with directional detection

    SciTech Connect

    Lisanti, Mariangela; Wacker, Jay G.

    2010-05-01

    Inelastic dark matter reconciles the DAMA anomaly with other null direct detection experiments and points to a nonminimal structure in the dark matter sector. In addition to the dominant inelastic interaction, dark matter scattering may have a subdominant elastic component. If these elastic interactions are suppressed at low momentum transfer, they will have similar nuclear recoil spectra to inelastic scattering events. While upcoming direct detection experiments will see strong signals from such models, they may not be able to unambiguously determine the presence of the subdominant elastic scattering from the recoil spectra alone. We show that directional detection experiments can separate elastic and inelastic scattering events and discover the underlying dynamics of dark matter models.

  3. Microgels for multiplex and direct fluorescence detection

    NASA Astrophysics Data System (ADS)

    Causa, Filippo; Aliberti, Anna; Cusano, Angela M.; Battista, Edmondo; Netti, Paolo A.

    2015-05-01

    Blood borne oligonucleotides fragments contain useful clinical information whose detection and monitoring represent the new frontier in liquid biopsy as they can transform the current diagnosis procedure. For instance, recent studies have identified a new class of circulating biomarkers such as s miRNAs, and demonstrated that changes in their concentration are closely associated with the development of cancer and other pathologies. However, direct detection of miRNAs in body fluids is particularly challenging and demands high sensitivity -concentration range between atto to femtomolarspecificity, and multiplexing Here we report on engineered multifunctional microgels and innovative probe design for a direct and multiplex detection of relevant clinical miRNAs in fluorescence by single particle assay. Polyethyleneglycol-based microgels have a coreshell architecture with two spectrally encoded fluorescent dyes for multiplex analyses and are endowed with fluorescent probes for miRNA detection. Encoding and detection fluorescence signals are distinguishable by not overlapping emission spectra. Tuneable fluorescence probe conjugation and corresponding emission confinement on single microgel allows for enhanced target detection. Such suspension array has indeed high selectivity and sensitivity with a detection limit of 10-15 M and a dynamic range from 10-9 to 10-15 M. We believe that sensitivity in the fM concentration range, signal background minimization, multiplexed capability and direct measurement of such microgels will translate into diagnostic benefits opening up new roots toward liquid biopsy in the context of point-of-care testing through an easy and fast detection of sensitive diagnostic biomarkers directly in serum.

  4. Physics from solar neutrinos in dark matter direct detection experiments

    NASA Astrophysics Data System (ADS)

    Cerdeño, David G.; Fairbairn, Malcolm; Jubb, Thomas; Machado, Pedro A. N.; Vincent, Aaron C.; Bœhm, Céline

    2016-05-01

    The next generation of dark matter direct detection experiments will be sensitive to both coherent neutrino-nucleus and neutrino-electron scattering. This will enable them to explore aspects of solar physics, perform the lowest energy measurement of the weak angle sin2 θ W to date, and probe contributions from new theories with light mediators. In this article, we compute the projected nuclear and electron recoil rates expected in several dark matter direct detection experiments due to solar neutrinos, and use these estimates to quantify errors on future measurements of the neutrino fluxes, weak mixing angle and solar observables, as well as to constrain new physics in the neutrino sector. Our analysis shows that the combined rates of solar neutrino events in second generation experiments (SuperCDMS and LZ) can yield a measurement of the pp flux to 2.5% accuracy via electron recoil, and slightly improve the 8B flux determination. Assuming a low-mass argon phase, projected tonne-scale experiments like DARWIN can reduce the uncertainty on both the pp and boron-8 neutrino fluxes to below 1%. Finally, we use current results from LUX, SuperCDMS and CDMSlite to set bounds on new interactions between neutrinos and electrons or nuclei, and show that future direct detection experiments can be used to set complementary constraints on the parameter space associated with light mediators.

  5. Wind measurement via direct detection lidar

    NASA Astrophysics Data System (ADS)

    Afek, I.; Sela, N.; Narkiss, N.; Shamai, G.; Tsadka, S.

    2013-10-01

    Wind sensing Lidar is considered a promising technology for high quality wind measurements required for various applications such as hub height wind resource assessment, power curve measurements and advanced, real time, forward looking turbine control. Until recently, the only available Lidar technology was based on coherent Doppler shift detection, whose market acceptance has been slow primarily due to its exuberant price. Direct detection Lidar technology provides an alternative to remote sensing of wind by incorporating high precision measurement, a robust design and an affordable price tag.

  6. DIRECTIONAL DETECTION OF FISSION-SPECTRUM NEUTRONS.

    SciTech Connect

    VANIER,P.E.

    2007-05-04

    Conventional neutron detectors consisting of {sup 3}He tubes surrounded by a plastic moderator can be quite efficient in detecting fission spectrum neutrons, but do not indicate the direction of the incident radiation. We have developed a new directional detector based on double proton recoil in two separated planes of plastic scintillators. This method allows the spectrum of the neutrons to be measured by a combination of peak amplitude in the first plane and time of flight to the second plane. It also allows the determination of the angle of scattering in the first plane. If the planes are position-sensitive detectors, then the direction of the scattered neutron is known, and the direction of the incident neutron can be determined to lie on a cone of s fixed angle. The superposition of many such cones generates an image that indicates the presence of a localized source. Typical background neutron fluences from the interaction of cosmic rays with the atmosphere are low and fairly uniformly distributed in angle. Directional detection helps to locate a manmade source in the presence of natural background. Monte Carlo simulations are compared with experimental results.

  7. Aberration features in directional dark matter detection

    SciTech Connect

    Bozorgnia, Nassim; Gelmini, Graciela B.; Gondolo, Paolo E-mail: gelmini@physics.ucla.edu

    2012-08-01

    The motion of the Earth around the Sun causes an annual change in the magnitude and direction of the arrival velocity of dark matter particles on Earth, in a way analogous to aberration of stellar light. In directional detectors, aberration of weakly interacting massive particles (WIMPs) modulates the pattern of nuclear recoil directions in a way that depends on the orbital velocity of the Earth and the local galactic distribution of WIMP velocities. Knowing the former, WIMP aberration can give information on the latter, besides being a curious way of confirming the revolution of the Earth and the extraterrestrial provenance of WIMPs. While observing the full aberration pattern requires extremely large exposures, we claim that the annual variation of the mean recoil direction or of the event counts over specific solid angles may be detectable with moderately large exposures. For example, integrated counts over Galactic hemispheres separated by planes perpendicular to Earth's orbit would modulate annually, resulting in Galactic Hemisphere Annual Modulations (GHAM) with amplitudes larger than the usual non-directional annual modulation.

  8. Direct detection of dark matter axions with directional sensitivity

    SciTech Connect

    Irastorza, Igor G.; García, Juan A. E-mail: jagarpas@unizar.es

    2012-10-01

    We study the directional effect of the expected axion dark matter signal in a resonant cavity of an axion haloscope detector, for cavity geometries not satisfying the condition that the axion de Broglie wavelength λ{sub a} is sufficiently larger than the cavity dimensions L for a fully coherent conversion, i.e. λ{sub a}∼>2πL. We focus on long thin cavities immersed in dipole magnets and find, for appropriately chosen cavity lengths, an O(1) modulation of the signal with the cavity orientation with respect the momentum distribution of the relic axion background predicted by the isothermal sphere model for the galactic dark matter halo. This effect can be exploited to design directional axion dark matter detectors, providing an unmistakable signature of the extraterrestrial origin of a possible positive detection. Moreover, the precise shape of the modulation may give information of the galactic halo distribution and, for specific halo models, give extra sensitivity for higher axion masses.

  9. Direct and indirect constraints on CP-violating Higgs-quark and Higgs-gluon interactions

    NASA Astrophysics Data System (ADS)

    Chien, Y. T.; Cirigliano, V.; Dekens, W.; de Vries, J.; Mereghetti, E.

    2016-02-01

    We investigate direct and indirect constraints on the complete set of anomalous CP-violating Higgs couplings to quarks and gluons originating from dimension-6 operators, by studying their signatures at the LHC and in electric dipole moments (EDMs). We show that existing uncertainties in hadronic and nuclear matrix elements have a significant impact on the interpretation of EDM experiments, and we quantify the improvements needed to fully exploit the power of EDM searches. Currently, the best bounds on the anomalous CP-violating Higgs interactions come from a combination of EDM measurements and the data from LHC Run 1. We argue that Higgs production cross section and branching ratios measurements at the LHC Run 2 will not improve the constraints significantly. On the other hand, the bounds on the couplings scale roughly linearly with EDM limits, so that future theoretical and experimental EDM developments can have a major impact in pinning down interactions of the Higgs.

  10. Feature, design intention and constraint preservation for direct modeling of 3D freeform surfaces

    NASA Astrophysics Data System (ADS)

    Fu, Luoting; Kara, Levent Burak; Shimada, Kenji

    2012-06-01

    Direct modeling has recently emerged as a suitable approach for 3D free-form shape modeling in industrial design. It has several advantages over the conventional, parametric modeling techniques, including natural user interactions, as well as the underlying, automatic feature-preserving shape deformation algorithms. However, current direct modeling packages still lack several capabilities critical for product design, such as managing aesthetic design intentions, and enforcing dimensional, geometric constraints. In this paper, we describe a novel 3D surface editing system capable of jointly accommodating aesthetic design intentions expressed in the form of surface painting and color-coded annotations, as well as engineering constraints expressed as dimensions. The proposed system is built upon differential coordinates and constrained least squares, and is intended for conceptual design that involves frequent shape tuning and explorations. We also provide an extensive review of the state-of-the-art direct modeling approaches for 3D mesh-based, freeform surfaces, with an emphasis on the two broad categories of shape deformation algorithms developed in the relevant field of geometric modeling. [Figure not available: see fulltext.

  11. Neutralino Dark Matter: Update on Direct and Indirect Detection

    SciTech Connect

    Scopel, S.

    2005-12-02

    Neutralinos represent a viable solution to the Dark Matter problem. In particular, while I discuss here a wide range for their masses, I will deserve a special attention to light neutralinos, which arise in supersymmetric models without unifications conditions of gaugino masses at the GUT scale. They have sizeable direct and indirect detection signals, which are bounded from below by the cosmological constraint on their relic abundance, but are not yet excluded by present direct and indirect searches, including limits coming from the BR(Bs {yields} {mu}+ + {mu}-) decay rate. They represent so an interesting experimental challenge. An intriguing aspect of light neutralinos is also that they could explain the DAMA modulation effect in a still existing compatibility window with other direct search experiments. I also discuss the gamma-ray signal from dark matter annihilation in our Galaxy and give some examples of external objects, namely the Andromeda Galaxy (M31) and M87. Predictions for the fluxes turn out to be below the level required to explain the possible indications of a {gamma}-ray excess shown by EGRET, CANGAROO-II and HESS (toward the Galactic Center) and HEGRA (from M87). As far as future experiments are concerned, only the signal from the galactic center could be accessible to both satellite-borne experiments and to ACTs, even though this requires very steep dark matter density profiles.

  12. A Theory and Model of Conflict Detection in Air Traffic Control: Incorporating Environmental Constraints

    ERIC Educational Resources Information Center

    Loft, Shayne; Bolland, Scott; Humphreys, Michael S.; Neal, Andrew

    2009-01-01

    A performance theory for conflict detection in air traffic control is presented that specifies how controllers adapt decisions to compensate for environmental constraints. This theory is then used as a framework for a model that can fit controller intervention decisions. The performance theory proposes that controllers apply safety margins to…

  13. The Earth's velocity for direct detection experiments

    NASA Astrophysics Data System (ADS)

    McCabe, Christopher

    2014-02-01

    The Earth's velocity relative to the Sun in galactic coordinates is required in the rate calculation for direct detection experiments. We provide a rigorous derivation of this quantity to first order in the eccentricity of the Earth's orbit. We also discuss the effect of the precession of the equinoxes, which has hitherto received little explicit discussion. Comparing with other expressions in the literature, we confirm that the expression of Lee, Lisanti and Safdi is correct, while the expression of Lewin and Smith, the de facto standard expression, contains an error. For calculations of the absolute event rate, the leading order expression is sufficient while for modulation searches, an expression with the eccentricity is required for accurate predictions of the modulation phase.

  14. The Direct Detectability of Giant Exoplanets in the Optical

    NASA Astrophysics Data System (ADS)

    Greco, Johnny P.; Burrows, Adam

    2015-08-01

    Motivated by the possibility that a coronagraph will be put on the Wide-field Infrared Survey Telescope (WFIRST)/Astrophysics Focused Telescope Assets (AFTA), we explore the direct detectability of extrasolar giant planets (EGPs) in the optical. We quantify a planet's detectability by the fraction of its orbit for which it is in an observable configuration ({f}{obs}). Using a suite of Monte Carlo experiments, we study the dependence of {f}{obs} upon the inner working angle (IWA) and minimum achievable contrast ({C}{min}) of the direct-imaging observatory; the planet's phase function, geometric albedo, single-scattering albedo, radius, and distance from Earth; and the semimajor axis distribution of EGPs. We calculate phase functions for a given geometric or single-scattering albedo, assuming various scattering mechanisms. We find that the Lambertian phase function can predict significantly larger {f}{obs}s with respect to the more realistic Rayleigh phase function. For observations made with WFIRST/AFTA's baseline capabilities ({C}{min}∼ {10}-9, {IWA}∼ 0\\buildrel{\\prime\\prime}\\over{.} 2), Jupiter-like planets orbiting stars within 10, 30, and 50 pc of Earth have volume-averaged observability fractions of ∼12%, 3%, and 0.5%, respectively. At 10 pc, such observations yield {f}{obs}\\gt 1% for low- to modest-eccentricity planets with semimajor axes in the range ∼2–10 AU. If {C}{min}={10}-10, this range extends to ∼35 AU. We find that, in all but the most optimistic configurations, the probability for detection in a blind search is low (< 5%). However, with orbital parameter constraints from long-term radial-velocity campaigns and Gaia astrometry, the tools we develop in this work can be used to determine both the most promising systems to target and when to observe them.

  15. Direct Detection of Soil-Bound Prions

    PubMed Central

    Genovesi, Sacha; Leita, Liviana; Sequi, Paolo; Andrighetto, Igino; Sorgato, M. Catia; Bertoli, Alessandro

    2007-01-01

    Scrapie and chronic wasting disease are contagious prion diseases affecting sheep and cervids, respectively. Studies have indicated that horizontal transmission is important in sustaining these epidemics, and that environmental contamination plays an important role in this. In the perspective of detecting prions in soil samples from the field by more direct methods than animal-based bioassays, we have developed a novel immuno-based approach that visualises in situ the major component (PrPSc) of prions sorbed onto agricultural soil particles. Importantly, the protocol needs no extraction of the protein from soil. Using a cell-based assay of infectivity, we also report that samples of agricultural soil, or quartz sand, acquire prion infectivity after exposure to whole brain homogenates from prion-infected mice. Our data provide further support to the notion that prion-exposed soils retain infectivity, as recently determined in Syrian hamsters intracerebrally or orally challanged with contaminated soils. The cell approach of the potential infectivity of contaminated soil is faster and cheaper than classical animal-based bioassays. Although it suffers from limitations, e.g. it can currently test only a few mouse prion strains, the cell model can nevertheless be applied in its present form to understand how soil composition influences infectivity, and to test prion-inactivating procedures. PMID:17957252

  16. Neutralino dark matter in minimal supergravity: Direct detection versus collider searches

    SciTech Connect

    Baer, H.; Brhlik, M.

    1998-01-01

    We calculate expected event rates for direct detection of relic neutralinos as a function of parameter space of the minimal supergravity model. Numerical results are presented for the specific case of a {sup 73}Ge detector. We find significant detection rates (R{gt}0.01events/kg/day) in regions of parameter space most favored by constraints from B{r_arrow}X{sub s}{gamma} and the cosmological relic density of neutralinos. The detection rates are especially large in regions of large tan{beta}, where many conventional signals for supersymmetry at collider experiments are difficult to detect. If the parameter tan{beta} is large, then there is a significant probability that the first direct evidence for supersymmetry could come from direct detection experiments, rather than from collider searches for sparticles. {copyright} {ital 1997} {ital The American Physical Society}

  17. Solution algorithm of a quasi-Lambert's problem with fixed flight-direction angle constraint

    NASA Astrophysics Data System (ADS)

    Luo, Qinqin; Meng, Zhanfeng; Han, Chao

    2011-04-01

    A two-point boundary value problem of the Kepler orbit similar to Lambert's problem is proposed. The problem is to find a Kepler orbit that will travel through the initial and final points in a specified flight time given the radial distances of the two points and the flight-direction angle at the initial point. The Kepler orbits that meet the geometric constraints are parameterized via the universal variable z introduced by Bate. The formula for flight time of the orbits is derived. The admissible interval of the universal variable and the variation pattern of the flight time are explored intensively. A numerical iteration algorithm based on the analytical results is presented to solve the problem. A large number of randomly generated examples are used to test the reliability and efficiency of the algorithm.

  18. Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints

    PubMed Central

    Zhang, Heng; Liu, Yanli; Tan, Jindong

    2015-01-01

    A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH) technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset. PMID:26102492

  19. Loop Closing Detection in RGB-D SLAM Combining Appearance and Geometric Constraints.

    PubMed

    Zhang, Heng; Liu, Yanli; Tan, Jindong

    2015-01-01

    A kind of multi feature points matching algorithm fusing local geometric constraints is proposed for the purpose of quickly loop closing detection in RGB-D Simultaneous Localization and Mapping (SLAM). The visual feature is encoded with BRAND (binary robust appearance and normals descriptor), which efficiently combines appearance and geometric shape information from RGB-D images. Furthermore, the feature descriptors are stored using the Locality-Sensitive-Hashing (LSH) technique and hierarchical clustering trees are used to search for these binary features. Finally, the algorithm for matching of multi feature points using local geometric constraints is provided, which can effectively reject the possible false closure hypotheses. We demonstrate the efficiency of our algorithms by real-time RGB-D SLAM with loop closing detection in indoor image sequences taken with a handheld Kinect camera and comparative experiments using other algorithms in RTAB-Map dealing with a benchmark dataset. PMID:26102492

  20. Deciphering inflation with gravitational waves: Cosmic microwave background polarization vs direct detection with laser interferometers

    SciTech Connect

    Smith, Tristan L.; Peiris, Hiranya V.; Cooray, Asantha

    2006-06-15

    A detection of the primordial gravitational wave background is considered to be the 'smoking-gun' evidence for inflation. While superhorizon waves are probed with cosmic microwave background (CMB) polarization, the relic background will be studied with laser interferometers. The long lever arm spanned by the two techniques improves constraints on the inflationary potential and validation of consistency relations expected under inflation. If gravitational waves with a tensor-to-scalar amplitude ratio greater than 0.01 are detected by the CMB, then a direct-detection experiment with a sensitivity consistent with current concept studies should be pursued vigorously. If no primordial tensors are detected by the CMB, a direct-detection experiment to understand the simplest form of inflation must have a sensitivity improved by two to 3 orders of magnitude over current plans.

  1. Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

    NASA Astrophysics Data System (ADS)

    Appelquist, T.; Berkowitz, E.; Brower, R. C.; Buchoff, M. I.; Fleming, G. T.; Jin, X.-Y.; Kiskis, J.; Kribs, G. D.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Rinaldi, E.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Vranas, P.; Weinberg, E.; Witzel, O.; Lattice Strong Dynamics LSD Collaboration

    2015-10-01

    We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory—"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N ) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1 /mB6 , suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

  2. Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

    DOE PAGESBeta

    Appelquist, T.; Berkowitz, E.; Brower, R. C.; Buchoff, M. I.; Fleming, G. T.; Jin, X. Y.; Kiskis, J.; Kribs, G. D.; Neil, E. T.; Osborn, J. C.; et al

    2015-10-23

    We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar “stealth baryon” dark matter candidate, arising from a dark SU(4) confining gauge theory—“stealth dark matter.” In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest “baryon” states in SU(3) and SU(4) gauge theories using themore » background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be possibly detectable in the dark matter mass range of about 200–700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m6B, suggests the observable dark matter mass range is not appreciably modified. We highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.« less

  3. Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

    PubMed

    Appelquist, T; Berkowitz, E; Brower, R C; Buchoff, M I; Fleming, G T; Jin, X-Y; Kiskis, J; Kribs, G D; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Syritsyn, S; Vranas, P; Weinberg, E; Witzel, O

    2015-10-23

    We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

  4. Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability.

    PubMed

    Appelquist, T; Berkowitz, E; Brower, R C; Buchoff, M I; Fleming, G T; Jin, X-Y; Kiskis, J; Kribs, G D; Neil, E T; Osborn, J C; Rebbi, C; Rinaldi, E; Schaich, D; Schroeder, C; Syritsyn, S; Vranas, P; Weinberg, E; Witzel, O

    2015-10-23

    We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar "stealth baryon" dark matter candidate, arising from a dark SU(4) confining gauge theory-"stealth dark matter." In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest "baryon" states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be potentially detectable in the dark matter mass range of about 200-700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m(B)(6), suggests the observable dark matter mass range is not appreciably modified. We briefly highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter. PMID:26551103

  5. Detecting Stealth Dark Matter Directly through Electromagnetic Polarizability

    SciTech Connect

    Appelquist, T.; Berkowitz, E.; Brower, R. C.; Buchoff, M. I.; Fleming, G. T.; Jin, X. Y.; Kiskis, J.; Kribs, G. D.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Rinaldi, E.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Vranas, P.; Weinberg, E.; Witzel, O.

    2015-10-23

    We calculate the spin-independent scattering cross section for direct detection that results from the electromagnetic polarizability of a composite scalar “stealth baryon” dark matter candidate, arising from a dark SU(4) confining gauge theory—“stealth dark matter.” In the nonrelativistic limit, electromagnetic polarizability proceeds through a dimension-7 interaction leading to a very small scattering cross section for dark matter with weak-scale masses. This represents a lower bound on the scattering cross section for composite dark matter theories with electromagnetically charged constituents. We carry out lattice calculations of the polarizability for the lightest “baryon” states in SU(3) and SU(4) gauge theories using the background field method on quenched configurations. We find the polarizabilities of SU(3) and SU(4) to be comparable (within about 50%) normalized to the stealth baryon mass, which is suggestive for extensions to larger SU(N) groups. The resulting scattering cross sections with a xenon target are shown to be possibly detectable in the dark matter mass range of about 200–700 GeV, where the lower bound is from the existing LUX constraint while the upper bound is the coherent neutrino background. Significant uncertainties in the cross section remain due to the more complicated interaction of the polarizablity operator with nuclear structure; however, the steep dependence on the dark matter mass, 1/m6B, suggests the observable dark matter mass range is not appreciably modified. We highlight collider searches for the mesons in the theory as well as the indirect astrophysical effects that may also provide excellent probes of stealth dark matter.

  6. Model-independent indirect detection constraints on hidden sector dark matter

    NASA Astrophysics Data System (ADS)

    Elor, Gilly; Rodd, Nicholas L.; Slatyer, Tracy R.; Xue, Wei

    2016-06-01

    If dark matter inhabits an expanded ``hidden sector'', annihilations may proceed through sequential decays or multi-body final states. We map out the potential signals and current constraints on such a framework in indirect searches, using a model-independent setup based on multi-step hierarchical cascade decays. While remaining agnostic to the details of the hidden sector model, our framework captures the generic broadening of the spectrum of secondary particles (photons, neutrinos, e+e‑ and bar p p) relative to the case of direct annihilation to Standard Model particles. We explore how indirect constraints on dark matter annihilation limit the parameter space for such cascade/multi-particle decays. We investigate limits from the cosmic microwave background by Planck, the Fermi measurement of photons from the dwarf galaxies, and positron data from AMS-02. The presence of a hidden sector can change the constraints on the dark matter by up to an order of magnitude in either direction (although the effect can be much smaller). We find that generally the bound from the Fermi dwarfs is most constraining for annihilations to photon-rich final states, while AMS-02 is most constraining for electron and muon final states; however in certain instances the CMB bounds overtake both, due to their approximate independence on the details of the hidden sector cascade. We provide the full set of cascade spectra considered here as publicly available code with examples at http://web.mit.edu/lns/research/CascadeSpectra.html.

  7. Model-independent indirect detection constraints on hidden sector dark matter

    NASA Astrophysics Data System (ADS)

    Elor, Gilly; Rodd, Nicholas L.; Slatyer, Tracy R.; Xue, Wei

    2016-06-01

    If dark matter inhabits an expanded ``hidden sector'', annihilations may proceed through sequential decays or multi-body final states. We map out the potential signals and current constraints on such a framework in indirect searches, using a model-independent setup based on multi-step hierarchical cascade decays. While remaining agnostic to the details of the hidden sector model, our framework captures the generic broadening of the spectrum of secondary particles (photons, neutrinos, e+e- and bar p p) relative to the case of direct annihilation to Standard Model particles. We explore how indirect constraints on dark matter annihilation limit the parameter space for such cascade/multi-particle decays. We investigate limits from the cosmic microwave background by Planck, the Fermi measurement of photons from the dwarf galaxies, and positron data from AMS-02. The presence of a hidden sector can change the constraints on the dark matter by up to an order of magnitude in either direction (although the effect can be much smaller). We find that generally the bound from the Fermi dwarfs is most constraining for annihilations to photon-rich final states, while AMS-02 is most constraining for electron and muon final states; however in certain instances the CMB bounds overtake both, due to their approximate independence on the details of the hidden sector cascade. We provide the full set of cascade spectra considered here as publicly available code with examples at http://web.mit.edu/lns/research/CascadeSpectra.html.

  8. Indirect detection constraints on the model space of dark matter effective theories

    NASA Astrophysics Data System (ADS)

    Carpenter, Linda M.; Colburn, Russell; Goodman, Jessica

    2015-11-01

    Using limits on photon flux from dwarf spheroidal galaxies, we place bounds on the parameter space of models in which dark matter annihilates into multiple final state particle pair channels. We derive constraints on effective operator models with dark matter couplings to third generation fermions and to pairs of standard model vector bosons. We present limits in various slices of model parameter space along with estimations of the region of maximal validity of the effective operator approach for indirect detection. We visualize our bounds for models with multiple final state annihilations by projecting parameter space constraints onto triangles, a technique familiar from collider physics; and we compare our bounds to collider limits on equivalent models.

  9. Systematic aspects of direct extrasolar planet detection

    NASA Technical Reports Server (NTRS)

    Brown, Robert A.

    1988-01-01

    Using the first optical observatory in space, the Hubble Space Telescope, images of possible extrasolar planets will have poor contrast against the background of diffracted and scattered starlight. The very long exposure time required to achieve an adequate signal-to-noise ratio will make their detection infeasible. For a future telescope, a 16-fold increase in either the smoothness of the collecting area of the optics would reduce the exposure time to a tolerable value, but the contrast would remain low and the required photometric precision high. In this situation, the feasibility of detection would be contingent on the careful identification and control of systematic errors.

  10. Polymeric assay film for direct colorimetric detection

    DOEpatents

    Charych, Deborah; Nagy, Jon; Spevak, Wayne

    2002-01-01

    A lipid bilayer with affinity to an analyte, which directly signals binding by a changes in the light absorption spectra. This novel assay means and method has special applications in the drug development and medical testing fields. Using a spectrometer, the system is easily automated, and a multiple well embodiment allows inexpensive screening and sequential testing. This invention also has applications in industry for feedstock and effluent monitoring.

  11. Polymeric assay film for direct colorimetric detection

    DOEpatents

    Charych, Deborah; Nagy, Jon; Spevak, Wayne

    1999-01-01

    A lipid bilayer with affinity to an analyte, which directly signals binding by a changes in the light absorption spectra. This novel assay means and method has special applications in the drug development and medical testing fields. Using a spectrometer, the system is easily automated, and a multiple well embodiment allows inexpensive screening and sequential testing. This invention also has applications in industry for feedstock and effluent monitoring.

  12. Indirect detection of radiation sources through direct detection of radiolysis products

    DOEpatents

    Farmer, Joseph C.; Fischer, Larry E.; Felter, Thomas E.

    2010-04-20

    A system for indirectly detecting a radiation source by directly detecting radiolytic products. The radiation source emits radiation and the radiation produces the radiolytic products. A fluid is positioned to receive the radiation from the radiation source. When the fluid is irradiated, radiolytic products are produced. By directly detecting the radiolytic products, the radiation source is detected.

  13. Pulmonary nodule detection in CT images based on shape constraint CV model

    SciTech Connect

    Wang, Bing; Tian, Xuedong; Wang, Qian; Yang, Ying; Xie, Hongzhi E-mail: xiehongzhi@medmail.com.cn; Zhang, Shuyang; Gu, Lixu E-mail: xiehongzhi@medmail.com.cn

    2015-03-15

    Purpose: Accurate detection of pulmonary nodules remains a technical challenge in computer-aided diagnosis systems because some nodules may adhere to the blood vessels or the lung wall, which have low contrast compared to the surrounding tissues. In this paper, the analysis of typical shape features of candidate nodules based on a shape constraint Chan–Vese (CV) model combined with calculation of the number of blood branches adhered to nodule candidates is proposed to reduce false positive (FP) nodules from candidate nodules. Methods: The proposed scheme consists of three major stages: (1) Segmentation of lung parenchyma from computed tomography images. (2) Extraction of candidate nodules. (3) Reduction of FP nodules. A gray level enhancement combined with a spherical shape enhancement filter is introduced to extract the candidate nodules and their sphere-like contour regions. FPs are removed by analysis of the typical shape features of nodule candidates based on the CV model using spherical constraint and by investigating the number of blood branches adhered to the candidate nodules. The constrained shapes of CV model are automatically achieved from the extracted candidate nodules. Results: The detection performance was evaluated on 127 nodules of 103 cases including three types of challenging nodules, which are juxta-pleural nodules, juxta-vascular nodules, and ground glass opacity nodules. The free-receiver operating characteristic (FROC) curve shows that the proposed method is able to detect 88% of all the nodules in the data set with 4 FPs per case. Conclusions: Evaluation shows that the authors’ method is feasible and effective for detection of three types of nodules in this study.

  14. Reproductive constraints, direct fitness and indirect fitness benefits explain helping behaviour in the primitively eusocial wasp, Polistes canadensis.

    PubMed

    Sumner, Seirian; Kelstrup, Hans; Fanelli, Daniele

    2010-06-01

    A key step in the evolution of sociality is the abandonment of independent breeding in favour of helping. In cooperatively breeding vertebrates and primitively eusocial insects, helpers are capable of leaving the group and reproducing independently, and yet many do not. A fundamental question therefore is why do helpers help? Helping behaviour may be explained by constraints on independent reproduction and/or benefits to individuals from helping. Here, we examine simultaneously the reproductive constraints and fitness benefits underlying helping behaviour in a primitively eusocial paper wasp. We gave 31 helpers the opportunity to become egg-layers on their natal nests by removing nestmates. This allowed us to determine whether helpers are reproductively constrained in any way. We found that age strongly influenced whether an ex-helper could become an egg-layer, such that young ex-helpers could become egg-layers while old ex-helpers were less able. These differential reproductive constraints enabled us to make predictions about the behaviours of ex-helpers, depending on the relative importance of direct and indirect fitness benefits. We found little evidence that indirect fitness benefits explain helping behaviour, as 71 per cent of ex-helpers left their nests before the end of the experiment. In the absence of reproductive constraints, however, young helpers value direct fitness opportunities over indirect fitness. We conclude that a combination of reproductive constraints and potential for future direct reproduction explain helping behaviour in this species. Testing several competing explanations for helping behaviour simultaneously promises to advance our understanding of social behaviour in animal groups.

  15. Size as a line of least resistance II: direct selection on size or correlated response due to constraints?

    PubMed

    Marroig, Gabriel; Cheverud, James

    2010-05-01

    Evolutionary change in New World Monkey (NWM) skulls occurred primarily along the line of least resistance defined by size (including allometric) variation (g(max)). Although the direction of evolution was aligned with this axis, it was not clear whether this macroevolutionary pattern results from the conservation of within population genetic covariance patterns (long-term constraint) or long-term selection along a size dimension, or whether both, constraints and selection, were inextricably involved. Furthermore, G-matrix stability can also be a consequence of selection, which implies that both, constraints embodied in g(max) and evolutionary changes observed on the trait averages, would be influenced by selection. Here, we describe a combination of approaches that allows one to test whether any particular instance of size evolution is a correlated by-product due to constraints (g(max)) or is due to direct selection on size and apply it to NWM lineages as a case study. The approach is based on comparing the direction and amount of evolutionary change produced by two different simulated sets of net-selection gradients (beta), a size (isometric and allometric size) and a nonsize set. Using this approach it is possible to distinguish between the two hypotheses (indirect size evolution due to constraints or direct selection on size), because although both may produce an evolutionary response aligned with g(max), the amount of change produced by random selection operating through the variance/covariance patterns (constraints hypothesis) will be much smaller than that produced by selection on size (selection hypothesis). Furthermore, the alignment of simulated evolutionary changes with g(max) when selection is not on size is not as tight as when selection is actually on size, allowing a statistical test of whether a particular observed case of evolution along the line of least resistance is the result of selection along it or not. Also, with matrix diagonalization

  16. Automatic polyp detection using global geometric constraints and local intensity variation patterns.

    PubMed

    Tajbakhsh, Nima; Gurudu, Suryakanth R; Liang, Jianming

    2014-01-01

    This paper presents a new method for detecting polyps in colonoscopy. Its novelty lies in integrating the global geometric constraints of polyps with the local patterns of intensity variation across polyp boundaries: the former drives the detector towards the objects with curvy boundaries, while the latter minimizes the misleading effects of polyp-like structures. This paper makes three original contributions: (1) a fast and discriminative patch descriptor for precisely characterizing patterns of intensity variation across boundaries, (2) a new 2-stage classification scheme for accurately excluding non-polyp edges from an overcomplete edge map, and (3) a novel voting scheme for robustly localizing polyps from the retained edges. Evaluations on a public database and our own videos demonstrate that our method is promising and outperforms the state-of-the-art methods. PMID:25485377

  17. Directional complex-valued coherence attributes for discontinuous edge detection

    NASA Astrophysics Data System (ADS)

    Wang, Shangxu; Yuan, Sanyi; Yan, Binpeng; He, Yanxiao; Sun, Wenju

    2016-06-01

    We propose directional complex-valued coherence attributes through a simple calculation of the cross-correlation between neighboring complex seismic traces normalized by their corresponding envelope within a local time window along a certain spatial direction. For 3D seismic data with varying directional geological edges, the complex-valued coherence attributes along different spatial directions are distinct, and the coherence along a certain direction can highlight discontinuities at (or near) the perpendicular direction. These separate directional coherence attributes can assist in interpreting the dominant direction(s) of fault development, which is vital in determining sweet spots and locating hydrocarbon wells, and can facilitate the detection of weak or hidden geological edges. In addition, we obtain the minimum complex-valued coherence attribute by comparing all directional coherence volumes to describe the entire lineament and spatial extension direction of geological abnormalities (e.g., channels). In essence, the minimum coherence attribute can be regarded as the result of implementing multi-trace complex-valued coherence calculation along the direction perpendicular to the structural trend. An example of 3D synthetic data with a fault system and channel complex is employed to demonstrate the effectiveness of the directional and minimum complex-valued coherence attributes. The application on a real 3D seismic data of tight sandstone reservoir with faults, flexures and fractures, illustrates that the directional and minimum complex-valued coherence attributes can highlight subtle structures and the directional details of geological abnormalities, which are favorably consistent with the manually interpreted results.

  18. Predictions of hydrodynamic simulations for direct dark matter detection

    NASA Astrophysics Data System (ADS)

    Bozorgnia, Nassim; Calore, Francesca; Schaller, Matthieu; Lovell, Mark; Bertone, Gianfranco; Frenk, Carlos S.; Crain, Robert A.; Navarro, Julio F.; Schaye, Joop; Theuns, Tom

    2016-05-01

    We study the effects of galaxy formation on dark matter direct detection using hydrodynamic simulations obtained from the “Evolution and Assembly of GaLaxies and their Environments” (EAGLE) and APOSTLE projects. We extract the local dark matter density and velocity distribution of the simulated Milky Way analogues, and use them directly to perform an analysis of current direct detection data. The local dark matter density of the Milky Way-like galaxies is 0.41–0.73 GeV/cm3, and a Maxwellian distribution (with best fit peak speed of 223–289 km/s) describes well the local dark matter speed distribution. We find that the consistency between the result of different direct detection experiments cannot be improved by using the dark matter distribution of the simulated haloes.

  19. Comparing readout strategies to directly detect dark matter

    NASA Astrophysics Data System (ADS)

    Billard, J.

    2015-01-01

    Over the past decades, several ideas and technologies have been developed to directly detect weakly interacting massive particles (WIMP) from the galactic halo. All these detection strategies share the common goal of discriminating a WIMP signal from the residual backgrounds. By directly detecting WIMPs, one can measure some or all of the observables associated to each nuclear recoil candidates, such as their energy and direction. In this study, we compare and examine the discovery potentials of each readout strategies from counting only (bubble chambers) to directional detectors (Time Projection Chambers) with 1d-, 2d-, and 3d-sensitivity. Using a profile likelihood analysis, we show that, in the case of a large and irreducible background contamination characterized by an energy distribution similar to the expected WIMP signal, directional information can improve the sensitivity of the experiment by several orders of magnitude. We also found that 1d directional detection is only less effective than a full 3d directional sensitivity by about a factor of 3, or 10 if we assume no sense recognition, still improving by a factor of 2 or more if only the energy of the events is being measured.

  20. Nuclear Magnetic Resonance-Assisted Prediction of Secondary Structure for RNA: Incorporation of Direction-Dependent Chemical Shift Constraints.

    PubMed

    Chen, Jonathan L; Bellaousov, Stanislav; Tubbs, Jason D; Kennedy, Scott D; Lopez, Michael J; Mathews, David H; Turner, Douglas H

    2015-11-17

    Knowledge of RNA structure is necessary to determine structure-function relationships and to facilitate design of potential therapeutics. RNA secondary structure prediction can be improved by applying constraints from nuclear magnetic resonance (NMR) experiments to a dynamic programming algorithm. Imino proton walks from NOESY spectra reveal double-stranded regions. Chemical shifts of protons in GH1, UH3, and UH5 of GU pairs, UH3, UH5, and AH2 of AU pairs, and GH1 of GC pairs were analyzed to identify constraints for the 5' to 3' directionality of base pairs in helices. The 5' to 3' directionality constraints were incorporated into an NMR-assisted prediction of secondary structure (NAPSS-CS) program. When it was tested on 18 structures, including nine pseudoknots, the sensitivity and positive predictive value were improved relative to those of three unrestrained programs. The prediction accuracy for the pseudoknots improved the most. The program also facilitates assignment of chemical shifts to individual nucleotides, a necessary step for determining three-dimensional structure.

  1. Simplified dark matter models with charged mediators: prospects for direct detection

    NASA Astrophysics Data System (ADS)

    Sandick, Pearl; Sinha, Kuver; Teng, Fei

    2016-10-01

    We consider direct detection prospects for a class of simplified models of fermionic dark matter (DM) coupled to left and right-handed Standard Model fermions via two charged scalar mediators with arbitrary mixing angle α. DM interactions with the nucleus are mediated by higher electromagnetic moments, which, for Majorana DM, is the anapole moment. After giving a full analytic calculation of the anapole moment, including its α dependence, and matching with limits in the literature, we compute the DM-nucleon scattering cross-section and show the LUX and future LZ constraints on the parameter space of these models. We then compare these results with constraints coming from F ermi-LAT continuum and line searches. Results in the supersymmetric limit of these simplified models are provided in all cases. We find that future direct detection experiments will be able to probe most of the parameter space of these models for O (100 - 200) GeV DM and lightest mediator mass ≲ O (5%) larger than the DM mass. The direct detection prospects dwindle for larger DM mass and larger mass gap between the DM and the lightest mediator mass, although appreciable regions are still probed for O (200) GeV DM and lightest mediator mass ≲ O (20%) larger than the DM mass. The direct detection bounds are also attenuated near certain "blind spots" in the parameter space, where the anapole moment is severely suppressed due to cancellation of different terms. We carefully study these blind spots and the associated F ermi-LAT signals in these regions.

  2. Direct optimization of LWIR systems for maximized detection range and minimized size and weight

    NASA Astrophysics Data System (ADS)

    Bates, Rob; Kubala, Kenneth

    2014-05-01

    With reductions in microbolometer size and cost, long-wave infrared (LWIR) systems are increasingly being developed for platforms with challenging size, weight, power, and cost (SWAP-C) constraints, such as helmet-mounted systems and unmanned vehicles. Past optimization of imaging systems toward the simultaneous objectives of improved stand-off detection and low size, weight, and power required an iterative, multi-disciplinary design process. Here we demonstrate the direct optimization of the full LWIR system model including the optics, sensor, signal processing, and display degrees of freedom with system level metrics including SWAP-C and detection range. The end result is a system with superior size and weight for a given detection range.

  3. Can the Existence of Dark Energy be Directly Detected?

    SciTech Connect

    Perl, Martin L.; /SLAC /KIPAC, Menlo Park

    2011-11-23

    The majority of astronomers and physicists accept the reality of dark energy and also believe that it can only be studied indirectly through observation of the motions of stars and galaxies. In this paper I open the experimental question of whether it is possible to directly detect dark energy through the presence of dark energy density. Two thirds of this paper outlines the major aspects of dark energy density as now comprehended by the astronomical and physics community. The final third summarizes various proposals for direct detection of dark energy density or its possible effects. At this time I do not have a fruitful answer to the question: Can the Existence of Dark Energy Be Directly Detected?

  4. Direct detection of classically undetectable dark matter through quantum decoherence

    NASA Astrophysics Data System (ADS)

    Riedel, C. Jess

    2013-12-01

    Although various pieces of indirect evidence about the nature of dark matter have been collected, its direct detection has eluded experimental searches despite extensive effort. If the mass of dark matter is below 1 MeV, it is essentially imperceptible to conventional detection methods because negligible energy is transferred to nuclei during collisions. Here I propose directly detecting dark matter through the quantum decoherence it causes rather than its classical effects, such as recoil or ionization. I show that quantum spatial superpositions are sensitive to low-mass dark matter that is inaccessible to classical techniques. This provides new independent motivation for matter interferometry with large masses, especially on spaceborne platforms. The apparent dark matter wind we experience as the Sun travels through the Milky Way ensures interferometers and related devices are directional detectors, and so are able to provide unmistakable evidence that decoherence has Galactic origins.

  5. Directed dynamical influence is more detectable with noise

    PubMed Central

    Jiang, Jun-Jie; Huang, Zi-Gang; Huang, Liang; Liu, Huan; Lai, Ying-Cheng

    2016-01-01

    Successful identification of directed dynamical influence in complex systems is relevant to significant problems of current interest. Traditional methods based on Granger causality and transfer entropy have issues such as difficulty with nonlinearity and large data requirement. Recently a framework based on nonlinear dynamical analysis was proposed to overcome these difficulties. We find, surprisingly, that noise can counterintuitively enhance the detectability of directed dynamical influence. In fact, intentionally injecting a proper amount of asymmetric noise into the available time series has the unexpected benefit of dramatically increasing confidence in ascertaining the directed dynamical influence in the underlying system. This result is established based on both real data and model time series from nonlinear ecosystems. We develop a physical understanding of the beneficial role of noise in enhancing detection of directed dynamical influence. PMID:27066763

  6. Maximum patch method for directional dark matter detection

    SciTech Connect

    Henderson, Shawn; Monroe, Jocelyn; Fisher, Peter

    2008-07-01

    Present and planned dark matter detection experiments search for WIMP-induced nuclear recoils in poorly known background conditions. In this environment, the maximum gap statistical method provides a way of setting more sensitive cross section upper limits by incorporating known signal information. We give a recipe for the numerical calculation of upper limits for planned directional dark matter detection experiments, that will measure both recoil energy and angle, based on the gaps between events in two-dimensional phase space.

  7. Direct Detection of Biotinylated Proteins by Mass Spectrometry

    PubMed Central

    2015-01-01

    Mass spectrometric strategies to identify protein subpopulations involved in specific biological functions rely on covalently tagging biotin to proteins using various chemical modification methods. The biotin tag is primarily used for enrichment of the targeted subpopulation for subsequent mass spectrometry (MS) analysis. A limitation of these strategies is that MS analysis does not easily discriminate unlabeled contaminants from the labeled protein subpopulation under study. To solve this problem, we developed a flexible method that only relies on direct MS detection of biotin-tagged proteins called “Direct Detection of Biotin-containing Tags” (DiDBiT). Compared with conventional targeted proteomic strategies, DiDBiT improves direct detection of biotinylated proteins ∼200 fold. We show that DiDBiT is applicable to several protein labeling protocols in cell culture and in vivo using cell permeable NHS-biotin and incorporation of the noncanonical amino acid, azidohomoalanine (AHA), into newly synthesized proteins, followed by click chemistry tagging with biotin. We demonstrate that DiDBiT improves the direct detection of biotin-tagged newly synthesized peptides more than 20-fold compared to conventional methods. With the increased sensitivity afforded by DiDBiT, we demonstrate the MS detection of newly synthesized proteins labeled in vivo in the rodent nervous system with unprecedented temporal resolution as short as 3 h. PMID:25117199

  8. Field-stepped direct detection electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Yu, Zhelin; Liu, Tengzhi; Elajaili, Hanan; Rinard, George A.; Eaton, Sandra S.; Eaton, Gareth R.

    2015-09-01

    The widest scan that had been demonstrated previously for rapid scan EPR was a 155 G sinusoidal scan. As the scan width increases, the voltage requirement across the resonating capacitor and scan coils increases dramatically and the background signal induced by the rapidly changing field increases. An alternate approach is needed to achieve wider scans. A field-stepped direct detection EPR method that is based on rapid-scan technology is now reported, and scan widths up to 6200 G have been demonstrated. A linear scan frequency of 5.12 kHz was generated with the scan driver described previously. The field was stepped at intervals of 0.01 to 1 G, depending on the linewidths in the spectra. At each field data for triangular scans with widths up to 11.5 G were acquired. Data from the triangular scans were combined by matching DC offsets for overlapping regions of successive scans. This approach has the following advantages relative to CW, several of which are similar to the advantages of rapid scan. (i) In CW if the modulation amplitude is too large, the signal is broadened. In direct detection field modulation is not used. (ii) In CW the small modulation amplitude detects only a small fraction of the signal amplitude. In direct detection each scan detects a larger fraction of the signal, which improves the signal-to-noise ratio. (iii) If the scan rate is fast enough to cause rapid scan oscillations, the slow scan spectrum can be recovered by deconvolution after the combination of segments. (iv) The data are acquired with quadrature detection, which permits phase correction in the post processing. (v) In the direct detection method the signal typically is oversampled in the field direction. The number of points to be averaged, thereby improving the signal-to-noise ratio, is determined in post processing based on the desired field resolution. A degased lithium phthalocyanine sample was used to demonstrate that the linear deconvolution procedure can be employed with

  9. Field-stepped direct detection electron paramagnetic resonance.

    PubMed

    Yu, Zhelin; Liu, Tengzhi; Elajaili, Hanan; Rinard, George A; Eaton, Sandra S; Eaton, Gareth R

    2015-09-01

    The widest scan that had been demonstrated previously for rapid scan EPR was a 155G sinusoidal scan. As the scan width increases, the voltage requirement across the resonating capacitor and scan coils increases dramatically and the background signal induced by the rapidly changing field increases. An alternate approach is needed to achieve wider scans. A field-stepped direct detection EPR method that is based on rapid-scan technology is now reported, and scan widths up to 6200G have been demonstrated. A linear scan frequency of 5.12kHz was generated with the scan driver described previously. The field was stepped at intervals of 0.01 to 1G, depending on the linewidths in the spectra. At each field data for triangular scans with widths up to 11.5G were acquired. Data from the triangular scans were combined by matching DC offsets for overlapping regions of successive scans. This approach has the following advantages relative to CW, several of which are similar to the advantages of rapid scan. (i) In CW if the modulation amplitude is too large, the signal is broadened. In direct detection field modulation is not used. (ii) In CW the small modulation amplitude detects only a small fraction of the signal amplitude. In direct detection each scan detects a larger fraction of the signal, which improves the signal-to-noise ratio. (iii) If the scan rate is fast enough to cause rapid scan oscillations, the slow scan spectrum can be recovered by deconvolution after the combination of segments. (iv) The data are acquired with quadrature detection, which permits phase correction in the post processing. (v) In the direct detection method the signal typically is oversampled in the field direction. The number of points to be averaged, thereby improving the signal-to-noise ratio, is determined in post processing based on the desired field resolution. A degased lithium phthalocyanine sample was used to demonstrate that the linear deconvolution procedure can be employed with field

  10. Indirect and direct detection prospect for TeV dark matter in the nine parameter MSSM

    NASA Astrophysics Data System (ADS)

    Cabrera-Catalan, Maria Eugenia; Ando, Shin'ichiro; Weniger, Christoph; Zandanel, Fabio

    2015-08-01

    We investigate the prospects of indirect and direct dark matter searches within the minimal supersymmetric standard model with nine parameters (MSSM-9). These nine parameters include three gaugino masses, Higgs, slepton and squark masses, all treated independently. We perform a Bayesian Monte Carlo scan of the parameter space taking into consideration all available particle physics constraints such as the Higgs mass of 126 GeV, upper limits on the scattering cross section from direct-detection experiments, and assuming that the MSSM-9 provides all the dark matter abundance through a thermal freeze-out mechanism. Within this framework we find the two most probable regions for dark matter: 1-TeV Higgsino-like and 3-TeV Wino-like neutralinos. We discuss prospects for future indirect [in particular the Cherenkov Telescope Array (CTA)] and direct detection experiments. We find that for slightly contracted dark matter profiles in our Galaxy, which can be caused by the effects of baryonic infall in the Galactic center, CTA will be able to probe a large fraction of the remaining allowed region in synergy with future direct detection experiments like XENON-1T.

  11. Analysis of the theoretical bias in dark matter direct detection

    SciTech Connect

    Catena, Riccardo

    2014-09-01

    Fitting the model ''A'' to dark matter direct detection data, when the model that underlies the data is ''B'', introduces a theoretical bias in the fit. We perform a quantitative study of the theoretical bias in dark matter direct detection, with a focus on assumptions regarding the dark matter interactions, and velocity distribution. We address this problem within the effective theory of isoscalar dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle. We analyze 24 benchmark points in the parameter space of the theory, using frequentist and Bayesian statistical methods. First, we simulate the data of future direct detection experiments assuming a momentum/velocity dependent dark matter-nucleon interaction, and an anisotropic dark matter velocity distribution. Then, we fit a constant scattering cross section, and an isotropic Maxwell-Boltzmann velocity distribution to the simulated data, thereby introducing a bias in the analysis. The best fit values of the dark matter particle mass differ from their benchmark values up to 2 standard deviations. The best fit values of the dark matter-nucleon coupling constant differ from their benchmark values up to several standard deviations. We conclude that common assumptions in dark matter direct detection are a source of potentially significant bias.

  12. Comparison of direct and heterodyne detection optical intersatellite communication links

    NASA Technical Reports Server (NTRS)

    Chen, C. C.; Gardner, C. S.

    1987-01-01

    The performance of direct and heterodyne detection optical intersatellite communication links are evaluated and compared. It is shown that the performance of optical links is very sensitive to the pointing and tracking errors at the transmitter and receiver. In the presence of random pointing and tracking errors, optimal antenna gains exist that will minimize the required transmitter power. In addition to limiting the antenna gains, random pointing and tracking errors also impose a power penalty in the link budget. This power penalty is between 1.6 to 3 dB for a direct detection QPPM link, and 3 to 5 dB for a heterodyne QFSK system. For the heterodyne systems, the carrier phase noise presents another major factor of performance degradation that must be considered. In contrast, the loss due to synchronization error is small. The link budgets for direct and heterodyne detection systems are evaluated. It is shown that, for systems with large pointing and tracking errors, the link budget is dominated by the spatial tracking error, and the direct detection system shows a superior performance because it is less sensitive to the spatial tracking error. On the other hand, for systems with small pointing and tracking jitters, the antenna gains are in general limited by the launch cost, and suboptimal antenna gains are often used in practice. In which case, the heterodyne system has a slightly higher power margin because of higher receiver sensitivity.

  13. Channel simulation for direct-detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct-detection optical communication system. The system is capable of providing signal fading statistics which obey log-normal, beta, Rayleigh, Ricean, or chi-square density functions. Experimental tests of the performance of the channel simulator are presented.

  14. Channel simulation for direct detection optical communication systems

    NASA Technical Reports Server (NTRS)

    Tycz, M.; Fitzmaurice, M. W.

    1974-01-01

    A technique is described for simulating the random modulation imposed by atmospheric scintillation and transmitter pointing jitter on a direct detection optical communication system. The system is capable of providing signal fading statistics which obey log normal, beta, Rayleigh, Ricean or chi-squared density functions. Experimental tests of the performance of the Channel Simulator are presented.

  15. Sol-gel matrices for direct colorimetric detection of analytes

    DOEpatents

    Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey

    2000-01-01

    The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

  16. Sol-Gel Matrices For Direct Colorimetric Detection Of Analytes

    DOEpatents

    Charych, Deborah H.; Sasaki, Darryl; Yamanaka, Stacey

    2002-11-26

    The present invention relates to methods and compositions for the direct detection of analytes using color changes that occur in immobilized biopolymeric material in response to selective binding of analytes to their surface. In particular, the present invention provides methods and compositions related to the encapsulation of biopolymeric material into metal oxide glass using the sol-gel method.

  17. Halo-Independent Comparison of Direct Dark Matter Detection Data

    DOE PAGESBeta

    Del Nobile, Eugenio

    2014-01-01

    We review the halo-independent formalism that allows comparing data from different direct dark matter detection experiments without making assumptions on the properties of the dark matter halo. We apply this method to spin-independent WIMP-nuclei interactions, for both isospin-conserving and isospin-violating couplings, and to WIMPs interacting through an anomalous magnetic moment.

  18. Direct detection of a microlens in the Milky Way.

    PubMed

    Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Cook, K H; Drake, A J; Freeman, K C; Geha, M; Griest, K; Keller, S C; Lehner, M J; Marshall, S L; Minniti, D; Nelson, C A; Peterson, B A; Popowski, P; Pratt, M R; Quinn, P J; Stubbs, C W; Sutherland, W; Tomaney, A B; Vandehei, T; Welch, D

    2001-12-01

    The nature of dark matter remains mysterious, with luminous material accounting for at most approximately 25 per cent of the baryons in the Universe. We accordingly undertook a survey looking for the microlensing of stars in the Large Magellanic Cloud (LMC) to determine the fraction of Galactic dark matter contained in massive compact halo objects (MACHOs). The presence of the dark matter would be revealed by gravitational lensing of the light from an LMC star as the foreground dark matter moves across the line of sight. The duration of the lensing event is the key observable parameter, but gives non-unique solutions when attempting to estimate the mass, distance and transverse velocity of the lens. The survey results to date indicate that between 8 and 50 per cent of the baryonic mass of the Galactic halo is in the form of MACHOs (ref. 3), but removing the degeneracy by identifying a lensing object would tighten the constraints on the mass in MACHOs. Here we report a direct image of a microlens, revealing it to be a nearby low-mass star in the disk of the Milky Way. This is consistent with the expected frequency of nearby stars acting as lenses, and demonstrates a direct determination of a lens mass from a microlensing event. Complete solutions such as this for halo microlensing events will probe directly the nature of the MACHOs.

  19. Direct detection of a microlens in the Milky Way.

    PubMed

    Alcock, C; Allsman, R A; Alves, D R; Axelrod, T S; Becker, A C; Bennett, D P; Cook, K H; Drake, A J; Freeman, K C; Geha, M; Griest, K; Keller, S C; Lehner, M J; Marshall, S L; Minniti, D; Nelson, C A; Peterson, B A; Popowski, P; Pratt, M R; Quinn, P J; Stubbs, C W; Sutherland, W; Tomaney, A B; Vandehei, T; Welch, D

    2001-12-01

    The nature of dark matter remains mysterious, with luminous material accounting for at most approximately 25 per cent of the baryons in the Universe. We accordingly undertook a survey looking for the microlensing of stars in the Large Magellanic Cloud (LMC) to determine the fraction of Galactic dark matter contained in massive compact halo objects (MACHOs). The presence of the dark matter would be revealed by gravitational lensing of the light from an LMC star as the foreground dark matter moves across the line of sight. The duration of the lensing event is the key observable parameter, but gives non-unique solutions when attempting to estimate the mass, distance and transverse velocity of the lens. The survey results to date indicate that between 8 and 50 per cent of the baryonic mass of the Galactic halo is in the form of MACHOs (ref. 3), but removing the degeneracy by identifying a lensing object would tighten the constraints on the mass in MACHOs. Here we report a direct image of a microlens, revealing it to be a nearby low-mass star in the disk of the Milky Way. This is consistent with the expected frequency of nearby stars acting as lenses, and demonstrates a direct determination of a lens mass from a microlensing event. Complete solutions such as this for halo microlensing events will probe directly the nature of the MACHOs. PMID:11740553

  20. Detection of Laser Optic Defects Using Gradient Direction Matching

    SciTech Connect

    Chen, B Y; Kegelmeyer, L M; Liebman, J A; Salmon, J T; Tzeng, J; Paglieroni, D W

    2005-12-14

    That National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) will be the world's largest and most energetic laser. It has thousands of optics and depends heavily on the quality and performance of these optics. Over the past several years, we have developed the NIF Optics Inspection Analysis System that automatically finds defects in a specific optic by analyzing images taken of that optic. This paper describes a new and complementary approach for the automatic detection of defects based on detecting the diffraction ring patterns in downstream optic images caused by defects in upstream optics. Our approach applies a robust pattern matching algorithm for images called Gradient Direction Matching (GDM). GDM compares the gradient directions (the direction of flow from dark to light) of pixels in a test image to those of a specified model and identifies regions in the test image whose gradient directions are most in line with those of the specified model. For finding rings, we use luminance disk models whose pixels have gradient directions all pointing toward the center of the disk. After GDM identifies potential rings locations, we rank these rings by how well they fit the theoretical diffraction ring pattern equation. We perform false alarm mitigation by throwing out rings of low fit. A byproduct of this fitting procedure is an estimate of the size of the defect and its distance from the image plane. We demonstrate the potential effectiveness of this approach by showing examples of rings detected in real images of NIF optics.

  1. Direct Detection of Sub-GeV Dark Matter

    SciTech Connect

    Essig, Rouven; Mardon, Jeremy; Volansky, Tomer

    2012-03-20

    Direct detection strategies are proposed for dark matter particles with MeV to GeV mass. In this largely unexplored mass range, dark matter scattering with electrons can cause single-electron ionization signals, which are detectable with current technology. Ultraviolet photons, individual ions, and heat are interesting alternative signals. Focusing on ionization, we calculate the expected dark matter scattering rates and estimate the sensitivity of possible experiments. Backgrounds that may be relevant are discussed. Theoretically interesting models can be probed with existing technologies, and may even be within reach using ongoing direct detection experiments. Significant improvements in sensitivity should be possible with dedicated experiments, opening up a window to new regions in dark matter parameter space.

  2. An antenna for directional detection of WISPy dark matter

    NASA Astrophysics Data System (ADS)

    Jaeckel, Joerg; Redondo, Javier

    2013-11-01

    It is an intriguing possibility that the cold dark matter of the Universe may consist of very light and very weakly interacting particles such as axion(-like particles) and hidden photons. This opens up (but also requires) new techniques for direct detection. One possibility is to use reflecting surfaces to facilitate the conversion of dark matter into photons, which can be concentrated in a detector with a suitable geometry. In this note we show that this technique also allows for directional detection and inference of the full vectorial velocity spectrum of the dark matter particles. We also note that the non-vanishing velocity of dark matter particles is relevant for the conception of (non-directional) discovery experiments and outline relevant features.

  3. Dark matter directional detection in non-relativistic effective theories

    SciTech Connect

    Catena, Riccardo

    2015-07-20

    We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF{sub 4}, CS{sub 2} and {sup 3}He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments.

  4. Reliable detection of directional couplings using rank statistics.

    PubMed

    Chicharro, Daniel; Andrzejak, Ralph G

    2009-08-01

    To detect directional couplings from time series various measures based on distances in reconstructed state spaces were introduced. These measures can, however, be biased by asymmetries in the dynamics' structure, noise color, or noise level, which are ubiquitous in experimental signals. Using theoretical reasoning and results from model systems we identify the various sources of bias and show that most of them can be eliminated by an appropriate normalization. We furthermore diminish the remaining biases by introducing a measure based on ranks of distances. This rank-based measure outperforms existing distance-based measures concerning both sensitivity and specificity for directional couplings. Therefore, our findings are relevant for a reliable detection of directional couplings from experimental signals.

  5. Dark matter directional detection in non-relativistic effective theories

    SciTech Connect

    Catena, Riccardo

    2015-07-01

    We extend the formalism of dark matter directional detection to arbitrary one-body dark matter-nucleon interactions. The new theoretical framework generalizes the one currently used, which is based on 2 types of dark matter-nucleon interaction only. It includes 14 dark matter-nucleon interaction operators, 8 isotope-dependent nuclear response functions, and the Radon transform of the first 2 moments of the dark matter velocity distribution. We calculate the recoil energy spectra at dark matter directional detectors made of CF{sub 4}, CS{sub 2} and {sup 3}He for the 14 dark matter-nucleon interactions, using nuclear response functions recently obtained through numerical nuclear structure calculations. We highlight the new features of the proposed theoretical framework, and present our results for a spherical dark matter halo and for a stream of dark matter particles. This study lays the foundations for model independent analyses of dark matter directional detection experiments.

  6. Direct immunoassay for detection of salmonellae in foods and feeds.

    PubMed

    Anderson, J M; Hartman, P A

    1985-05-01

    A direct enzyme immunoassay (EIA) with polyclonal antibodies was developed for detecting salmonellae in foods and feeds. Salmonella cells were attached firmly to the wells of polystyrene microtitration plates with a capture-antibody technique. Spicer-Edwards anti-H immunoglobulin G was bound to protein A-beta-D-galactosidase to serve as the signal; 4-methylumbelliferyl-beta-D-galactoside was used as the substrate. The sensitivity threshold was 10(7) cells per ml. Direct EIA, indirect EIA, and pure-culture techniques were compared by using 48 samples of naturally contaminated foods and feeds. The direct EIA was more sensitive than the indirect EIA or pure-culture technique. Food samples were analyzed within 3 working days, and 32 samples were tested simultaneously in a single 96-well microtitration plate. False-positive or false-negative results did not pose a problem. This direct EIA is sensitive, rapid, and amenable to automation.

  7. Direct detection of sub-GeV dark matter with semiconductor targets

    NASA Astrophysics Data System (ADS)

    Essig, Rouven; Fernández-Serra, Marivi; Mardon, Jeremy; Soto, Adrián; Volansky, Tomer; Yu, Tien-Tien

    2016-05-01

    Dark matter in the sub-GeV mass range is a theoretically motivated but largely unexplored paradigm. Such light masses are out of reach for conventional nuclear recoil direct detection experiments, but may be detected through the small ionization signals caused by dark matter-electron scattering. Semiconductors are well-studied and are particularly promising target materials because their {O} (1 eV) band gaps allow for ionization signals from dark matter particles as light as a few hundred keV. Current direct detection technologies are being adapted for dark matter-electron scattering. In this paper, we provide the theoretical calculations for dark matter-electron scattering rate in semiconductors, overcoming several complications that stem from the many-body nature of the problem. We use density functional theory to numerically calculate the rates for dark matter-electron scattering in silicon and germanium, and estimate the sensitivity for upcoming experiments such as DAMIC and SuperCDMS. We find that the reach for these upcoming experiments has the potential to be orders of magnitude beyond current direct detection constraints and that sub-GeV dark matter has a sizable modulation signal. We also give the first direct detection limits on sub-GeV dark matter from its scattering off electrons in a semiconductor target (silicon) based on published results from DAMIC. We make available publicly our code, QEdark , with which we calculate our results. Our results can be used by experimental collaborations to calculate their own sensitivities based on their specific setup. The searches we propose will probe vast new regions of unexplored dark matter model and parameter space.

  8. Direct detection of sub-GeV dark matter with semiconductor targets

    DOE PAGESBeta

    Essig, Rouven; Fernández-Serra, Marivi; Mardon, Jeremy; Soto, Adrián; Volansky, Tomer; Yu, Tien -Tien

    2016-05-09

    Dark matter in the sub-GeV mass range is a theoretically motivated but largely unexplored paradigm. Such light masses are out of reach for conventional nuclear recoil direct detection experiments, but may be detected through the small ionization signals caused by dark matter-electron scattering. Semiconductors are well-studied and are particularly promising target materials because their O(1 eV) band gaps allow for ionization signals from dark matter particles as light as a few hundred keV. Current direct detection technologies are being adapted for dark matter-electron scattering. In this paper, we provide the theoretical calculations for dark matter-electron scattering rate in semiconductors, overcomingmore » several complications that stem from the many-body nature of the problem. We use density functional theory to numerically calculate the rates for dark matter-electron scattering in silicon and germanium, and estimate the sensitivity for upcoming experiments such as DAMIC and SuperCDMS. We find that the reach for these upcoming experiments has the potential to be orders of magnitude beyond current direct detection constraints and that sub-GeV dark matter has a sizable modulation signal. We also give the first direct detection limits on sub-GeV dark matter from its scattering off electrons in a semiconductor target (silicon) based on published results from DAMIC. We make available publicly our code, QEdark, with which we calculate our results. Our results can be used by experimental collaborations to calculate their own sensitivities based on their specific setup. In conclusion, the searches we propose will probe vast new regions of unexplored dark matter model and parameter space.« less

  9. Informational constraints on the emergence of passing direction in the team sport of futsal.

    PubMed

    Corrêa, Umberto Cesar; Vilar, Luís; Davids, Keith; Renshaw, Ian

    2014-01-01

    This study investigated compound spatial and temporal measures of interpersonal interactions purported to constrain the emergence of affordances for passing direction in the team sport of futsal. For this purpose, attacker-defender interactions in 37 sequences of play from a futsal competition in which 24 male professional players participated (M=30.04 years, SD=4.10) were filmed and analysed using TACTO software. Relative angle data were used as measures to study coordination tendencies that emerged between players during performance. Results showed that the direction for a pass emerged from relative angles between: (1) the vector from a ball carrier to ball receiver and the vector from the ball carrier to the nearest defender (70°) (p<0.01) and (2) the vector from a ball carrier to ball receiver and the vector from the ball carrier to a ball receiver's nearest defender (31°) (p < 0.01). Furthermore, passing direction was also constrained by temporal information from the emergence of both angles, since the pass was performed to attacker-defender dyads with the highest velocities of these angles (p < 0.05). Results suggested that decisions on selecting the direction of a pass in the team sport of futsal emerged at critical values of these key compound motion measures.

  10. An Automated Directed Spectral Search Methodology for Small Target Detection

    NASA Astrophysics Data System (ADS)

    Grossman, Stanley I.

    Much of the current efforts in remote sensing tackle macro-level problems such as determining the extent of wheat in a field, the general health of vegetation or the extent of mineral deposits in an area. However, for many of the remaining remote sensing challenges being studied currently, such as border protection, drug smuggling, treaty verification, and the war on terror, most targets are very small in nature - a vehicle or even a person. While in typical macro-level problems the objective vegetation is in the scene, for small target detection problems it is not usually known if the desired small target even exists in the scene, never mind finding it in abundance. The ability to find specific small targets, such as vehicles, typifies this problem. Complicating the analyst's life, the growing number of available sensors is generating mountains of imagery outstripping the analysts' ability to visually peruse them. This work presents the important factors influencing spectral exploitation using multispectral data and suggests a different approach to small target detection. The methodology of directed search is presented, including the use of scene-modeled spectral libraries, various search algorithms, and traditional statistical and ROC curve analysis. The work suggests a new metric to calibrate analysis labeled the analytic sweet spot as well as an estimation method for identifying the sweet spot threshold for an image. It also suggests a new visualization aid for highlighting the target in its entirety called nearest neighbor inflation (NNI). It brings these all together to propose that these additions to the target detection arena allow for the construction of a fully automated target detection scheme. This dissertation next details experiments to support the hypothesis that the optimum detection threshold is the analytic sweet spot and that the estimation method adequately predicts it. Experimental results and analysis are presented for the proposed directed

  11. Hunting electroweakinos at future hadron colliders and direct detection experiments

    NASA Astrophysics Data System (ADS)

    di Cortona, Giovanni Grilli

    2015-05-01

    We analyse the mass reach for electroweakinos at future hadron colliders and their interplay with direct detection experiments. Motivated by the LHC data, we focus on split supersymmetry models with different electroweakino spectra. We find for example that a 100 TeV collider may explore Winos up to ˜ 7 TeV in low scale gauge mediation models or thermal Wino dark matter around 3 TeV in models of anomaly mediation with long-lived Winos. We show moreover how collider searches and direct detection experiments have the potential to cover large part of the parameter space even in scenarios where the lightest neutralino does not contribute to the whole dark matter relic density.

  12. Direct detection of CH/pi interactions in proteins.

    PubMed

    Plevin, Michael J; Bryce, David L; Boisbouvier, Jérôme

    2010-06-01

    XH/pi interactions make important contributions to biomolecular structure and function. These weakly polar interactions, involving pi-system acceptor groups, are usually identified from the three-dimensional structures of proteins. Here, nuclear magnetic resonance spectroscopy has been used to directly detect methyl/pi (Me/pi) interactions in proteins at atomic resolution. Density functional theory calculations predict the existence of weak scalar (J) couplings between nuclei involved in Me/pi interactions. Using an optimized isotope-labelling strategy, these J couplings have been detected in proteins using nuclear magnetic resonance spectroscopy. The resulting spectra provide direct experimental evidence of Me/pi interactions in proteins and allow a simple and unambiguous assignment of donor and acceptor groups. The use of nuclear magnetic resonance spectroscopy is an elegant way to identify and experimentally characterize Me/pi interactions in proteins without the need for arbitrary geometric descriptions or pre-existing three-dimensional structures. PMID:20489715

  13. Dark matter effective field theory scattering in direct detection experiments

    SciTech Connect

    Schneck, K.

    2015-05-01

    We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  14. Dark matter effective field theory scattering in direct detection experiments

    DOE PAGESBeta

    Schneck, K.

    2015-05-01

    We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implicationsmore » of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.« less

  15. Directional detection of dark matter in universal bound states

    SciTech Connect

    Laha, Ranjan

    2015-10-06

    It has been suggested that several small-scale structure anomalies in Λ CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angular recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.

  16. (In)Direct detection of boosted dark matter

    NASA Astrophysics Data System (ADS)

    Agashe, Kaustubh; Cui, Yanou; Necib, Lina; Thaler, Jesse

    2016-05-01

    We present a new multi-component dark matter model with a novel experimental signature that mimics neutral current interactions at neutrino detectors. In our model, the dark matter is composed of two particles, a heavier dominant component that annihilates to produce a boosted lighter component that we refer to as boosted dark matter. The lighter component is relativistic and scatters off electrons in neutrino experiments to produce Cherenkov light. This model combines the indirect detection of the dominant component with the direct detection of the boosted dark matter. Directionality can be used to distinguish the dark matter signal from the atmospheric neutrino background. We discuss the viable region of parameter space in current and future experiments.

  17. Dark matter effective field theory scattering in direct detection experiments

    NASA Astrophysics Data System (ADS)

    Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.; SuperCDMS Collaboration

    2015-05-01

    We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  18. Dark matter effective field theory scattering in direct detection experiments

    SciTech Connect

    Schneck, K.; Cabrera, B.; Cerdeno, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, Priscilla B.; Daal, M.; Di Stefano, P. C.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, Jeter C.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, W.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.

    2015-05-01

    We examine the consequences of the effective eld theory (EFT) of dark matter-nucleon scattering or current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral di*erences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  19. Dark matter effective field theory scattering in direct detection experiments

    SciTech Connect

    Schneck, K.; Cabrera, B.; Cerdeño, D. G.; Mandic, V.; Rogers, H. E.; Agnese, R.; Anderson, A. J.; Asai, M.; Balakishiyeva, D.; Barker, D.; Basu Thakur, R.; Bauer, D. A.; Billard, J.; Borgland, A.; Brandt, D.; Brink, P. L.; Bunker, R.; Caldwell, D. O.; Calkins, R.; Chagani, H.; Chen, Y.; Cooley, J.; Cornell, B.; Crewdson, C. H.; Cushman, P.; Daal, M.; Di Stefano, P. C. F.; Doughty, T.; Esteban, L.; Fallows, S.; Figueroa-Feliciano, E.; Godfrey, G. L.; Golwala, S. R.; Hall, J.; Harris, H. R.; Hofer, T.; Holmgren, D.; Hsu, L.; Huber, M. E.; Jardin, D. M.; Jastram, A.; Kamaev, O.; Kara, B.; Kelsey, M. H.; Kennedy, A.; Leder, A.; Loer, B.; Lopez Asamar, E.; Lukens, P.; Mahapatra, R.; McCarthy, K. A.; Mirabolfathi, N.; Moffatt, R. A.; Morales Mendoza, J. D.; Oser, S. M.; Page, K.; Page, W. A.; Partridge, R.; Pepin, M.; Phipps, A.; Prasad, K.; Pyle, M.; Qiu, H.; Rau, W.; Redl, P.; Reisetter, A.; Ricci, Y.; Roberts, A.; Saab, T.; Sadoulet, B.; Sander, J.; Schnee, R. W.; Scorza, S.; Serfass, B.; Shank, B.; Speller, D.; Toback, D.; Upadhyayula, S.; Villano, A. N.; Welliver, B.; Wilson, J. S.; Wright, D. H.; Yang, X.; Yellin, S.; Yen, J. J.; Young, B. A.; Zhang, J.

    2015-05-18

    We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. Here. we demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. In conclusion, we discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

  20. Direct detection of classically undetectable dark matter through quantum decoherence

    NASA Astrophysics Data System (ADS)

    Riedel, C. Jess

    2014-03-01

    Although various pieces of indirect evidence about the nature of dark matter have been collected, its direct detection has eluded experimental searches despite extensive effort. If the mass of dark matter is below 1 MeV, it is essentially imperceptible to conventional detection methods because negligible energy is transferred to nuclei during collisions. Here I propose directly detecting dark matter through the quantum decoherence it causes rather than its classical effects such as recoil or ionization. I show that quantum spatial superpositions are sensitive to low-mass dark matter which is inaccessible to classical techniques. This provides new independent motivation for matter interferometry with large masses, especially on spaceborne platforms. The apparent dark matter wind we experience as the Sun travels through the Milky Way ensures interferometers and related devices are directional detectors, and so are able to provide unmistakable evidence that decoherence has galactic origins. This research was partially supported by the U.S. Department of Energy through the LANL/LDRD program, and by the John Templeton Foundation through grant number 21484.

  1. Direct detection portals for self-interacting dark matter

    NASA Astrophysics Data System (ADS)

    Kaplinghat, Manoj; Tulin, Sean; Yu, Hai-Bo

    2014-02-01

    Dark matter self-interactions can affect the small scale structure of the Universe, reducing the central densities of dwarfs and low surface brightness galaxies in accord with observations. From a particle physics point of view, this points toward the existence of a 1-100 MeV particle in the dark sector that mediates self-interactions. Since mediator particles will generically couple to the Standard Model, direct detection experiments provide sensitive probes of self-interacting dark matter. We consider three minimal mechanisms for coupling the dark and visible sectors: photon kinetic mixing, Z boson mass mixing, and the Higgs portal. Self-interacting dark matter motivates a new benchmark paradigm for direct detection via momentum-dependent interactions, and ton-scale experiments will cover astrophysically motivated parameter regimes that are unconstrained by current limits. Direct detection is a complementary avenue to constrain velocity-dependent self-interactions that evade astrophysical bounds from larger scales, such as those from the bullet cluster.

  2. Direct Imaging Detectability of Tidally Heated ExoMoons (THEM)

    NASA Astrophysics Data System (ADS)

    Turner, E. L.; Peters, M. A.

    2014-03-01

    Existing and planned ground and space-based telescopes are capable of directly imaging plausible tidally heated exomoons orbiting gas-giant exoplanets. Tidally heated exomoons can easily be far more luminous than their host exoplanet and as much as 0.001 as bright as the system's stellar primary. Because emission from exomoons can be powered by tidal forces, their luminosities are independent of their separations from the system's stellar primary. Furthermore, high surface temperatures can occur in systems that are billions of years old. Tidally heated exomoons may thus be far easier targets for direct imaging studies than giant exoplanets that must be both young and at a large projected separation (typically at least tens of AU) from their primary to be accessible to direct imaging currently. For example, the (warm) Spitzer Space Telescope and the next generation of ground based instruments could detect an exomoon roughly the size of the Earth at a temperature of ~600 K and a distance ~5 parsecs in IR bands; in more favorable cases, detections are possible at distances of tens of parsecs. Future mid-infrared space telescopes, such as JWST and SPICA, will be capable of directly imaging tidally heated exomoons around the nearest two dozen stars with brightness temperatures of ~300 K and sizes similar to the Earth orbiting beyond 10 AU at a 5 sigma confidence level in a 10^4 second integration. It is also possible that some already imaged exoplanets are actually tidally heated exomoons or blends of such objects with hot young planets. If THEM exist and are sufficiently common (and thus nearby), it may be easier to directly image an exomoon with surface conditions that allow the existence of liquid water than it will be to resolve an Earth-like planet in the classical Habitable Zone of its primary. Preliminary results of a search for THEM in Spitzer archival images of nearby stars indicate that these data are sufficient to allow the detection of plausible THEM.

  3. Direct Exoplanet Imaging with JWST NIRCam: Low-Mass Stars, Low-Mass Planets, and Critical Constraints on Planet Formation

    NASA Astrophysics Data System (ADS)

    Schlieder, Joshua E.; Meyer, Michael; Reggiani, Maddalena; Quanz, Sascha; Beichman, Charles A.; Greene, Thomas P.; Burrows, Adam Seth

    2016-01-01

    As next generation exoplanet imagers are making their first discoveries, the largest population of stars in the Galaxy, the M dwarfs, are largely unaccounted for in their surveys. However, RV trends and micro lensing have revealed that M dwarfs host a substantial population of Neptune to Jupiter mass planets between ~1-10 AU. The unprecedented sensitivity of NIRCam on the JWST provides direct access to this population of gas-giants. A NIRCam 3 - 5 μm survey for such planets will place critical constraints on planet formation by: 1) measuring the luminosities of young, sub-Jupiter mass planets, 2) providing constraints on the peak in the companion surface density vs. separation distribution, and 3) measuring the frequency of ≤Jupiter mass giants in the outskirts of these systems (>10 AU). We have carefully constructed a sample of nearby, young, late-type stars, performed NIRCam survey simulations, and will report on the expected yield and advantages of JWST compared to current ground based capabilities.

  4. (In)direct detection of boosted dark matter

    SciTech Connect

    Agashe, Kaustubh; Cui, Yanou; Necib, Lina; Thaler, Jesse E-mail: cuiyo@umd.edu E-mail: jthaler@mit.edu

    2014-10-01

    We initiate the study of novel thermal dark matter (DM) scenarios where present-day annihilation of DM in the galactic center produces boosted stable particles in the dark sector. These stable particles are typically a subdominant DM component, but because they are produced with a large Lorentz boost in this process, they can be detected in large volume terrestrial experiments via neutral-current-like interactions with electrons or nuclei. This novel DM signal thus combines the production mechanism associated with indirect detection experiments (i.e. galactic DM annihilation) with the detection mechanism associated with direct detection experiments (i.e. DM scattering off terrestrial targets). Such processes are generically present in multi-component DM scenarios or those with non-minimal DM stabilization symmetries. As a proof of concept, we present a model of two-component thermal relic DM, where the dominant heavy DM species has no tree-level interactions with the standard model and thus largely evades direct and indirect DM bounds. Instead, its thermal relic abundance is set by annihilation into a subdominant lighter DM species, and the latter can be detected in the boosted channel via the same annihilation process occurring today. Especially for dark sector masses in the 10 MeV–10 GeV range, the most promising signals are electron scattering events pointing toward the galactic center. These can be detected in experiments designed for neutrino physics or proton decay, in particular Super-K and its upgrade Hyper-K, as well as the PINGU/MICA extensions of IceCube. This boosted DM phenomenon highlights the distinctive signatures possible from non-minimal dark sectors.

  5. (In)direct detection of boosted dark matter

    NASA Astrophysics Data System (ADS)

    Agashe, Kaustubh; Cui, Yanou; Necib, Lina; Thaler, Jesse

    2014-10-01

    We initiate the study of novel thermal dark matter (DM) scenarios where present-day annihilation of DM in the galactic center produces boosted stable particles in the dark sector. These stable particles are typically a subdominant DM component, but because they are produced with a large Lorentz boost in this process, they can be detected in large volume terrestrial experiments via neutral-current-like interactions with electrons or nuclei. This novel DM signal thus combines the production mechanism associated with indirect detection experiments (i.e. galactic DM annihilation) with the detection mechanism associated with direct detection experiments (i.e. DM scattering off terrestrial targets). Such processes are generically present in multi-component DM scenarios or those with non-minimal DM stabilization symmetries. As a proof of concept, we present a model of two-component thermal relic DM, where the dominant heavy DM species has no tree-level interactions with the standard model and thus largely evades direct and indirect DM bounds. Instead, its thermal relic abundance is set by annihilation into a subdominant lighter DM species, and the latter can be detected in the boosted channel via the same annihilation process occurring today. Especially for dark sector masses in the 10 MeV-10 GeV range, the most promising signals are electron scattering events pointing toward the galactic center. These can be detected in experiments designed for neutrino physics or proton decay, in particular Super-K and its upgrade Hyper-K, as well as the PINGU/MICA extensions of IceCube. This boosted DM phenomenon highlights the distinctive signatures possible from non-minimal dark sectors.

  6. Superconducting Nuclear Recoil Sensor for Directional Dark Matter Detection

    NASA Astrophysics Data System (ADS)

    Junghans, Ann; Baldwin, Kevin; Hehlen, Markus; Lafler, Randy; Loomba, Dinesh; Phan, Nguyen; Weisse-Bernstein, Nina

    The Universe consists of 72% dark energy, 23% dark matter and only 5% of ordinary matter. One of the greatest challenges of the scientific community is to understand the nature of dark matter. Current models suggest that dark matter is made up of slowly moving, weakly interacting massive particles (WIMPs). But detecting WIMPs is challenging, as their expected signals are small and rare compared to the large background that can mimic the signal. The largest and most robust unique signature that sets them apart from other particles is the day-night variation of the directionality of dark matter on Earth. This modulation could be observed with a direction-sensitive detector and hence, would provide an unambiguous signature for the galactic origin of WIMPs. There are many studies underway to attempt to detect WIMPs both directly and indirectly, but solid-state WIMP detectors are widely unexplored although they would present many advantages to prevalent detectors that use large volumes of low pressure gas. We present first results of a novel multi-layered architecture, in which WIMPs would interact primarily with solid layers to produce nuclear recoils that then induce measureable voltage pulses in adjacent superconductor layers. This work was supported by the U.S. Department of Energy through the LANL Laboratory Directed Research and Development Program.

  7. New constraints on direct collapse black hole formation in the early Universe

    NASA Astrophysics Data System (ADS)

    Agarwal, Bhaskar; Smith, Britton; Glover, Simon; Natarajan, Priyamvada; Khochfar, Sadegh

    2016-07-01

    Direct collapse black holes (DCBH) have been proposed as a solution to the challenge of assembling supermassive black holes by z > 6 to explain the bright quasars observed at this epoch. The formation of a DCBH seed with MBH ˜ 104-5 M⊙ requires a pristine atomic-cooling halo to be illuminated by an external radiation field that is sufficiently strong to entirely suppress H2 cooling in the halo. Many previous studies have attempted to constrain the critical specific intensity that is likely required to suppress H2 cooling, denoted as Jcrit. However, these studies have typically assumed that the incident external radiation field can be modelled with a blackbody spectrum. Under this assumption, it is possible to derive a unique value for Jcrit that depends only on the temperature of the blackbody. In this study we consider a more realistic spectral energy distribution (SED) for the external source of radiation that depends entirely on its star formation history and age. The rate of destruction of the species responsible for suppressing molecular hydrogen cooling depends on the detailed shape of the SED. Therefore the value of Jcrit is tied to the shape of the incident SED of the neighbouring galaxy. We fit a parametric form to the rates of destruction of H2 and H- that permit direct collapse. Owing to this, we find that Jcrit is not a fixed threshold but can lie anywhere in the range Jcrit ˜ 0.5-103, depending on the details of the source stellar population.

  8. A generating set direct search augmented Lagrangian algorithm for optimization with a combination of general and linear constraints.

    SciTech Connect

    Lewis, Robert Michael (College of William and Mary, Williamsburg, VA); Torczon, Virginia Joanne (College of William and Mary, Williamsburg, VA); Kolda, Tamara Gibson

    2006-08-01

    We consider the solution of nonlinear programs in the case where derivatives of the objective function and nonlinear constraints are unavailable. To solve such problems, we propose an adaptation of a method due to Conn, Gould, Sartenaer, and Toint that proceeds by approximately minimizing a succession of linearly constrained augmented Lagrangians. Our modification is to use a derivative-free generating set direct search algorithm to solve the linearly constrained subproblems. The stopping criterion proposed by Conn, Gould, Sartenaer and Toint for the approximate solution of the subproblems requires explicit knowledge of derivatives. Such information is presumed absent in the generating set search method we employ. Instead, we show that stationarity results for linearly constrained generating set search methods provide a derivative-free stopping criterion, based on a step-length control parameter, that is sufficient to preserve the convergence properties of the original augmented Lagrangian algorithm.

  9. [Public financing of health care in Africa, budgetary constraints and direct payment by users: an overview of the essential questions].

    PubMed

    Mathonnat, Jacky

    2008-12-01

    The improvement of health in Africa is confronted with many challenges. The financial resources devoted to health are insufficient, but to increase them is not enough. It is essential to reinforce the systems of health care and to improve efficiency of the public and private expenditure in health. In the majority of the countries, the budgetary constraints are strong, but there is room for maneuver to increase the public health expenditure, by domestic financing or by foreign assistance. It is advisable, however, to be particularly vigilant as to the negative effects which could possibly result from this on the various elements which might play a significant role in the improvement of health. States must exploit relevantly all possibilities of increasing the health expenditure which become available. A majority of them are not able to afford to neglect direct payments, even although they have to be integrated into a coherent strategy of financing, carefully analyzed and implemented.

  10. Directional genomic hybridization for chromosomal inversion discovery and detection.

    PubMed

    Ray, F Andrew; Zimmerman, Erin; Robinson, Bruce; Cornforth, Michael N; Bedford, Joel S; Goodwin, Edwin H; Bailey, Susan M

    2013-04-01

    Chromosomal rearrangements are a source of structural variation within the genome that figure prominently in human disease, where the importance of translocations and deletions is well recognized. In principle, inversions-reversals in the orientation of DNA sequences within a chromosome-should have similar detrimental potential. However, the study of inversions has been hampered by traditional approaches used for their detection, which are not particularly robust. Even with significant advances in whole genome approaches, changes in the absolute orientation of DNA remain difficult to detect routinely. Consequently, our understanding of inversions is still surprisingly limited, as is our appreciation for their frequency and involvement in human disease. Here, we introduce the directional genomic hybridization methodology of chromatid painting-a whole new way of looking at structural features of the genome-that can be employed with high resolution on a cell-by-cell basis, and demonstrate its basic capabilities for genome-wide discovery and targeted detection of inversions. Bioinformatics enabled development of sequence- and strand-specific directional probe sets, which when coupled with single-stranded hybridization, greatly improved the resolution and ease of inversion detection. We highlight examples of the far-ranging applicability of this cytogenomics-based approach, which include confirmation of the alignment of the human genome database and evidence that individuals themselves share similar sequence directionality, as well as use in comparative and evolutionary studies for any species whose genome has been sequenced. In addition to applications related to basic mechanistic studies, the information obtainable with strand-specific hybridization strategies may ultimately enable novel gene discovery, thereby benefitting the diagnosis and treatment of a variety of human disease states and disorders including cancer, autism, and idiopathic infertility.

  11. Direct Real-Time Detection of Vapors from Explosive Compounds

    SciTech Connect

    Ewing, Robert G.; Clowers, Brian H.; Atkinson, David A.

    2013-10-03

    The real-time detection of vapors from low volatility explosives including PETN, tetryl, RDX and nitroglycerine along with various compositions containing these substances is demonstrated. This was accomplished with an atmospheric flow tube (AFT) using a non-radioactive ionization source and coupled to a mass spectrometer. Direct vapor detection was demonstrated in less than 5 seconds at ambient temperature without sample pre-concentration. The several seconds of residence time of analytes in the AFT provides a significant opportunity for reactant ions to interact with analyte vapors to achieve ionization. This extended reaction time, combined with the selective ionization using the nitrate reactant ions (NO3- and NO3-•HNO3), enables highly sensitive explosives detection. Observed signals from diluted explosive vapors indicate detection limits below 10 ppqv using selected ion monitoring (SIM) of the explosive-nitrate adduct at m/z 349, 378, 284 and 289 for tetryl, PETN, RDX and NG respectively. Also provided is a demonstration of the vapor detection from 10 different energetic formulations, including double base propellants, plastic explosives and commercial blasting explosives using SIM for the NG, PETN and RDX product ions.

  12. Direct Imaging Detectability of Tidally Heated ExoMoons (THEM)

    NASA Astrophysics Data System (ADS)

    Turner, Edwin L.; Peters, Mary Anne

    2013-07-01

    Existing and planned ground and space based telescopes are capable of directly imaging plausible tidally heated exomoons orbiting gas-giant exoplanets. Tidally heated exomoons can plausibly be far more luminous than their host exoplanet and as much as 0.001 as bright as the system's stellar primary. Because emission from exomoons can be powered by tidal forces, their luminosities are independent of their separations from the system's stellar primary. Furthermore, high surface temperatures can occur in systems that are billions of years old. Tidally heated exomoons may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected separation (typically at least tens of AU) from their primary to be accessible to direct imaging currently. For example, the (warm) Spitzer Space Telescope and the next generation of ground based instruments could detect an exomoon roughly the size of the Earth at a temperature of ~600 K and a distance ~5 parsecs in IR bands; in more favorable cases, detections are possible at distances of tens of parsecs. Future mid-infrared space telescopes, such as JWST and SPICA, will be capable of directly imaging tidally heated exomoons around the nearest two dozen stars with brightness temperatures of ~300 K and sizes similar to the Earth orbiting beyond 10 AU at a 5 sigma confidence level in a 10^4 second integration. If such exomoons exist and are sufficiently common (and thus nearby), it may be easier to directly image an exomoon with surface conditions that allow the existence of liquid water than it will be to resolve an Earth-like planet in the classical Habitable Zone from its primary.

  13. Auditory feature detection for stimuli presented from different directions

    NASA Astrophysics Data System (ADS)

    Bronkhorst, Adelbert W.; Townsend, James T.

    2002-05-01

    The processing of stimulus features by the visual system is commonly studied by measuring response times (RTs) for detection of targets presented with a varying number of distracters. In audition, however, interpretation of the interaction between target and distracters is complicated by effects like masking, binaural gain and fusion. In the present paradigm, which uses stimuli presented from different directions in the horizontal plane, these confounding effects were either minimized or kept constant. Targets were synthetic vowels and RTs were measured for detection of three features: F0, spectrum (type of vowel) and direction. Both single features and conjunctions were studied. Independent variables were the type of distracters (synthetic vowels or spectrally shaped noise) and their number. Results show that the effect of the number of distracters on the RT is smallest for the spectrum feature; RTs for the detection of F0 are largest and vary considerably across subjects. For conjunctions of features, the RTs lie, as expected, between the RTs for the single features. The effect of the type of distracter on the RT is small-this indicates that the processing involved in segregating vowels from noise is not more efficient than that used for segregating vowels from other vowels.

  14. Monthly modulation in dark matter direct-detection experiments

    SciTech Connect

    Britto, Vivian; Meyers, Joel E-mail: jmeyers@cita.utoronto.ca

    2015-11-01

    The signals in dark matter direct-detection experiments should exhibit modulation signatures due to the Earth's motion with respect to the Galactic dark matter halo. The annual and daily modulations, due to the Earth's revolution about the Sun and rotation about its own axis, have been explored previously. Monthly modulation is another such feature present in direct detection signals, and provides a nearly model-independent method of distinguishing dark matter signal events from background. We study here monthly modulations in detail for both WIMP and WISP dark matter searches, examining both the effect of the motion of the Earth about the Earth-Moon barycenter and the gravitational focusing due to the Moon. For WIMP searches, we calculate the monthly modulation of the count rate and show the effects are too small to be observed in the foreseeable future. For WISP dark matter experiments, we show that the photons generated by WISP to photon conversion have frequencies which undergo a monthly modulating shift which is detectable with current technology and which cannot in general be neglected in high resolution WISP searches.

  15. Clustering and community detection in directed networks: A survey

    NASA Astrophysics Data System (ADS)

    Malliaros, Fragkiskos D.; Vazirgiannis, Michalis

    2013-12-01

    Networks (or graphs) appear as dominant structures in diverse domains, including sociology, biology, neuroscience and computer science. In most of the aforementioned cases graphs are directed - in the sense that there is directionality on the edges, making the semantics of the edges nonsymmetric as the source node transmits some property to the target one but not vice versa. An interesting feature that real networks present is the clustering or community structure property, under which the graph topology is organized into modules commonly called communities or clusters. The essence here is that nodes of the same community are highly similar while on the contrary, nodes across communities present low similarity. Revealing the underlying community structure of directed complex networks has become a crucial and interdisciplinary topic with a plethora of relevant application domains. Therefore, naturally there is a recent wealth of research production in the area of mining directed graphs - with clustering being the primary method sought and the primary tool for community detection and evaluation. The goal of this paper is to offer an in-depth comparative review of the methods presented so far for clustering directed networks along with the relevant necessary methodological background and also related applications. The survey commences by offering a concise review of the fundamental concepts and methodological base on which graph clustering algorithms capitalize on. Then we present the relevant work along two orthogonal classifications. The first one is mostly concerned with the methodological principles of the clustering algorithms, while the second one approaches the methods from the viewpoint regarding the properties of a good cluster in a directed network. Further, we present methods and metrics for evaluating graph clustering results, demonstrate interesting application domains and provide promising future research directions.

  16. Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength.

    PubMed

    Wakui, Kentaro; Eto, Yujiro; Benichi, Hugo; Izumi, Shuro; Yanagida, Tetsufumi; Ema, Kazuhiro; Numata, Takayuki; Fukuda, Daiji; Takeoka, Masahiro; Sasaki, Masahide

    2014-01-01

    Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology. PMID:24694515

  17. Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength

    PubMed Central

    Wakui, Kentaro; Eto, Yujiro; Benichi, Hugo; Izumi, Shuro; Yanagida, Tetsufumi; Ema, Kazuhiro; Numata, Takayuki; Fukuda, Daiji; Takeoka, Masahiro; Sasaki, Masahide

    2014-01-01

    Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology. PMID:24694515

  18. Optical filtering in directly modulated/detected OOFDM systems.

    PubMed

    Sánchez, C; Ortega, B; Wei, J L; Capmany, J

    2013-12-16

    This work presents a theoretical investigation on the performance of directly modulated/detected (DM/DD) optical orthogonal frequency division multiplexed (OOFDM) systems subject to optical filtering. The impact of both linear and nonlinear distortion effects are taken into account to calculate the effective signal-to-noise ratio of each subcarrier. These results are then employed to optimize the design parameters of two simple optical filtering structures: a Mach Zehnder interferometer and a uniform fiber Bragg grating, leading to a significant optical power budget improvement given by 3.3 and 3dB, respectively. These can be further increased to 5.5 and 4.2dB respectively when balanced detection configurations are employed. We find as well that this improvement is highly dependent on the clipping ratio. PMID:24514636

  19. Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength.

    PubMed

    Wakui, Kentaro; Eto, Yujiro; Benichi, Hugo; Izumi, Shuro; Yanagida, Tetsufumi; Ema, Kazuhiro; Numata, Takayuki; Fukuda, Daiji; Takeoka, Masahiro; Sasaki, Masahide

    2014-01-01

    Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology.

  20. Detecting tubular structures via direct vector field singularity characterization.

    PubMed

    Cabuk, Aytekin D; Alpay, Erdenay; Acar, Burak

    2010-01-01

    The initial step of vessel segmentation in 3D is the detection of vessel centerlines. The proposed methods in literature are either dependent on vessel radius and/or have low response at vessel bifurcations. In this paper we propose a 3D tubular structure detection method that removes these two drawbacks. The proposed method exploits the observations on the eigenvalues of the Hessian matrix as is done in literature, yet it employs a direct 3D vector field singularity characterization. The Gradient Vector Flow vector field is used and the eigenvalues of its Jacobian are exploited in computing a parameter free vesselness map. Results on phantom and real patient data exhibit robustness to scale, high response at vessel bifurcations, and good noise/non-vessel structure suppression.

  1. New archaeomagnetic direction results from China and their constraints on palaeosecular variation of the geomagnetic field in Eastern Asia

    NASA Astrophysics Data System (ADS)

    Cai, Shuhui; Tauxe, Lisa; Deng, Chenglong; Qin, Huafeng; Pan, Yongxin; Jin, Guiyun; Chen, Xuexiang; Chen, Wei; Xie, Fei; Zhu, Rixiang

    2016-11-01

    We carried out an archaeomagnetic directional study on 38 oriented samples (bricks and baked clays) collected from four archaeological locations at three provinces in China. The ages of our samples, spanning from ˜3000 BCE to ˜1300 CE, were constrained using a combination of archaeological context, radiocarbon dating and stratigraphic information. Rock magnetic results demonstrate that the main magnetic minerals of the studied samples are magnetite and/or hematite in single domain and superparamagnetic states. A total of 20 new reliable archaeodirectional data from 12 independent sites are obtained after thermal demagnetization experiments. These are the first set of archaeodirectional data in China produced since the 1990s. The published data are largely from the past 2 kyr and data from older time periods are rare. Our new data, especially those from period older than 3 ka, fill many gaps of the presently published dataset and will provide strong constraints on palaeosecular variation of the geomagnetic field in Eastern Asia and on the improvement of global models. Quite a few inflection points in the direction of the geomagnetic field are recorded in Eastern Asia over the past 10 kyr and some of them synchronize with the maximums or minimums of the palaeointensity. The palaeosecular variation rates are very low (based on present data distribution) before 2000 BCE and then start to increase and fluctuate afterward, which is generally consistent with the pattern of palaeointensity variations in this area.

  2. New archaeomagnetic direction results from China and their constraints on paleosecular variation of the geomagnetic field in Eastern Asia

    NASA Astrophysics Data System (ADS)

    Cai, Shuhui; Tauxe, Lisa; Deng, Chenglong; Qin, Huafeng; Pan, Yongxin; Jin, Guiyun; Chen, Xuexiang; Chen, Wei; Xie, Fei; Zhu, Rixiang

    2016-09-01

    We carried out an archaeomagnetic directional study on 38 oriented samples (bricks and baked clays) collected from four archaeological locations at three provinces in China. The ages of our samples, spanning from ˜3000 BCE to ˜1300 CE, were constrained using a combination of archaeological context, radiocarbon dating and stratigraphic information. Rock magnetic results demonstrate that the main magnetic minerals of the studied samples are magnetite and/or hematite in single domain and superparamagnetic states. A total of 20 new reliable archaeodirectional data from 12 independent sites are obtained after thermal demagnetization experiments. These are the first set of archaeodirectional data in China produced since the 1990 s. The published data are largely from the past 2 kyr and data from older time periods are rare. Our new data, especially those from period older than 3 ka, fill many gaps of the presently published dataset and will provide strong constraints on paleosecular variation of the geomagnetic field in Eastern Asia and on the improvement of global models. Quite a few inflection points in the direction of the geomagnetic field are recorded in Eastern Asia over the past 10 kyr and some of them synchronize with the maximums or minimums of the paleointensity. The paleosecular variation rates are very low (based on present data distribution) before 2000 BCE and then start to increase and fluctuate afterward, which is generally consistent with the pattern of paleointensity variations in this area.

  3. Constraining the initial entropy of directly detected exoplanets

    NASA Astrophysics Data System (ADS)

    Marleau, G.-D.; Cumming, A.

    2014-01-01

    The post-formation, initial entropy Si of a gas giant planet is a key witness to its mass-assembly history and a crucial quantity for its early evolution. However, formation models are not yet able to predict reliably Si, making unjustified the use solely of traditional, `hot-start' cooling tracks to interpret direct-imaging results and calling for an observational determination of initial entropies to guide formation scenarios. Using a grid of models in mass and entropy, we show how to place joint constraints on the mass and initial entropy of an object from its observed luminosity and age. This generalizes the usual estimate of only a lower bound on the real mass, through hot-start tracks. Moreover, we demonstrate that with mass information, e.g. from dynamical-stability analyses or radial velocity, tighter bounds can be set on the initial entropy. We apply this procedure to 2M1207 b and find that its initial entropy is at least 9.2 kB/baryon, assuming that it does not burn deuterium. For the planets of the HR 8799 system, we infer that they must have formed with Si > 9.2 kB/baryon, independent of uncertainties about the age of the star. Finally, a similar analysis for β Pic b reveals that it must have formed with Si > 10.5 kB/baryon, using the radial-velocity mass upper limit. These initial entropy values are, respectively, ca. 0.7, 0.5 and 1.5 kB/baryon higher than the ones obtained from core-accretion models by Marley et al., thereby quantitatively ruling out the coldest starts for these objects and constraining warm starts, especially for β Pic b.

  4. Constraints on the luminosity function of gamma-ray bursts detected by BATSE

    NASA Technical Reports Server (NTRS)

    Horack, J. M.; Emslie, A. G.; Meegan, C. A.

    1994-01-01

    We have utilized the integral moment analysis technique of Horack & Emslie to extract information on the allowable form of the luminosity function for gamma-ray bursts observed by Burst and Transient Source Experiment (BATSE). Using the general properties of moments, we are able to derive constraints on the range of luminosity from which the gamma-ray bursts must be sampled. These constraints are independent of the form of the radial distribution of the gamma-ray bursts, and depend only on the assumptions that space is Euclidean and that the luminosity function phi(L) is distance independent. For power-law luminosity functions of the form phi(L) = A(sub 0)L(exp -alpha), we find that the range of luminosity from which 80% of the gamma-ray bursts must be sampled cannot exceed approximately 6.5, with a 3 sigma upper limit of 12-15, regardless of the value of alpha.

  5. Direct detection of the 229Th nuclear clock transition

    NASA Astrophysics Data System (ADS)

    von der Wense, Lars; Seiferle, Benedict; Laatiaoui, Mustapha; Neumayr, Jürgen B.; Maier, Hans-Jörg; Wirth, Hans-Friedrich; Mokry, Christoph; Runke, Jörg; Eberhardt, Klaus; Düllmann, Christoph E.; Trautmann, Norbert G.; Thirolf, Peter G.

    2016-05-01

    Today’s most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of 229Th (denoted 229mTh). Here we report the direct detection of this nuclear state, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters. On the basis of this direct detection, the isomeric energy is constrained to between 6.3 and 18.3 electronvolts, and the half-life is found to be longer than 60 seconds for 229mTh2+. More precise determinations appear to be within reach, and would pave the way to the development of a nuclear frequency standard.

  6. Directional detection of dark matter in universal bound states

    DOE PAGESBeta

    Laha, Ranjan

    2015-10-06

    It has been suggested that several small-scale structure anomalies in Λ CDM cosmology can be solved by strong self-interaction between dark matter particles. It was shown in Ref. [1] that the presence of a near threshold S-wave resonance can make the scattering cross section at nonrelativistic speeds come close to saturating the unitarity bound. This can result in the formation of a stable bound state of two asymmetric dark matter particles (which we call darkonium). Ref. [2] studied the nuclear recoil energy spectrum in dark matter direct detection experiments due to this incident bound state. Here we study the angularmore » recoil spectrum, and show that it is uniquely determined up to normalization by the S-wave scattering length. Furthermore, observing this angular recoil spectrum in a dark matter directional detection experiment will uniquely determine many of the low-energy properties of dark matter independent of the underlying dark matter microphysics.« less

  7. Direct detection of the (229)Th nuclear clock transition.

    PubMed

    von der Wense, Lars; Seiferle, Benedict; Laatiaoui, Mustapha; Neumayr, Jürgen B; Maier, Hans-Jörg; Wirth, Hans-Friedrich; Mokry, Christoph; Runke, Jörg; Eberhardt, Klaus; Düllmann, Christoph E; Trautmann, Norbert G; Thirolf, Peter G

    2016-05-01

    Today's most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of (229)Th (denoted (229m)Th). Here we report the direct detection of this nuclear state, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters. On the basis of this direct detection, the isomeric energy is constrained to between 6.3 and 18.3 electronvolts, and the half-life is found to be longer than 60 seconds for (229m)Th(2+). More precise determinations appear to be within reach, and would pave the way to the development of a nuclear frequency standard. PMID:27147026

  8. Direct detection of the (229)Th nuclear clock transition.

    PubMed

    von der Wense, Lars; Seiferle, Benedict; Laatiaoui, Mustapha; Neumayr, Jürgen B; Maier, Hans-Jörg; Wirth, Hans-Friedrich; Mokry, Christoph; Runke, Jörg; Eberhardt, Klaus; Düllmann, Christoph E; Trautmann, Norbert G; Thirolf, Peter G

    2016-05-01

    Today's most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of (229)Th (denoted (229m)Th). Here we report the direct detection of this nuclear state, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters. On the basis of this direct detection, the isomeric energy is constrained to between 6.3 and 18.3 electronvolts, and the half-life is found to be longer than 60 seconds for (229m)Th(2+). More precise determinations appear to be within reach, and would pave the way to the development of a nuclear frequency standard.

  9. Understanding WIMP-baryon interactions with direct detection: a roadmap

    SciTech Connect

    Gluscevic, Vera; Peter, Annika H.G. E-mail: apeter@physics.osu.edu

    2014-09-01

    We study prospects of dark-matter direct-detection searches for probing non-relativistic effective theory for WIMP-baryon scattering. We simulate a large set of noisy recoil-energy spectra for different scattering scenarios (beyond the standard momentum-independent contact interaction), for Generation 2 and futuristic experiments. We analyze these simulations and quantify the probability of successfully identifying the operator governing the scattering, if a WIMP signal is observed. We find that the success rate depends on a combination of factors: the WIMP mass, the mediator mass, the type of interaction, and the experimental energy window. For example, for a 20 GeV WIMP, Generation 2 is only likely to identify the right operator if the interaction is Coulomb-like, and is unlikely to do so in any other case. For a WIMP with a mass of 200 GeV or higher, success is almost guaranteed. We also find that, regardless of the scattering model and the WIMP parameters, a single Generation 2 experiment is unlikely to successfully discern the momentum dependence of the underlying operator on its own, but prospects improve drastically when experiments with different target materials and energy windows are analyzed jointly. Furthermore, we examine the quality of parameter estimation and degeneracies in the multi-dimensional parameter space of the effective theory. We find in particular that the resulting WIMP mass estimates can be severely biased if data are analyzed assuming the standard (momentum-independent) operator while the actual operator has momentum-dependence. Finally, we evaluate the ultimate reach of direct detection, finding that the prospects for successful operator selection prior to reaching the irreducible backgrounds are excellent, if the signal is just below the current limits, but slim if Generation 2 does not report WIMP detection.

  10. Development of a novel gamma probe for detecting radiation direction

    NASA Astrophysics Data System (ADS)

    Pani, R.; Pellegrini, R.; Cinti, M. N.; Longo, M.; Donnarumma, R.; D'Alessio, A.; Borrazzo, C.; Pergola, A.; Ridolfi, S.; De Vincentis, G.

    2016-01-01

    Spatial localization of radioactive sources is currently a main issue interesting different fields, including nuclear industry, homeland security as well as medical imaging. It is currently achieved using different systems, but the development of technologies for detecting and characterizing radiation is becoming important especially in medical imaging. In this latter field, radiation detection probes have long been used to guide surgery, thanks to their ability to localize and quantify radiopharmaceutical uptake even deep in tissue. Radiolabelled colloid is injected into, or near to, the tumor and the surgeon uses a hand-held radiation detector, the gamma probe, to identify lymph nodes with radiopharmaceutical uptkake. The present work refers to a novel scintigraphic goniometric probe to identify gamma radiation and its direction. The probe incorporates several scintillation crystals joined together in a particular configuration to provide data related to the position of a gamma source. The main technical characteristics of the gamma locator prototype, i.e. sensitivity, spatial resolution and detection efficiency, are investigated. Moreover, the development of a specific procedure applied to the images permits to retrieve the source position with high precision with respect to the currently used gamma probes. The presented device shows a high sensitivity and efficiency to identify gamma radiation taking a short time (from 30 to 60 s). Even though it was designed for applications in radio-guided surgery, it could be used for other purposes, as for example homeland security.

  11. Isothermal Detection of Mycoplasma pneumoniae Directly from Respiratory Clinical Specimens

    PubMed Central

    Petrone, Brianna L.; Wolff, Bernard J.; DeLaney, Alexandra A.; Diaz, Maureen H.

    2015-01-01

    Mycoplasma pneumoniae is a leading cause of community-acquired pneumonia (CAP) across patient populations of all ages. We have developed a loop-mediated isothermal amplification (LAMP) assay that enables rapid, low-cost detection of M. pneumoniae from nucleic acid extracts and directly from various respiratory specimen types. The assay implements calcein to facilitate simple visual readout of positive results in approximately 1 h, making it ideal for use in primary care facilities and resource-poor settings. The analytical sensitivity of the assay was determined to be 100 fg by testing serial dilutions of target DNA ranging from 1 ng to 1 fg per reaction, and no cross-reactivity was observed against 17 other Mycoplasma species, 27 common respiratory agents, or human DNA. We demonstrated the utility of this assay by testing nucleic acid extracts (n = 252) and unextracted respiratory specimens (n = 72) collected during M. pneumoniae outbreaks and sporadic cases occurring in the United States from February 2010 to January 2014. The sensitivity of the LAMP assay was 88.5% tested on extracted nucleic acid and 82.1% evaluated on unextracted clinical specimens compared to a validated real-time PCR test. Further optimization and improvements to this method may lead to the availability of a rapid, cost-efficient laboratory test for M. pneumoniae detection that is more widely available to primary care facilities, ultimately facilitating prompt detection and appropriate responses to potential M. pneumoniae outbreaks and clusters within the community. PMID:26179304

  12. On the Existence of Low-Mass Dark Matter and its Direct Detection

    PubMed Central

    Bateman, James; McHardy, Ian; Merle, Alexander; Morris, Tim R.; Ulbricht, Hendrik

    2015-01-01

    Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too. PMID:25622565

  13. On the existence of low-mass dark matter and its direct detection.

    PubMed

    Bateman, James; McHardy, Ian; Merle, Alexander; Morris, Tim R; Ulbricht, Hendrik

    2015-01-27

    Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

  14. On the existence of low-mass dark matter and its direct detection.

    PubMed

    Bateman, James; McHardy, Ian; Merle, Alexander; Morris, Tim R; Ulbricht, Hendrik

    2015-01-01

    Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too. PMID:25622565

  15. On the Existence of Low-Mass Dark Matter and its Direct Detection

    NASA Astrophysics Data System (ADS)

    Bateman, James; McHardy, Ian; Merle, Alexander; Morris, Tim R.; Ulbricht, Hendrik

    2015-01-01

    Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

  16. Halo-independent direct detection analyses without mass assumptions

    SciTech Connect

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the m{sub χ}−σ{sub n} plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the v{sub min}−g-tilde plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from v{sub min} to nuclear recoil momentum (p{sub R}), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h-til-tilde(p{sub R}). The entire family of conventional halo-independent g-tilde(v{sub min}) plots for all DM masses are directly found from the single h-tilde(p{sub R}) plot through a simple rescaling of axes. By considering results in h-tilde(p{sub R}) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple g-tilde(v{sub min}) plots for different DM masses. We conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  17. Halo-independent direct detection analyses without mass assumptions

    DOE PAGESBeta

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ – σn plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the vmin – g~ plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from vmin to nuclear recoil momentum (pR),more » the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call tilde h(pR). The entire family of conventional halo-independent tilde g~(vmin) plots for all DM masses are directly found from the single tilde h~(pR) plot through a simple rescaling of axes. By considering results in tildeh~(pR) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple tilde g~(vmin) plots for different DM masses. As a result, we conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.« less

  18. Halo-independent direct detection analyses without mass assumptions

    SciTech Connect

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew E-mail: pjfox@fnal.gov E-mail: matthew.mccullough@cern.ch

    2015-10-01

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the m{sub χ}−σ{sub n} plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the v{sub min}− g-tilde plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from v{sub min} to nuclear recoil momentum (p{sub R}), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call h-tilde (p{sub R}). The entire family of conventional halo-independent g-tilde (v{sub min}) plots for all DM masses are directly found from the single h-tilde (p{sub R}) plot through a simple rescaling of axes. By considering results in h-tilde (p{sub R}) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple g-tilde (v{sub min}) plots for different DM masses. We conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  19. Halo-independent direct detection analyses without mass assumptions

    SciTech Connect

    Anderson, Adam J.; Fox, Patrick J.; Kahn, Yonatan; McCullough, Matthew

    2015-10-06

    Results from direct detection experiments are typically interpreted by employing an assumption about the dark matter velocity distribution, with results presented in the mχ – σn plane. Recently methods which are independent of the DM halo velocity distribution have been developed which present results in the vmin – g~ plane, but these in turn require an assumption on the dark matter mass. Here we present an extension of these halo-independent methods for dark matter direct detection which does not require a fiducial choice of the dark matter mass. With a change of variables from vmin to nuclear recoil momentum (pR), the full halo-independent content of an experimental result for any dark matter mass can be condensed into a single plot as a function of a new halo integral variable, which we call tilde h(pR). The entire family of conventional halo-independent tilde g~(vmin) plots for all DM masses are directly found from the single tilde h~(pR) plot through a simple rescaling of axes. By considering results in tildeh~(pR) space, one can determine if two experiments are inconsistent for all masses and all physically possible halos, or for what range of dark matter masses the results are inconsistent for all halos, without the necessity of multiple tilde g~(vmin) plots for different DM masses. As a result, we conduct a sample analysis comparing the CDMS II Si events to the null results from LUX, XENON10, and SuperCDMS using our method and discuss how the results can be strengthened by imposing the physically reasonable requirement of a finite halo escape velocity.

  20. Tropospheric Wind Profile Measurements with a Direct Detection Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Li, Steven X.; Korb, C. Laurence; Chen, Huailin; Mathur, Savyasachee

    1998-01-01

    Research has established the importance of global tropospheric wind measurements for large scale improvements in numerical weather prediction. In addition, global wind measurements provide data that are fundamental to the understanding and prediction of global climate change. These tasks are closely linked with the goals of the NASA Earth Science Enterprise and Global Climate Change programs. NASA Goddard has been actively involved in the development of direct detection Doppler lidar methods and technologies to meet the wind observing needs of the atmospheric science community. In this paper we describe a recently developed prototype wind lidar system using a direct detection Doppler technique for measuring wind profiles from the surface through the troposphere. This system uses a pulsed ND:YAG laser operating at 1064 nm as the transmitter. The laser pulse is directed to the atmosphere using a 40 cm diameter scan mirror. The portion of the laser energy backscattered from aerosols and molecules is collected by a 40 cm diameter telescope and coupled via fiber optics into the Doppler receiver. Single photon counting APD's are used to detect the atmospheric backscattered signal. The principle element of the receiver is a dual bandpass tunable Fabry Perot etalon which analyzes the Doppler shift of the incoming laser signal using the double edge technique. The double edge technique uses two high resolution optical filters having bandpasses offset relative to one another such that the 'edge' of the first filter's transmission function crosses that of the second at the half power point. The outgoing laser frequency is located approximately at the crossover point. Due to the opposite going slopes of the edges, a Doppler shift in the atmospheric backscattered laser frequency produces a positive change in signal for one filter and a negative change in the second filter. Taking the ratio of the two edge channel signals yields a result which is directly proportional to the

  1. Direct Testing of Blood Cultures for Detection of Streptococcal Antigens

    PubMed Central

    Wetkowski, Maryellen A.; Peterson, Ellena M.; De La Maza, Luis M.

    1982-01-01

    A direct, rapid, and simple method for the detection of streptococcal antigens of Lancefield groups A, B, C, D, and G from blood cultures was developed by using a coagglutination test. Fifty-five clinical specimens and 117 simulated blood cultures containing gram-positive cocci were tested. Out of 6,261 clinical blood cultures screened, 55 cultures from 53 patients were positive, with organisms resembling streptococci, by Gram stain. Of these cultures, 78% (43 of 55) were pure cultures of streptococci, and 22% (12 of 55) were mixed with at least one other organism. Of the 43 pure cultures only, correct reactions were obtained (grouping correctly or giving no cross-reactions, or both) with 86% (37 of 43) of the isolates, 12% (5 of 43) exhibited cross-reactions, and 2% (1 of 43) gave false-negative reactions. All of the cross-reacting isolates were Streptococcus pneumoniae, which reacted with the group C reagent, and the false-negative reaction occurred with a Streptococcus bovis isolate. However, by using a direct modified bile solubility test, the correct identification of the S. pneumoniae isolates was obtained. Therefore, by using the modified bile solubility test in conjunction with the direct grouping method, 98% (42 of 43) of the isolates in pure culture could be identified accurately and rapidly after the detection of a positive Gram stain. Correct grouping reactions were obtained with 83% (10 of 12) of the mixed blood cultures, and false-negative results occurred with 17% (2 of 12) of them. Both cultures contained an enterococcus and a gram-negative rod. Of the 117 simulated blood cultures, there was only one incorrect grouping reaction; this occurred with an S. bovis isolate that cross-reacted with the group C reagent. The direct grouping reaction was positive when blood cultures contained a minimum of 1 × 108 to 8 × 108 colony-forming units per ml. In general, this procedure provided information on the identification of the organism 24 h earlier than by

  2. Direct-detection wind lidar operating with a multimode laser.

    PubMed

    Bruneau, Didier; Blouzon, Frédéric; Spatazza, Joseph; Montmessin, Franck; Pelon, Jacques; Faure, Benoît

    2013-07-10

    A direct-detection wind lidar that operates with a multimode laser has been developed and tested. The instrument exploits the light backscattered by particles using a Mach-Zehnder interferometer with an optical path difference matched to the free spectral range of the laser longitudinal modes. In addition to requiring no monomodal emission, the system requires no frequency locking between the interferometer and the laser. We report laboratory and atmospheric measurements that show that the lidar is capable of measuring the radial wind velocity with a systematic error lower than 1 ms(-1) and a random error lower than 2 ms(-1) for a signal-to-noise ratio of 100. The development is motivated by the possibility to probe wind with a compact system in planetary atmospheres.

  3. Implications of direct dark matter constraints for minimal supersymmetric standard model Higgs boson searches at the Tevatron.

    PubMed

    Carena, Marcela; Hooper, Dan; Skands, Peter

    2006-08-01

    In regions of large tanbeta and small mAlpha, searches for heavy neutral minimal supersymmetric standard model (MSSM) Higgs bosons at the Tevatron are promising. At the same time, rates in direct dark matter experiments, such as CDMS, are enhanced in the case of large tanbeta and small mAlpha. As a result, there is a natural interplay between the heavy, neutral Higgs searches at the Tevatron and the region of parameter space explored by CDMS. We show that if the lightest neutralino makes up the dark matter of our universe, current limits from CDMS strongly constrain the prospects of heavy, neutral MSSM Higgs discovery at the Tevatron unless |mu| greater or approximately 400 GeV. The limits of CDMS projected for 2007 will increase this constraint to |mu| greater or approximately 800 GeV. If CDMS does observe neutralinos in the near future, however, it will make the discovery of Higgs bosons at the Tevatron far more likely. PMID:17026093

  4. Measurements of direct CP violation and constraints on the CKM triangle in B → K*π decays

    SciTech Connect

    Wagner, Andrew Phillips

    2010-02-01

    We constrain the apex of the Cabibbo-Kobayashi-Maskawa unitarity triangle with measurements of B → K*π amplitudes from analyses of B0 → K+π-π0 and B0 → KSπ+π- decays. This constraint is consistent with the world average. The B0 → K+π-π0 decay mode is reconstructed from a sample of 454 million B0$\\bar{B}$ 0 events collected by the BABAR detector at SLAC. We measure direct CP violation in B0 → K*+π- decays at the level of 3σ when measurements from both B0 → K+π-π0 and B0 → KSπ+π- decays are combined.

  5. Assessing Astrophysical Uncertainties in Direct Detection with Galaxy Simulations

    NASA Astrophysics Data System (ADS)

    Sloane, Jonathan D.; Buckley, Matthew R.; Brooks, Alyson M.; Governato, Fabio

    2016-11-01

    We study the local dark matter velocity distribution in simulated Milky Way-mass galaxies, generated at high resolution with both dark matter and baryons. We find that the dark matter in the solar neighborhood is influenced appreciably by the inclusion of baryons, increasing the speed of dark matter particles compared to dark matter-only simulations. The gravitational potential due to the presence of a baryonic disk increases the amount of high velocity dark matter, resulting in velocity distributions that are more similar to the Maxwellian Standard Halo Model than predicted from dark matter-only simulations. Furthermore, the velocity structures present in baryonic simulations possess a greater diversity than expected from dark matter-only simulations. We show that the impact on the direct detection experiments LUX, DAMA/Libra, and CoGeNT using our simulated velocity distributions, and explore how resolution and halo mass within the Milky Way’s estimated mass range impact the results. A Maxwellian fit to the velocity distribution tends to overpredict the amount of dark matter in the high velocity tail, even with baryons, and thus leads to overly optimistic direct detection bounds on models that are dependent on this region of phase space for an experimental signal. Our work further demonstrates that it is critical to transform simulated velocity distributions to the lab frame of reference, due to the fact that velocity structure in the solar neighborhood appears when baryons are included. There is more velocity structure present when baryons are included than in dark matter-only simulations. Even when baryons are included, the importance of the velocity structure is not as apparent in the Galactic frame of reference as in the Earth frame.

  6. Indirect detection constraints on s- and t-channel simplified models of dark matter

    NASA Astrophysics Data System (ADS)

    Carpenter, Linda M.; Colburn, Russell; Goodman, Jessica; Linden, Tim

    2016-09-01

    Recent Fermi-LAT observations of dwarf spheroidal galaxies in the Milky Way have placed strong limits on the gamma-ray flux from dark matter annihilation. In order to produce the strongest limit on the dark matter annihilation cross section, the observations of each dwarf galaxy have typically been "stacked" in a joint-likelihood analysis, utilizing optical observations to constrain the dark matter density profile in each dwarf. These limits have typically been computed only for singular annihilation final states, such as b b ¯ or τ+τ- . In this paper, we generalize this approach by producing an independent joint-likelihood analysis to set constraints on models where the dark matter particle annihilates to multiple final-state fermions. We interpret these results in the context of the most popular simplified models, including those with s- and t-channel dark matter annihilation through scalar and vector mediators. We present our results as constraints on the minimum dark matter mass and the mediator sector parameters. Additionally, we compare our simplified model results to those of effective field theory contact interactions in the high-mass limit.

  7. Single molecule detection of direct, homologous, DNA/DNA pairing

    PubMed Central

    Danilowicz, C.; Lee, C. H.; Kim, K.; Hatch, K.; Coljee, V. W.; Kleckner, N.; Prentiss, M.

    2009-01-01

    Using a parallel single molecule magnetic tweezers assay we demonstrate homologous pairing of two double-stranded (ds) DNA molecules in the absence of proteins, divalent metal ions, crowding agents, or free DNA ends. Pairing is accurate and rapid under physiological conditions of temperature and monovalent salt, even at DNA molecule concentrations orders of magnitude below those found in vivo, and in the presence of a large excess of nonspecific competitor DNA. Crowding agents further increase the reaction rate. Pairing is readily detected between regions of homology of 5 kb or more. Detected pairs are stable against thermal forces and shear forces up to 10 pN. These results strongly suggest that direct recognition of homology between chemically intact B-DNA molecules should be possible in vivo. The robustness of the observed signal raises the possibility that pairing might even be the “default” option, limited to desired situations by specific features. Protein-independent homologous pairing of intact dsDNA has been predicted theoretically, but further studies are needed to determine whether existing theories fit sequence length, temperature, and salt dependencies described here. PMID:19903884

  8. Subcarrier multiplexing with dispersion reduction and direct detection

    DOEpatents

    Sargis, Paul D.; Haigh, Ronald E.; McCammon, Kent G.

    1997-01-01

    An SCM system for simultaneously reducing the concomitant problems of receiver complexity and dispersion penalty and without requiring the use of an expensive, high-bandwidth optical detector. The system provides both a dispersion reduction and a direct detection to the receiver, with microwave mixers and lithium niobate external modulators that produce sidebands that are only separated by a few gigahertz from a principal laser optical carrier. Digital data streams are independently impressed upon these sidebands for transmission over an ordinary single-mode fiber. Independent high-speed data streams are upconverted to microwave frequencies. These subcarriers are then combined with a microwave power combiner and amplified with a microwave amplifier. A solid-state 1550-nm laser carrier is modulated by the microwave subcarriers. An erbium-doped fiber amplifier (EDFA) is used just prior to long-distance transmission over ordinary single-mode fiber. The transmitted optical signal may then traverse multiple EDFAs to compensate for long-haul optical fiber losses prior to detection. At a receiving end, the optical signal is split into multiple paths. The subcarrier channels are optically pre-selected using a narrowband optical filter, such as a fiber Fabry-Perot (FFP) filter. An optical detector converts the selected optical signal into a baseband electrical data stream.

  9. Direct x-ray detection with conjugated polymer devices

    NASA Astrophysics Data System (ADS)

    Boroumand, F. A.; Zhu, M.; Dalton, A. B.; Keddie, J. L.; Sellin, P. J.; Gutierrez, J. J.

    2007-07-01

    The authors report the first direct detection of x-ray induced photocurrents in thick films (up to 20μm) of conjugated polymers. Schottky-based "sandwich" structures were fabricated from layers of either poly[1-methoxy-4-(2-ethylhexyloxy)-phenylenevinylene] (MEH-PPV) or poly(9,9-dioctylfluorene) (PFO) on indium tin oxide substrates using a top contact of aluminum. Good rectification was achieved from the Al-polymer contact, with a reverse bias leakage current density as low as 4nA/cm2 at an electric field strength of 25kV/cm. Irradiation with x-rays from a 50kV x-ray tube produced a linear increase in photocurrent over a dose rate range from 4to18mGy/s. The observed x-ray sensitivities of 240nC/mGy/cm3 for MEH-PPV and 480nC/mGy/cm3 for PFO structures are comparable to that reported for Si devices. A response time of <150ms to pulsed x-ray irradiation was measured with no evidence of long-lived current transients. Conjugated polymers offer the advantage of easy coatability over large areas and on curved surfaces. Their low average atomic number provides tissue-equivalent dosimetric response, with many potential applications including medical x-ray and synchrotron photon detection.

  10. Subcarrier multiplexing with dispersion reduction and direct detection

    DOEpatents

    Sargis, P.D.; Haigh, R.E.; McCammon, K.G.

    1997-01-21

    An SCM system is disclosed for simultaneously reducing the concomitant problems of receiver complexity and dispersion penalty and without requiring the use of an expensive, high-bandwidth optical detector. The system provides both a dispersion reduction and a direct detection to the receiver, with microwave mixers and lithium niobate external modulators that produce sidebands that are only separated by a few gigahertz from a principal laser optical carrier. Digital data streams are independently impressed upon these sidebands for transmission over an ordinary single-mode fiber. Independent high-speed data streams are upconverted to microwave frequencies. These subcarriers are then combined with a microwave power combiner and amplified with a microwave amplifier. A solid-state 1550-nm laser carrier is modulated by the microwave subcarriers. An erbium-doped fiber amplifier (EDFA) is used just prior to long-distance transmission over ordinary single-mode fiber. The transmitted optical signal may then traverse multiple EDFAs to compensate for long-haul optical fiber losses prior to detection. At a receiving end, the optical signal is split into multiple paths. The subcarrier channels are optically pre-selected using a narrowband optical filter, such as a fiber Fabry-Perot (FFP) filter. An optical detector converts the selected optical signal into a baseband electrical data stream. 2 figs.

  11. Lenslet array to further suppress starlight for direct exoplanet detection

    NASA Astrophysics Data System (ADS)

    Gong, Qian; McElwain, Michael; Shiri, Ron

    2016-07-01

    Direct imaging plays a key role in the detection and characterization of exoplanets orbiting within its host star's habitable zone. Many innovative ideas for starlight suppression and wavefront control have been proposed and developed over the past decade. However, several technological challenges still lie ahead to achieve the required contrast, including controlling the observatory pointing performance, fabricating occulting masks with tight optical tolerances, developing wavefront control algorithms, controlling stray light, advancing single photon detecting detectors, and integrated system-level issues. This paper explores how a lenslet array and pinhole mask may be implemented to further suppress uncorrected starlight that leaks through the occulting mask. An external occulter, or star shade, is simulated to demonstrate this concept, although this approach can be implemented for internal coronagraphs as well. We describe how to use simple relay optics to control the scene near the inner working angle and the level of the suppression expected. Furthermore, if the lenslet array is the input to an integral field spectrograph, as planned for the WFIRST mission, the spectral content of the exoplanet atmospheres can be obtained to determine if the observed planet is habitable and ultimately, if it is inhabited.

  12. Direct Detections of Young Stars in Nearby Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Ford, H. Alyson; Bregman, Joel N.

    2013-06-01

    Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-infrared dust emission. Such star formation has previously been difficult to directly detect, but using ultraviolet Hubble Space Telescope Wide Field Camera 3 imaging, we have identified individual young stars and star clusters in four nearby ellipticals. Ongoing star formation is detected in all galaxies, including three ellipticals that have previously exhibited potential signposts of star-forming conditions (NGC 4636, NGC 4697, and NGC 4374), as well as the typical "red and dead" NGC 3379. The current star formation in our closest targets, where we are most complete, is between 2.0 and 9.8 × 10-5 M ⊙ yr-1. The star formation history was roughly constant from 0.5 to 1.5 Gyr (at (3-5) × 10-4 M ⊙ yr-1), but decreased by a factor of several in the past 0.3 Gyr. Most star clusters have a mass between 102 and 104 M ⊙. The specific star formation rates of ~10-16 yr-1 (at the present day) or ~10-14 yr-1 (when averaging over the past Gyr) imply that a fraction 10-8 of the stellar mass is younger than 100 Myr and 10-5 is younger than 1 Gyr, quantifying the level of frosting of recent star formation over the otherwise passive stellar population. There is no obvious correlation between either the presence or spatial distribution of postulated star formation indicators and the star formation we detect. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 11583.

  13. DIRECT DETECTIONS OF YOUNG STARS IN NEARBY ELLIPTICAL GALAXIES

    SciTech Connect

    Ford, H. Alyson; Bregman, Joel N.

    2013-06-20

    Small amounts of star formation in elliptical galaxies are suggested by several results: surprisingly young ages from optical line indices, cooling X-ray gas, and mid-infrared dust emission. Such star formation has previously been difficult to directly detect, but using ultraviolet Hubble Space Telescope Wide Field Camera 3 imaging, we have identified individual young stars and star clusters in four nearby ellipticals. Ongoing star formation is detected in all galaxies, including three ellipticals that have previously exhibited potential signposts of star-forming conditions (NGC 4636, NGC 4697, and NGC 4374), as well as the typical ''red and dead'' NGC 3379. The current star formation in our closest targets, where we are most complete, is between 2.0 and 9.8 Multiplication-Sign 10{sup -5} M{sub Sun} yr{sup -1}. The star formation history was roughly constant from 0.5 to 1.5 Gyr (at (3-5) Multiplication-Sign 10{sup -4} M{sub Sun} yr{sup -1}), but decreased by a factor of several in the past 0.3 Gyr. Most star clusters have a mass between 10{sup 2} and 10{sup 4} M{sub Sun }. The specific star formation rates of {approx}10{sup -16} yr{sup -1} (at the present day) or {approx}10{sup -14} yr{sup -1} (when averaging over the past Gyr) imply that a fraction 10{sup -8} of the stellar mass is younger than 100 Myr and 10{sup -5} is younger than 1 Gyr, quantifying the level of frosting of recent star formation over the otherwise passive stellar population. There is no obvious correlation between either the presence or spatial distribution of postulated star formation indicators and the star formation we detect.

  14. Direct and Indirect Dark Matter Detection in Gauge Theories

    SciTech Connect

    Queiroz, Farinaldo

    2013-01-01

    The Dark matter (DM) problem constitutes a key question at the interface among Particle Physics, Astrophysics and Cosmology. The observational data which have been accumulated in the last years point to an existence of non baryonic amount of DM. Since the Standard Model (SM) does not provide any candidate for such non-baryonic DM, the evidence of DM is a major indication for new physics beyond the SM. We will study in this work one of the most popular DM candidates, the so called WIMPs (Weakly Interacting Massive Particles) from a direct and indirect detection perspective. In order to approach the direct and indirect dection of DM in the context of Particle Physics in a more pedagogic way, we will begin our discussion talking about a minimal extension of the SM. Later we will work on the subject in a 3-3-1 model. Next, we will study the role of WIMPs in the Big Bang Nucleosynthesis. Lastly, we will look for indirect DM signals in the center of our galaxy using the NASA Satellite, called Fermi-LAT. Through a comprehensive analysis of the data events observed by Fermi-LAT and some background models, we will constrain the dark matter annihilation cross section for several annihilation channels and dark matter halo profiles.

  15. The intermediate size direct detection detector for electron microscopy

    NASA Astrophysics Data System (ADS)

    Jin, Liang; Milazzo, Anna-Clare; Kleinfelder, Stuart; Li, Shengdong; Leblanc, Philippe; Duttweiler, Fred; Bouwer, James C.; Peltier, Steve T.; Ellisman, Mark; Xuong, Nguyen-Huu

    2007-02-01

    In a longstanding effort to overcome limits of film and the charge coupled device (CCD) systems in electron microscopy, we have developed a radiation-tolerant system that can withstand direct electron bombardment. A prototype Direct Detection Device (DDD) detector based on an Active Pixel Sensor (APS) has delivered unprecedented performance with an excellent signal-to-noise ratio (approximately 5/1 for a single incident electron in the range of 200-400 keV) and a very high spatial resolution. This intermediate size prototype features a 512×550 pixel format of 5μm pitch. The detector response to uniform beam illumination and to single electron hits is reported. Radiation tolerance with high-energy electron exposure is also impressive, especially with cooling to -15 °C. Stable performance has been demonstrated, even after a total dose of 3.3×10 6 electrons/pixel. The characteristics of this new detector have exciting implications for transmission electron microscopy, especially for cryo-EM as applied to biological macromolecules.

  16. Direct Sequence Detection of Structured H5 Influenza Viral RNA

    PubMed Central

    Kerby, Matthew B.; Freeman, Sarah; Prachanronarong, Kristina; Artenstein, Andrew W.; Opal, Steven M.; Tripathi, Anubhav

    2008-01-01

    We describe the development of sequence-specific molecular beacons (dual-labeled DNA probes) for identification of the H5 influenza subtype, cleavage motif, and receptor specificity when hybridized directly with in vitro transcribed viral RNA (vRNA). The cloned hemagglutinin segment from a highly pathogenic H5N1 strain, A/Hanoi/30408/2005(H5N1), isolated from humans was used as template for in vitro transcription of sense-strand vRNA. The hybridization behavior of vRNA and a conserved subtype probe was characterized experimentally by varying conditions of time, temperature, and Mg2+ to optimize detection. Comparison of the hybridization rates of probe to DNA and RNA targets indicates that conformational switching of influenza RNA structure is a rate-limiting step and that the secondary structure of vRNA dominates the binding kinetics. The sensitivity and specificity of probe recognition of other H5 strains was calculated from sequence matches to the National Center for Biotechnology Information influenza database. The hybridization specificity of the subtype probes was experimentally verified with point mutations within the probe loop at five locations corresponding to the other human H5 strains. The abundance frequencies of the hemagglutinin cleavage motif and sialic acid recognition sequences were experimentally tested for H5 in all host viral species. Although the detection assay must be coupled with isothermal amplification on the chip, the new probes form the basis of a portable point-of-care diagnostic device for influenza subtyping. PMID:18403607

  17. A direction detective asymmetrical twin-core fiber curving sensor

    NASA Astrophysics Data System (ADS)

    An, Maowei; Geng, Tao; Yang, Wenlei; Zeng, Hongyi; Li, Jian

    2015-10-01

    Long period fiber gratings (LPFGs), which can couple the core mode to the forward propagating cladding modes of a fiber and have the advantage of small additional loss, no backward reflection, small size, which is widely used in optical fiber sensors and optical communication systems. LPFG has different fabricating methods, in order to write gratings on the twin-core at the same time effectively, we specially choose electric heating fused taper system to fabricate asymmetric dual-core long period fiber grating, because this kind of method can guarantee the similarity of gratings on the twin cores and obtain good geometric parameters of LPFG, such as cycle, cone waist. Then we use bending test platform to conduct bending test for each of the core of twin-core asymmetric long period fiber grating. Experiments show that: the sensitivity of asymmetrical twin-core long period fiber grating's central core under bending is -5.47nm·m, while the sensitivity of asymmetric twin-core long period fiber grating partial core changed with the relative position of screw micrometer. The sensitivity at 0°, 30°, 90° direction is -4.22nm·m, -9.84nm·m, -11.44nm·m respectively. The experiment results strongly demonstrate the properties of rim sensing of asymmetrical twin-core fiber gratings which provides the possibility of simultaneously measuring the bending magnitude and direction and solving the problem of cross sensing when multi-parameter measuring. In other words, we can detect temperature and bend at the same time by this sensor. As our knowledge, it is the first time simultaneously measuring bend and temperature using this structure of fiber sensors.

  18. GEOCHEMICAL AND ISOTOPIC CONSTRAINTS ON GROUND-WATER FLOW DIRECTIONS, MIXING AND RECHARGE AT YUCCA MOUNTAIN, NEVADA

    SciTech Connect

    A. Meijer; E. Kwicklis

    2000-08-17

    This analysis is governed by the Office of Civilian Radioactive Waste Management (OCRWM) Analysis and Modeling Report Development Plan entitled ''Geochemical and Isotopic Constraints on Groundwater Flow Directions, Mixing and Recharge at Yucca Mountain'' (CRWMS M&O 1999a). As stated in this Development Plan, the purpose of the work is to provide an analysis of groundwater recharge rates, flow directions and velocities, and mixing proportions of water from different source areas based on groundwater geochemical and isotopic data. The analysis of hydrochemical and isotopic data is intended to provide a basis for evaluating the hydrologic system at Yucca Mountain independently of analyses based purely on hydraulic arguments. Where more than one conceptual model for flow is possible, based on existing hydraulic data, hydrochemical and isotopic data may be useful in eliminating some of these conceptual models. This report documents the use of geochemical and isotopic data to constrain rates and directions of groundwater flow near Yucca Mountain and the timing and magnitude of recharge in the Yucca Mountain vicinity. The geochemical and isotopic data are also examined with regard to the possible dilution of groundwater recharge from Yucca Mountain by mixing with groundwater downgradient from the potential repository site. Specifically, the primary tasks of this report, as listed in the AMR Development Plan (CRWMS M&O 1999a), consist of the following: (1) Compare geochemical and isotopic data for perched and pore water in the unsaturated zone with similar data from the saturated zone to determine if local recharge is present in the regional groundwater system; (2) Determine the timing of the recharge from stable isotopes such as deuterium ({sup 2}H) and oxygen-18 ({sup 18}O), which are known to vary over time as a function of climate, and from radioisotopes such as carbon-14 ({sup 14}C) and chlorine-36 ({sup 36}Cl); (3) Determine the magnitude of recharge from relatively

  19. Direct detection of light ''Ge-phobic'' exothermic dark matter

    SciTech Connect

    Gelmini, Graciela B.; Georgescu, Andreea; Huh, Ji-Haeng E-mail: a.georgescu@physics.ucla.edu

    2014-07-01

    We present comparisons of direct dark matter (DM) detection data for light WIMPs with exothermic scattering with nuclei (exoDM), both assuming the Standard Halo Model (SHM) and in a halo model–independent manner. Exothermic interactions favor light targets, thus reducing the importance of upper limits derived from xenon targets, the most restrictive of which is at present the LUX limit. In our SHM analysis the CDMS-II-Si and CoGeNT regions become allowed by these bounds, however the recent SuperCDMS limit rejects both regions for exoDM with isospin-conserving couplings. An isospin-violating coupling of the exoDM, in particular one with a neutron to proton coupling ratio of -0.8 (which we call ''Ge-phobic''), maximally reduces the DM coupling to germanium and allows the CDMS-II-Si region to become compatible with all bounds. This is also clearly shown in our halo-independent analysis.

  20. Direct detection of exothermic dark matter with light mediator

    NASA Astrophysics Data System (ADS)

    Geng, Chao-Qiang; Huang, Da; Lee, Chun-Hao; Wang, Qing

    2016-08-01

    We study the dark matter (DM) direct detection for the models with the effects of the isospin-violating couplings, exothermic scatterings, and/or the lightness of the mediator, proposed to relax the tension between the CDMS-Si signals and null experiments. In the light of the new updates of the LUX and CDMSlite data, we find that many of the previous proposals are now ruled out, including the Ge-phobic exothermic DM model and the Xe-phobic DM one with a light mediator. We also examine the exothermic DM models with a light mediator but without the isospin violation, and we are unable to identify any available parameter space that could simultaneously satisfy all the experiments. The only models that can partially relax the inconsistencies are the Xe-phobic exothermic DM models with or without a light mediator. But even in this case, a large portion of the CDMS-Si regions of interest has been constrained by the LUX and SuperCDMS data.

  1. The effective field theory of dark matter direct detection

    SciTech Connect

    Fitzpatrick, A. Liam; Katz, Emanuel; Haxton, Wick; Lubbers, Nicholas; Xu, Yiming E-mail: haxton@berkeley.edu E-mail: nlubbers@bu.edu

    2013-02-01

    We extend and explore the general non-relativistic effective theory of dark matter (DM) direct detection. We describe the basic non-relativistic building blocks of operators and discuss their symmetry properties, writing down all Galilean-invariant operators up to quadratic order in momentum transfer arising from exchange of particles of spin 1 or less. Any DM particle theory can be translated into the coefficients of an effective operator and any effective operator can be simply related to most general description of the nuclear response. We find several operators which lead to novel nuclear responses. These responses differ significantly from the standard minimal WIMP cases in their relative coupling strengths to various elements, changing how the results from different experiments should be compared against each other. Response functions are evaluated for common DM targets — F, Na, Ge, I, and Xe — using standard shell model techniques. We point out that each of the nuclear responses is familiar from past studies of semi-leptonic electroweak interactions, and thus potentially testable in weak interaction studies. We provide tables of the full set of required matrix elements at finite momentum transfer for a range of common elements, making a careful and fully model-independent analysis possible. Finally, we discuss embedding non-relativistic effective theory operators into UV models of dark matter.

  2. Enabling Technologies for Direct Detection Optical Phase Modulation Formats

    NASA Astrophysics Data System (ADS)

    Xu, Xian

    Phase modulation formats are believed to be one of the key enabling techniques for next generation high speed long haul fiber-optic communication systems due to the following main advantages: (1) with a balanced detection, a better receiver sensitivity over conventional intensity modulation formats, e.g., a ˜3-dB sensitivity improvement using differential phase shift keying (DPSK) and a ˜1.3-dB sensitivity improvement using differential quadrature phase shift keying (DQPSK); (2) excellent robustness against fiber nonlinearities; (3) high spectrum efficiency when using multilevel phase modulation formats, such as DQPSK. As the information is encoded in the phase of the optical field, the phase modulation formats are sensitive to the phase-related impairments and the deterioration induced in the phase-intensity conversion. This consequently creates new challenging issues. The research objective of this thesis is to depict some of the challenging issues and provide possible solutions. The first challenge is the cross-phase modulation (XPM) penalty for the phase modulated channels co-propagating with the intensity modulated channels. The penalty comes from the pattern dependent intensity fluctuations of the neighboring intensity modulated channels being converted into phase noise in the phase modulation channels. We propose a model to theoretically analyze the XPM penalty dependence on the walk off effect. From this model, we suggest that using fibers with large local dispersion or intentionally introducing some residual dispersion per span would help mitigate the XPM penalty. The second challenge is the polarization dependent frequency shift (PDf) induced penalty during the phase-intensity conversion. The direct detection DPSK is usually demodulated in a Mach-Zehnder delay interferometer (DI). The polarization dependence of DI introduces a PDf causing a frequency offset between the laser's frequency and the transmissivity peak of DI, degrading the demodulated DPSK

  3. Dark matter protohalos in a nine parameter MSSM and implications for direct and indirect detection

    NASA Astrophysics Data System (ADS)

    Diamanti, Roberta; Catalan, Maria Eugenia Cabrera; Ando, Shin'ichiro

    2015-09-01

    We study how the kinetic decoupling of dark matter within a minimal supersymmetric extension of the standard model, by adopting nine independent parameters (MSSM-9), could improve our knowledge of the properties of the dark matter protohalos. We show that the most probable neutralino mass regions, which satisfy the relic density and the Higgs mass constraints, are those with the lightest supersymmetric neutralino mass around 1 TeV and 3 TeV, corresponding to Higgsino-like and winolike neutralino, respectively. The kinetic decoupling temperature in the MSSM-9 scenario leads to a most probable protohalo mass in a range of Mph˜10-12- 10-7M⊙ . The part of the region closer to ˜2 TeV gives also important contributions from the neutralino-stau coannihilation, reducing the effective annihilation rate in the early Universe. We also study how the size of the smallest dark matter substructures correlates to experimental signatures, such as the spin-dependent and spin-independent scattering cross sections, relevant for direct detection of dark matter. Improvements on the spin-independent sensitivity might reduce the most probable range of the protohalo mass between ˜10-9M⊙ and ˜10-7M⊙, while the expected spin-dependent sensitivity provides weaker constraints. We show how the boost of the luminosity due to dark matter annihilation increases, depending on the protohalo mass. In the Higgsino case, the protohalo mass is lower than the canonical value often used in the literature (˜10-6M⊙), while ⟨σ v ⟩ does not deviate from ⟨σ v ⟩˜10-26 cm3 s-1 ; there is no significant enhancement of the luminosity. On the contrary, in the wino case, the protohalo mass is even lighter, and ⟨σ v ⟩ is two orders of magnitude larger; as its consequence, we see a substantial enhancement of the luminosity.

  4. The Analysis of Optical, Direct Detection Communication Systems with Point Process Observations

    NASA Astrophysics Data System (ADS)

    Brady, David Paul

    1990-01-01

    The central theme of this work is the analysis of direct-detection optical communication channels based on point process observations. For example, we consider an optical DPSK receiver which is based on a binary hypothesis test with conditionally Poisson count observations. The error probability is influenced by the transmitting laser phase noise as well as the statistical nature of light, and decreases to the quantum limit as the transmitting laser linewidth vanishes. We bound the bit error rate by bounding the conditional photon arrival rates, and were shown to converge as the laser linewidth decreases. We also derive the exact error rate of a noncoherent, optical, asynchronous, CDMA system. The receiver utilizes fiber optic tap delay lines to create and correlate the signature sequence with the received point process, and compares an electron count to a threshold to decide for the data of the user of interest. The optical intensity on a surface illuminated by several phase-coherent signals is determined, and it is shown that the approximation of noncoherent addition in the fiber optic tap delay line is justified. The bit error rate is found for arbitrary photomultipliers and signature sequence sets, adheres fully to the semi-classical model of light, and does not depend on approximations for large user groups, strong received optical fields, or chip synchronism. The capacity of a direct-detection photon counting channel is addressed in this work. The limiting form of the capacity is found as the signal and noise energies increase proportionally, and it is shown that the capacity grows logarithmically with the signal energy constraint. When the noise energy increases polynomially with the signal energy, the limiting capacity coincides with that of a Gaussian channel with a positivity and variance constraint. Bounds on the capacity are considered for small and moderate energies by restricting attention to binary inputs. These bounds are arbitrarily tight, and are

  5. Bed bug detection: Current technologies and future directions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluates current technologies used to detect bed bug infestations, and presents new information regarding the underlying chemical basis of canines scent detection. The manuscript also reports new and future devices that may play a part in bed bug detection in the future....

  6. Identifying the theory of dark matter with direct detection

    SciTech Connect

    Gluscevic, Vera; Gresham, Moira I.; McDermott, Samuel D.; Peter, Annika H.G.; Zurek, Kathryn M.

    2015-12-29

    Identifying the true theory of dark matter depends crucially on accurately characterizing interactions of dark matter (DM) with other species. In the context of DM direct detection, we present a study of the prospects for correctly identifying the low-energy effective DM-nucleus scattering operators connected to UV-complete models of DM-quark interactions. We take a census of plausible UV-complete interaction models with different low-energy leading-order DM-nuclear responses. For each model (corresponding to different spin–, momentum–, and velocity-dependent responses), we create a large number of realizations of recoil-energy spectra, and use Bayesian methods to investigate the probability that experiments will be able to select the correct scattering model within a broad set of competing scattering hypotheses. We conclude that agnostic analysis of a strong signal (such as Generation-2 would see if cross sections are just below the current limits) seen on xenon and germanium experiments is likely to correctly identify momentum dependence of the dominant response, ruling out models with either “heavy” or “light” mediators, and enabling downselection of allowed models. However, a unique determination of the correct UV completion will critically depend on the availability of measurements from a wider variety of nuclear targets, including iodine or fluorine. We investigate how model-selection prospects depend on the energy window available for the analysis. In addition, we discuss accuracy of the DM particle mass determination under a wide variety of scattering models, and investigate impact of the specific types of particle-physics uncertainties on prospects for model selection.

  7. Identifying the theory of dark matter with direct detection

    SciTech Connect

    Gluscevic, Vera; Gresham, Moira I.; McDermott, Samuel D.; Peter, Annika H.G.; Zurek, Kathryn M. E-mail: gresham@whitman.edu E-mail: apeter@physics.osu.edu

    2015-12-01

    Identifying the true theory of dark matter depends crucially on accurately characterizing interactions of dark matter (DM) with other species. In the context of DM direct detection, we present a study of the prospects for correctly identifying the low-energy effective DM-nucleus scattering operators connected to UV-complete models of DM-quark interactions. We take a census of plausible UV-complete interaction models with different low-energy leading-order DM-nuclear responses. For each model (corresponding to different spin–, momentum–, and velocity-dependent responses), we create a large number of realizations of recoil-energy spectra, and use Bayesian methods to investigate the probability that experiments will be able to select the correct scattering model within a broad set of competing scattering hypotheses. We conclude that agnostic analysis of a strong signal (such as Generation-2 would see if cross sections are just below the current limits) seen on xenon and germanium experiments is likely to correctly identify momentum dependence of the dominant response, ruling out models with either 'heavy' or 'light' mediators, and enabling downselection of allowed models. However, a unique determination of the correct UV completion will critically depend on the availability of measurements from a wider variety of nuclear targets, including iodine or fluorine. We investigate how model-selection prospects depend on the energy window available for the analysis. In addition, we discuss accuracy of the DM particle mass determination under a wide variety of scattering models, and investigate impact of the specific types of particle-physics uncertainties on prospects for model selection.

  8. Identifying the theory of dark matter with direct detection

    NASA Astrophysics Data System (ADS)

    Gluscevic, Vera; Gresham, Moira I.; McDermott, Samuel D.; Peter, Annika H. G.; Zurek, Kathryn M.

    2015-12-01

    Identifying the true theory of dark matter depends crucially on accurately characterizing interactions of dark matter (DM) with other species. In the context of DM direct detection, we present a study of the prospects for correctly identifying the low-energy effective DM-nucleus scattering operators connected to UV-complete models of DM-quark interactions. We take a census of plausible UV-complete interaction models with different low-energy leading-order DM-nuclear responses. For each model (corresponding to different spin-, momentum-, and velocity-dependent responses), we create a large number of realizations of recoil-energy spectra, and use Bayesian methods to investigate the probability that experiments will be able to select the correct scattering model within a broad set of competing scattering hypotheses. We conclude that agnostic analysis of a strong signal (such as Generation-2 would see if cross sections are just below the current limits) seen on xenon and germanium experiments is likely to correctly identify momentum dependence of the dominant response, ruling out models with either "heavy" or "light" mediators, and enabling downselection of allowed models. However, a unique determination of the correct UV completion will critically depend on the availability of measurements from a wider variety of nuclear targets, including iodine or fluorine. We investigate how model-selection prospects depend on the energy window available for the analysis. In addition, we discuss accuracy of the DM particle mass determination under a wide variety of scattering models, and investigate impact of the specific types of particle-physics uncertainties on prospects for model selection.

  9. Constraint monitoring in TOSCA

    NASA Technical Reports Server (NTRS)

    Beck, Howard

    1992-01-01

    The Job-Shop Scheduling Problem (JSSP) deals with the allocation of resources over time to factory operations. Allocations are subject to various constraints (e.g., production precedence relationships, factory capacity constraints, and limits on the allowable number of machine setups) which must be satisfied for a schedule to be valid. The identification of constraint violations and the monitoring of constraint threats plays a vital role in schedule generation in terms of the following: (1) directing the scheduling process; and (2) informing scheduling decisions. This paper describes a general mechanism for identifying constraint violations and monitoring threats to the satisfaction of constraints throughout schedule generation.

  10. A FAST FLARE AND DIRECT REDSHIFT CONSTRAINT IN FAR-ULTRAVIOLET SPECTRA OF THE BLAZAR S5 0716+714

    SciTech Connect

    Danforth, Charles W.; Nalewajko, Krzysztof; France, Kevin; Keeney, Brian A.

    2013-02-10

    The BL Lacertae object S5 0716+714 is one of the most studied blazars on the sky due to its active variability and brightness in many bands, including very-high-energy gamma rays. We present here two serendipitous results from recent far-ultraviolet spectroscopic observations by the Cosmic Origins Spectrograph onboard the Hubble Space Telescope (HST). First, during the course of our 7.3 hr HST observations, the blazar increased in flux rapidly by {approx}40% (-0.45 mag hr{sup -1}) followed by a slower decline (+0.36 mag hr{sup -1}) to previous FUV flux levels. We model this flare using asymmetric flare templates and constrain the physical size and energetics of the emitting region. Furthermore, the spectral index of the object softens considerably during the course of the flare from {alpha}{sub {nu}} Almost-Equal-To -1.0 to {alpha}{sub {nu}} Almost-Equal-To -1.4. Second, we constrain the source redshift directly using the {approx}30 intervening absorption systems. A system at z = 0.2315 is detected in Ly{alpha}, Ly{beta}, O VI, and N V and defines the lower bound on the source redshift. No absorbers are seen in the remaining spectral coverage (0.2315 < z {sub Ly{alpha}} {approx}< 0.47) and we set a statistical upper bound of z < 0.322 (95% confidence) on the blazar. This is the first direct redshift limit for this object and is consistent with literature estimates of z = 0.31 {+-} 0.08 based on the detection of a host galaxy.

  11. Fine Structure ENA Sources Beyond the Termination Shock: Observational Constraints and Detection Limits

    NASA Astrophysics Data System (ADS)

    Demajistre, R.; Janzen, P. H.; Allegrini, F.; Dayeh, M. A.; McComas, D. J.; Schwadron, N.

    2015-12-01

    High spatial resolution maps from the IBEX mission (McComas et al, Science, 2009) suggest the presence of "fine structure" in the signal from beyond the termination shock. That is, areas of enhanced ENA emission that span less than a degree in the IBEX sky map. If confirmed, this would suggest very concentrated areas of emission from sources with scales of a few AU embedded in the outer heliosphere (or proportionally larger if they are located beyond the heliopause). This, in turn, would require the presence of unanticipated structures (plasma or neutral) beyond the termination shock for which the physics is poorly defined. It is therefore crucial to confirm the presence of these structures through careful analysis, or to establish the detection limits if the data taken to date is not sufficient for such a confirmation. In this work, we use 5 years worth of IBEX data to examine the statistical significance of these enhancements. We examine correlations in time, ENA energy and coincidence type for evidence of these small-scale spatial structures. Then, using the known spatial response of the IBEX instrument, establish the conditions under which such structure, if present, would be detectable. This detection threshold analysis is fully applicable future measurements, such as those planned for IMAP.

  12. Action change detection in video using a bilateral spatial-temporal constraint

    NASA Astrophysics Data System (ADS)

    Tian, Jing; Chen, Li

    2016-08-01

    Action change detection in video aims to detect action discontinuity in video. The silhouettes-based features are desirable for action change detection. This paper studies the problem of silhouette-quality assessment. For that, a non-reference approach without the need for ground truth is proposed in this paper to evaluate the quality of silhouettes, by exploiting both the boundary contrast of the silhouettes in the spatial domain and the consistency of the silhouettes in the temporal domain. This is in contrast to that either only spatial information or only temporal information of silhouettes is exploited in conventional approaches. Experiments are conducted using artificially generated degraded silhouettes to show that the proposed approach outperforms conventional approaches to achieve more accurate quality assessment. Furthermore, experiments are performed to show that the proposed approach is able to improve the accuracy performance of conventional action change approaches in two human action video data-sets. The average runtime of the proposed approach for Weizmann action video data-set is 0.08 second for one frame using Matlab programming language. It is computationally efficient and potential to real-time implementations.

  13. PDM-16QAM vector signal generation and detection based on intensity modulation and direct detection

    NASA Astrophysics Data System (ADS)

    Chen, Long; Yu, Jianjun; Li, Xinying

    2016-07-01

    We experimentally demonstrate a novel and simple method to generate and detect high speed polarization-division-multiplexing 16-ary quadrature-amplitude-modulation (PDM-16QAM) vector signal enabled by Mach-Zehnder modulator-based (MZM-based) optical-carrier-suppression (OCS) intensity modulation and direct detection. Due to the adoption of OCS intensity modulation, carrier beating can be avoided at the receiver, and thus polarization de-multiplexing can be implemented by digital-signal-processing-based (DSP-based) cascaded multi-modulus algorithm (CMMA) equalization instead of a polarization tracking system. The change of both amplitude and phase information due to the adoption of OCS modulation can be equalized by DSP-based amplitude and phase precoding at the transmitter. Up to 64-Gb/s PDM-16QAM vector signal is generated and detected after 2-km single-mode fiber-28 (SMF-28) or 20-km large-effective-area fiber (LEAF) transmission with a bit-error-ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8×10-3.

  14. Business-objective-directed, constraint-based multivariate optimization of high-performance liquid chromatography operational parameters.

    PubMed

    Chester, T L

    2003-10-24

    The goal of a separation can be defined in terms of business needs. One goal often used is to provide the required separation in minimum time, but many other goals are also possible. These include maximizing resolution within an analysis-time limit, or minimizing the overall cost. The remaining requirements of the separation can be applied as constraints in the optimization of the goal. We will present a flexible, business-objective-based approach for optimizing the operational parameters of high performance liquid chromatography (HPLC) methods. After selecting the stationary phase and the mobile-phase components, several isocratic experiments are required to build a retention model. Multivariate optimization is performed, within the model, to find the best combination of the parameters being varied so that the result satisfies the goal to the fullest extent possible within the constraints. Interdependencies of parameters can be revealed by plotting the loci of optimal variable values or the function being optimized against a constraint. We demonstrate the concepts with a model separation originally requiring a 54 min analysis time. Multivariate optimization reduces the predicted analysis time to as short as 8 min, depending on the goals and constraints specified. PMID:14601838

  15. Extended maximum likelihood halo-independent analysis of dark matter direct detection data

    SciTech Connect

    Gelmini, Graciela B.; Georgescu, Andreea; Gondolo, Paolo; Huh, Ji-Haeng

    2015-11-24

    We extend and correct a recently proposed maximum-likelihood halo-independent method to analyze unbinned direct dark matter detection data. Instead of the recoil energy as independent variable we use the minimum speed a dark matter particle must have to impart a given recoil energy to a nucleus. This has the advantage of allowing us to apply the method to any type of target composition and interaction, e.g. with general momentum and velocity dependence, and with elastic or inelastic scattering. We prove the method and provide a rigorous statistical interpretation of the results. As first applications, we find that for dark matter particles with elastic spin-independent interactions and neutron to proton coupling ratio f{sub n}/f{sub p}=−0.7, the WIMP interpretation of the signal observed by CDMS-II-Si is compatible with the constraints imposed by all other experiments with null results. We also find a similar compatibility for exothermic inelastic spin-independent interactions with f{sub n}/f{sub p}=−0.8.

  16. Target detection in GPR data using joint low-rank and sparsity constraints

    NASA Astrophysics Data System (ADS)

    Bouzerdoum, Abdesselam; Tivive, Fok Hing Chi; Abeynayake, Canicious

    2016-05-01

    In ground penetrating radars, background clutter, which comprises the signals backscattered from the rough, uneven ground surface and the background noise, impairs the visualization of buried objects and subsurface inspections. In this paper, a clutter mitigation method is proposed for target detection. The removal of background clutter is formulated as a constrained optimization problem to obtain a low-rank matrix and a sparse matrix. The low-rank matrix captures the ground surface reflections and the background noise, whereas the sparse matrix contains the target reflections. An optimization method based on split-Bregman algorithm is developed to estimate these two matrices from the input GPR data. Evaluated on real radar data, the proposed method achieves promising results in removing the background clutter and enhancing the target signature.

  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. Recent Results in Dark Matter Direct Detection Experiments

    SciTech Connect

    Kelso, Christopher Michael

    2012-08-01

    In this dissertation, we study the original excess of low energy events observed by the Co- GeNT collaboration and the annual modulation reported by the DAMA/LIBRA collaboration, and discuss whether these signals could both be the result of the same elastically scattering dark matter particle. We find that, without channeling but when taking into account uncertainties in the relevant quenching factors, a dark matter candidate with a mass of approximately ~7.0 GeV and a cross section with nucleons of σDM-N ~2 x 10-40 cm2 could account for both of these observations. We also compare the region of parameter space favored by DAMA/LIBRA and CoGeNT to the constraints from XENON 10, XENON 100, and CDMS (Si).

  19. Comparison of IPDA lidar receiver sensitivity for coherent detection and for direct detection using sine-wave and pulsed modulation.

    PubMed

    Sun, Xiaoli; Abshire, James B

    2012-09-10

    We use theoretical models to compare the receiver signal to noise ratio (SNR) vs. average rate of detected signal photons for an integrated path differential absorption (IPDA) lidar using coherent detection with continuous wave (CW) lasers and direct detection with sine-wave and pulse modulations. The results show the coherent IPDA lidar has high receiver gain and narrow bandwidth to overcome the effects of detector circuit noise and background light, but the actual receiver performance can be limited by the coherent mixing efficiency, speckle and other factors. For direct detection, using sine-wave modulation allows the use of a low peak power laser transmitter and synchronous detection. The pulse modulation technique requires higher laser peak powers but is more efficient than sine-wave modulation in terms of average detected signal photon rate required to achieve a given receiver SNR. We also conducted experiments for the direct detection cases and the results agreed well with theory.

  20. Bed bug detection: current technologies and future directions.

    PubMed

    Vaidyanathan, Rajeev; Feldlaufer, Mark F

    2013-04-01

    Technologies to detect bed bugs have not kept pace with their global resurgence. Early detection is critical to prevent infestations from spreading. Detection based exclusively on bites is inadequate, because reactions to insect bites are non-specific and often misdiagnosed. Visual inspections are commonly used and depend on identifying live bugs, exuviae, or fecal droplets. Visual inspections are inexpensive, but they are time-consuming and unreliable when only a few bugs are present. Use of a dog to detect bed bugs is gaining in popularity, but it can be expensive, may unintentionally advertise a bed bug problem, and is not foolproof. Passive monitors mimic natural harborages; they are discreet and typically use an adhesive to trap bugs. Active monitors generate carbon dioxide, heat, a pheromone, or a combination to attract bed bugs to a trap. New technologies using DNA analysis, mass spectrometry, and electronic noses are innovative but impractical and expensive for widespread use. PMID:23553226

  1. Bed Bug Detection: Current Technologies and Future Directions

    PubMed Central

    Vaidyanathan, Rajeev; Feldlaufer, Mark F.

    2013-01-01

    Technologies to detect bed bugs have not kept pace with their global resurgence. Early detection is critical to prevent infestations from spreading. Detection based exclusively on bites is inadequate, because reactions to insect bites are non-specific and often misdiagnosed. Visual inspections are commonly used and depend on identifying live bugs, exuviae, or fecal droplets. Visual inspections are inexpensive, but they are time-consuming and unreliable when only a few bugs are present. Use of a dog to detect bed bugs is gaining in popularity, but it can be expensive, may unintentionally advertise a bed bug problem, and is not foolproof. Passive monitors mimic natural harborages; they are discreet and typically use an adhesive to trap bugs. Active monitors generate carbon dioxide, heat, a pheromone, or a combination to attract bed bugs to a trap. New technologies using DNA analysis, mass spectrometry, and electronic noses are innovative but impractical and expensive for widespread use. PMID:23553226

  2. MSSM A-funnel and the galactic center excess: prospects for the LHC and direct detection experiments

    NASA Astrophysics Data System (ADS)

    Freese, Katherine; López, Alejandro; Shah, Nausheen R.; Shakya, Bibhushan

    2016-04-01

    The pseudoscalar resonance or " A-funnel" in the Minimal Supersymmetric Standard Model (MSSM) is a widely studied framework for explaining dark matter that can yield interesting indirect detection and collider signals. The well-known Galactic Center excess (GCE) at GeV energies in the gamma ray spectrum, consistent with annihilation of a ≲ 40 GeV dark matter particle, has more recently been shown to be compatible with significantly heavier masses following reanalysis of the background. In this paper, we explore the LHC and direct detection implications of interpreting the GCE in this extended mass window within the MSSM A-funnel framework. We find that compatibility with relic density, signal strength, collider constraints, and Higgs data can be simultaneously achieved with appropriate parameter choices. The compatible regions give very sharp predictions of 200-600 GeV CP-odd/even Higgs bosons at low tan β at the LHC and spin-independent cross sections ≈ 10-11 pb at direct detection experiments. Regardless of consistency with the GCE, this study serves as a useful template of the strong correlations between indirect, direct, and LHC signatures of the MSSM A-funnel region.

  3. MSSM A-funnel and the galactic center excess: prospects for the LHC and direct detection experiments

    DOE PAGESBeta

    Freese, Katherine; López, Alejandro; Shah, Nausheen R.; Shakya, Bibhushan

    2016-04-11

    The pseudoscalar resonance or “A-funnel” in the Minimal Supersymmetric Standard Model (MSSM) is a widely studied framework for explaining dark matter that can yield interesting indirect detection and collider signals. The well-known Galactic Center excess (GCE) at GeV energies in the gamma ray spectrum, consistent with annihilation of a ≲ 40 GeV dark matter particle, has more recently been shown to be compatible with significantly heavier masses following reanalysis of the background.For this study, we explore the LHC and direct detection implications of interpreting the GCE in this extended mass window within the MSSM A-funnel framework. We find that compatibilitymore » with relic density, signal strength, collider constraints, and Higgs data can be simultaneously achieved with appropriate parameter choices. The compatible regions give very sharp predictions of 200-600 GeV CP-odd/even Higgs bosons at low tan β at the LHC and spin-independent cross sections ≈ 10-11 pb at direct detection experiments. Finally, regardless of consistency with the GCE, this study serves as a useful template of the strong correlations between indirect, direct, and LHC signatures of the MSSM A-funnel region.« less

  4. Update on the direct detection of supersymmetric dark matter

    SciTech Connect

    Ellis, John; Olive, Keith A.; Spanos, Vassilis C.; Santoso, Yudi

    2005-05-01

    We compare updated predictions for the elastic scattering of supersymmetric neutralino dark matter with the improved experimental upper limit recently published by Cryogenic Dark Matter Search (CDMS) II. We take into account the possibility that the {pi}-nucleon {sigma} term may be somewhat larger than was previously considered plausible, as may be supported by the masses of exotic baryons reported recently. We also incorporate the new central value of m{sub t}, which affects indirectly constraints on the supersymmetric parameter space, for example, via calculations of the relic density. Even if a large value of {sigma} is assumed, the CDMS II data currently exclude only small parts of the parameter space in the constrained minimal standard model (CMSSM) with universal soft supersymmetry-breaking Higgs, squark, and slepton masses. None of the previously proposed CMSSM benchmark scenarios is excluded for any value of {sigma}, and the CDMS II data do not impinge on the domains of the CMSSM parameter space favored at the 90% confidence level in a recent likelihood analysis. However, some models with nonuniversal Higgs, squark, and slepton masses and neutralino masses < or approx. 700 GeV are excluded by the CDMS II data.

  5. A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology

    PubMed Central

    Klopfstein, Seraina; Vilhelmsen, Lars; Ronquist, Fredrik

    2015-01-01

    Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1–0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology. PMID:26272507

  6. A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology.

    PubMed

    Klopfstein, Seraina; Vilhelmsen, Lars; Ronquist, Fredrik

    2015-11-01

    Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1-0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology.

  7. 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.

  8. 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.

  9. The Higgs boson in the Standard Model theoretical constraints and a direct search in the wh channel at the Tevatron

    SciTech Connect

    Huske, Nils Kristian

    2010-09-10

    We have presented results in two different yet strongly linked aspects of Higgs boson physics. We have learned about the importance of the Higgs boson for the fate of the Standard Model, being either only a theory limited to explaining phenomena at the electroweak scale or, if the Higgs boson lies within a mass range of 130 < mH < 160 GeV the SM would remain a self consistent theory up to highest energy scales O(mPl). This could have direct implications on theories of cosmological inflation using the Higgs boson as the particle giving rise to inflation in the very early Universe, if it couples non-minimally to gravity, an effect that would only become significant at very high energies. After understanding the immense meaning of proving whether the Higgs boson exists and if so, at which mass, we have presented a direct search for a Higgs boson in associated production with a W boson in a mass range 100 < mH < 150 GeV. A light Higgs boson is favored regarding constraints from electroweak precision measurements. As a single analysis is not yet sensitive for an observation of the Higgs boson using 5.3 fb-1 of Tevatron data, we set limits on the production cross section times branching ratio. At the Tevatron, however, we are able to combine the sensitivity of our analyses not only across channels or analyses at a single experiment but also across both experiments, namely CDF and D0. This yields to the so-called Tevatron Higgs combination which, in total, combines 129 analyses from both experiments with luminosities of up to 6.7 fb-1. The results of a previous Tevatron combination led to the first exclusion of possible Higgs boson masses since the LEP exclusion in 2001. The latest Tevatron combination from July 2010 can be seen in Fig. 111 and limits compared to the Standard Model expectation are listed in Table 23. It excludes a SM Higgs boson in the regions of 100 < mH < 109 GeV as well as 158 < m

  10. Direct detection of RDX vapor using a conjugated polymer network.

    PubMed

    Gopalakrishnan, Deepti; Dichtel, William R

    2013-06-01

    1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) is a principal component of plastic explosives used in acts of terrorism and within improvised explosive devices, among others. Approaches to detect RDX compatible with remote, "stand-off" sampling that do not require preconcentration strategies, such as the swabs commonly employed in airports, will benefit military and civilian security. Such detection remains a significant challenge because RDX is 10(3) less volatile than 1,3,5-trinitrotoluene (TNT), corresponding to a parts-per-trillion vapor pressure under ambient conditions. Therefore, while fluorescence quenching of conjugated polymers is sufficiently sensitive to detect TNT vapors, RDX vapor detection is undemonstrated. Here we report a cross-linked phenylene vinylene polymer network whose fluorescence is quenched by trace amounts of RDX introduced from solution or the vapor phase. Fluorescence quenching is reduced, but remains significant, when partially degraded RDX is employed, suggesting that the polymer responds to RDX itself. The polymer network also responds to TNT and PETN similarly introduced from solution or the vapor phase. Pure solvents, volatile amines, and the outgassed vapors from lipstick or sunscreen do not quench polymer fluorescence. The established success of TNT sensors based on fluorescence quenching makes this a material of interest for real-world explosive sensors and will motivate further interest in cross-linked polymers and framework materials for sensing applications. PMID:23641956

  11. Direct Detections of the Yarkovsky Effect: Status and Outlook

    NASA Astrophysics Data System (ADS)

    Chesley, Steven R.; Farnocchia, Davide; Pravec, Petr; Vokrouhlický, David

    2016-01-01

    We report the current results on a comprehensive scan of the near-Earth asteroid catalog for evidence of the Yarkovsky effect in the orbital motion of these bodies. While most objects do not have sufficient observational data to reveal such slight acceleration, we do identify 42 asteroids with a ``valid'' detection of the Yarkovsky effect, i.e., those with a signal at least 3 times greater than the formal uncertainty and a value compatible with the Yarkovsky mechanism. We also identify a special category of non-detection, which we refer to as ``weak signal,'' where the objects are of a size that would permit a clear detection if the Yarkovsky effect is maximized, and yet the orbit is clearly incompatible with such accelerations. The implication is that the Yarkovsky effect is reduced in these cases, presumably due to mid-range obliquity, but possibly also due to size, bulk density, thermal inertia, albedo, or spin rate markedly different from assumptions. Finally, there are a number of asteroids showing a significant signal for nongravitational acceleration, and yet with a magnitude too great to be attributed to the Yarkovsky effect. We term these ``spurious detections'' because most are due to erroneous optical astrometry, often involving a single isolated night from precovery observations. Some cases may be due to other nongravitational accelerations, such as outgassing, mass loss, or micro-meteoroid flux.

  12. Simplified Protocol for Carba NP Test for Enhanced Detection of Carbapenemase Producers Directly from Bacterial Cultures.

    PubMed

    Pasteran, Fernando; Tijet, Nathalie; Melano, Roberto G; Corso, Alejandra

    2015-12-01

    We compared carbapenemase detection among 266 Gram-negative bacilli (161 carbapenemase producers) using the Carba NP tests issued by the CLSI (CNPt-CLSI) and a novel protocol (CNPt-direct) designed for carbapenemase detection direct from bacterial cultures (instead of bacterial extracts required by the CLSI tests). The specificities were comparable (100%), but the CNPt-direct was more sensitive (98% versus 84%). The CNPt-direct was easier to perform due to the direct use of colonies and offered a more robust detection of carbapenemase producers.

  13. Simplified Protocol for Carba NP Test for Enhanced Detection of Carbapenemase Producers Directly from Bacterial Cultures

    PubMed Central

    Pasteran, Fernando; Tijet, Nathalie; Melano, Roberto G.

    2015-01-01

    We compared carbapenemase detection among 266 Gram-negative bacilli (161 carbapenemase producers) using the Carba NP tests issued by the CLSI (CNPt-CLSI) and a novel protocol (CNPt-direct) designed for carbapenemase detection direct from bacterial cultures (instead of bacterial extracts required by the CLSI tests). The specificities were comparable (100%), but the CNPt-direct was more sensitive (98% versus 84%). The CNPt-direct was easier to perform due to the direct use of colonies and offered a more robust detection of carbapenemase producers. PMID:26424841

  14. Simplified Protocol for Carba NP Test for Enhanced Detection of Carbapenemase Producers Directly from Bacterial Cultures.

    PubMed

    Pasteran, Fernando; Tijet, Nathalie; Melano, Roberto G; Corso, Alejandra

    2015-12-01

    We compared carbapenemase detection among 266 Gram-negative bacilli (161 carbapenemase producers) using the Carba NP tests issued by the CLSI (CNPt-CLSI) and a novel protocol (CNPt-direct) designed for carbapenemase detection direct from bacterial cultures (instead of bacterial extracts required by the CLSI tests). The specificities were comparable (100%), but the CNPt-direct was more sensitive (98% versus 84%). The CNPt-direct was easier to perform due to the direct use of colonies and offered a more robust detection of carbapenemase producers. PMID:26424841

  15. When does female multiple mating evolve to adjust inbreeding? Effects of inbreeding depression, direct costs, mating constraints, and polyandry as a threshold trait.

    PubMed

    Duthie, A Bradley; Bocedi, Greta; Reid, Jane M

    2016-09-01

    Polyandry is often hypothesized to evolve to allow females to adjust the degree to which they inbreed. Multiple factors might affect such evolution, including inbreeding depression, direct costs, constraints on male availability, and the nature of polyandry as a threshold trait. Complex models are required to evaluate when evolution of polyandry to adjust inbreeding is predicted to arise. We used a genetically explicit individual-based model to track the joint evolution of inbreeding strategy and polyandry defined as a polygenic threshold trait. Evolution of polyandry to avoid inbreeding only occurred given strong inbreeding depression, low direct costs, and severe restrictions on initial versus additional male availability. Evolution of polyandry to prefer inbreeding only occurred given zero inbreeding depression and direct costs, and given similarly severe restrictions on male availability. However, due to its threshold nature, phenotypic polyandry was frequently expressed even when strongly selected against and hence maladaptive. Further, the degree to which females adjusted inbreeding through polyandry was typically very small, and often reflected constraints on male availability rather than adaptive reproductive strategy. Evolution of polyandry solely to adjust inbreeding might consequently be highly restricted in nature, and such evolution cannot necessarily be directly inferred from observed magnitudes of inbreeding adjustment. PMID:27464756

  16. When does female multiple mating evolve to adjust inbreeding? Effects of inbreeding depression, direct costs, mating constraints, and polyandry as a threshold trait

    PubMed Central

    Duthie, A. Bradley; Bocedi, Greta; Reid, Jane M.

    2016-01-01

    Polyandry is often hypothesized to evolve to allow females to adjust the degree to which they inbreed. Multiple factors might affect such evolution, including inbreeding depression, direct costs, constraints on male availability, and the nature of polyandry as a threshold trait. Complex models are required to evaluate when evolution of polyandry to adjust inbreeding is predicted to arise. We used a genetically explicit individual‐based model to track the joint evolution of inbreeding strategy and polyandry defined as a polygenic threshold trait. Evolution of polyandry to avoid inbreeding only occurred given strong inbreeding depression, low direct costs, and severe restrictions on initial versus additional male availability. Evolution of polyandry to prefer inbreeding only occurred given zero inbreeding depression and direct costs, and given similarly severe restrictions on male availability. However, due to its threshold nature, phenotypic polyandry was frequently expressed even when strongly selected against and hence maladaptive. Further, the degree to which females adjusted inbreeding through polyandry was typically very small, and often reflected constraints on male availability rather than adaptive reproductive strategy. Evolution of polyandry solely to adjust inbreeding might consequently be highly restricted in nature, and such evolution cannot necessarily be directly inferred from observed magnitudes of inbreeding adjustment. PMID:27464756

  17. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  18. Protein-based nanobiosensor for direct detection of hydrogen sulfide

    NASA Astrophysics Data System (ADS)

    Omidi, Meisam; Amoabediny, Ghasem; Yazdian, Fatemeh; Habibi-Rezaei, M.

    2015-01-01

    The chemically modified cytochrome c from equine heart, EC (232-700-9), was immobilized onto gold nanoparticles in order to develop a specific biosensing system for monitoring hydrogen sulfide down to the micromolar level, by means of a localized surface plasmon resonance spectroscopy. The sensing mechanism is based on the cytochrome-c conformational changes in the presence of H2S which alter the dielectric properties of the gold nanoparticles and the surface plasmon resonance peak undergoes a redshift. According to the experiments, it is revealed that H2S can be detected at a concentration of 4.0 μ \\text{M} (1.3 \\text{ppb}) by the fabricated biosensor. This simple, quantitative and sensitive sensing platform provides a rapid and convenient detection for H2S at concentrations far below the hazardous limit.

  19. Aptamer beacons for the direct detection of proteins.

    PubMed

    Hamaguchi, N; Ellington, A; Stanton, M

    2001-07-15

    We have designed a new class of molecules, which we term aptamer beacons, for detecting a wide range of ligands. Similar to molecular beacons, aptamer beacons can adopt two or more conformations, one of which allows ligand binding. A fluorescence-quenching pair is used to report changes in conformation induced by ligand binding. An anti-thrombin aptamer was engineered into an aptamer beacon by adding nucleotides to the 5'-end which are complementary to nucleotides at the 3'-end of the aptamer. In the absence of thrombin, the added nucleotides will form a duplex with the 3'-end, forcing the aptamer beacon into a stem-loop structure. In the presence of thrombin, the aptamer beacon forms the ligand-binding structure. This conformational change causes a change in the distance between a fluorophore attached to the 5'-end and a quencher attached to the 3'-end. Aptamer beacon can be a sensitive tool for detecting proteins and other chemical compounds.

  20. Rapid Detection and Identification of Respiratory Viruses by Direct Immunofluorescence

    PubMed Central

    D'Alessio, Donn; Williams, Stanley; Dick, Elliot C.

    1970-01-01

    The use of fluorescein-conjugated antiserum against respiratory syncytial (RS) and parainfluenza 1 and 3 viruses was compared with conventional techniques in the rapid detection of virus in tissue cultures inoculated with pharyngeal specimens known to contain these viruses. Twenty-three specimens were tested: 9 RS, 8 parainfluenza 1, and 6 parainfluenza 3. The fluorescent-antibody technique (FA) detected virus in 52% of the tissue cultures in 24 hr, and, by 72 hr, 22 of the 23 cultures were FA-positive whereas only 5 were positive by conventional techniques. Additionally, conjugated antisera were prepared against herpes simplex, influenza A2, and adenovirus type 5. All conjugates stained only the homologous virus and were 100- to 10,000-fold more sensitive than conventional techniques in detecting descending dilutions of virus inocula by 24 hr. With the procedures described, several antisera could be conjugated and ready for use within 24 hr. Serum fractionation was by ammonium sulfate precipitation, and with the procedure outlined virtually complete recovery of the globulin fraction and elimination of all of the albumin were accomplished. Images PMID:4098101

  1. The detection of transient directional couplings based on phase synchronization

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Fell, J.; Lehnertz, K.

    2010-05-01

    We extend recent approaches based on the concept of phase synchronization to enable the time-resolved investigation of directional relationships between coupled dynamical systems from short and transient noisy time series. For our approach, we consider an observed ensemble of a sufficiently large number of time series as multiple realizations of a process. We derive an index that quantifies the direction of transient interactions and assess its statistical significance using surrogate techniques. Analysing time series from noisy and chaotic systems, we demonstrate numerically the applicability and limitations of our approach. Our findings from an exemplary application to event-related brain activities underline the importance of our method for improving knowledge about the mechanisms underlying memory formation in humans.

  2. Teleconnection Paths via Climate Network Direct Link Detection.

    PubMed

    Zhou, Dong; Gozolchiani, Avi; Ashkenazy, Yosef; Havlin, Shlomo

    2015-12-31

    Teleconnections describe remote connections (typically thousands of kilometers) of the climate system. These are of great importance in climate dynamics as they reflect the transportation of energy and climate change on global scales (like the El Niño phenomenon). Yet, the path of influence propagation between such remote regions, and weighting associated with different paths, are only partially known. Here we propose a systematic climate network approach to find and quantify the optimal paths between remotely distant interacting locations. Specifically, we separate the correlations between two grid points into direct and indirect components, where the optimal path is found based on a minimal total cost function of the direct links. We demonstrate our method using near surface air temperature reanalysis data, on identifying cross-latitude teleconnections and their corresponding optimal paths. The proposed method may be used to quantify and improve our understanding regarding the emergence of climate patterns on global scales. PMID:26765033

  3. Additional sampling directions improve detection range of wireless radiofrequency probes

    PubMed Central

    Mada, Marius; Carpenter, T. Adrian; Sawiak, Stephen J.; Williams, Guy B.

    2015-01-01

    Purpose While MRI is enhancing our knowledge about the structure and function of the human brain, subject motion remains a problem in many clinical applications. Recently, the use of wireless radiofrequency markers with three one‐dimensional (1D) navigators for prospective correction was demonstrated. This method is restricted in the range of motion that can be corrected, however, because of limited information in the 1D readouts. Methods Here, the limitation of techniques for disambiguating marker locations was investigated. It was shown that including more sampling directions extends the tracking range for head rotations. The efficiency of trading readout resolution for speed was explored. Results Tracking of head rotations was demonstrated from −19.2 to 34.4°, −2.7 to 10.0°, and −60.9 to 70.9° in the x‐, y‐, and z‐directions, respectively. In the presence of excessive head motion, the deviation of marker estimates from SPM8 was reduced by 17.1% over existing three‐projection methods. This was achieved by using an additional seven directions, extending the time needed for readouts by a factor of 3.3. Much of this increase may be circumvented by reducing resolution, without compromising accuracy. Conclusion Including additional sampling directions extends the range in which markers can be used, for patients who move a lot. Magn Reson Med 76:913–918, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26418189

  4. Direct detection of exoplanets and circumstellar disks using NaCo APP and NaCo PDI

    NASA Astrophysics Data System (ADS)

    Quanz, S. P.; Meyer, M. R.; Kenworthy, M.; Kasper, M.; Lenzen, R.; Girard, J.; Hinz, P.; Geissler, K.; Brander, W.; Henning, T.; Wolf, S.

    2010-10-01

    The direct detection of faint objects close to a bright star (such as circumstellar disks or exoplanets) is observationally challenging as it requires both, high spatial resolution and high contrast. However, it is exactly these resolved images that boost our understanding of the nature and underlying physics of the corresponding objects. In this talk we will present new results obtained with the versatile NaCo instrument at the VLT. In the first part, we report on recent observations with the newly installed apodizing phase plate (APP) coronagraph aiming at the direct detection of exoplanets at 4 micron. We confirm the detection of beta Pic b and add additional information to the orbit and atmospheric properties of the planet. Additional ongoing studies are briefly discussed. In the second part, we present the results from a mini-survey to resolve circumstellar disks using polarimetric differential imaging (PDI) in the near infrared. Among other targets we show resolved images of the prominent circumstellar disk around the young Herbig Be star HD100546. The images reveal the disk at unprecedented inner working angles. Having polarimetric information in different filters allows us to put constraints on dust grain properties and disk geometry in previously unaccessible disk regions. In addition to their scientific merit, the studies mentioned above will demonstrate the benefits - but also the limitations - of both techniques (APP and PDI). This will help to better determine their potential role in high contrast imaging with future facilities such as VLT/SPHERE and E-ELT.

  5. Detection of nucleic acid sequences by invader-directed cleavage

    DOEpatents

    Brow, Mary Ann D.; Hall, Jeff Steven Grotelueschen; Lyamichev, Victor; Olive, David Michael; Prudent, James Robert

    1999-01-01

    The present invention relates to means for the detection and characterization of nucleic acid sequences, as well as variations in nucleic acid sequences. The present invention also relates to methods for forming a nucleic acid cleavage structure on a target sequence and cleaving the nucleic acid cleavage structure in a site-specific manner. The 5' nuclease activity of a variety of enzymes is used to cleave the target-dependent cleavage structure, thereby indicating the presence of specific nucleic acid sequences or specific variations thereof. The present invention further relates to methods and devices for the separation of nucleic acid molecules based by charge.

  6. 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.

  7. 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.

  8. Direct detection of relic active and sterile neutrinos

    NASA Astrophysics Data System (ADS)

    Li, Yu-Feng

    2016-05-01

    Both active and sterile sub-eV neutrinos can form the cosmic neutrino background in the early Universe. We consider the beta-decaying (e.g., 3H) and EC-decaying (e.g., 163Ho) nuclei as the promising targets to capture relic neutrinos in the laboratory. We calculate the capture rates of relic electron neutrinos and antineutrinos against the corresponding beta decay or electron capture (EC) decay backgrounds in the (3+Ns) flavor mixing scheme, and discuss the future prospect in terms of the PTOLEMY project. We stress that such direct measurements of hot DM might not be hopeless in the long term.

  9. A prototype direct-detection CCD for protein crystallography

    PubMed Central

    Green, Katherine S.; Szebenyi, Doletha M. E.; Boggs, Kasey; Bredthauer, Richard; Tate, Mark W.; Gruner, Sol M.

    2013-01-01

    The fabrication and testing of a prototype deep-depletion direct-conversion X-ray CCD detector are described. The device is fabricated on 600 µm-thick high-resistivity silicon, with 24 × 24 µm pixels in a 4k × 4k pixel format. Calibration measurements and the results of initial protein crystallography experiments at the Cornell High Energy Synchrotron Source (CHESS) F1 beamline are described, as well as suggested improvements for future versions of the detector. PMID:24046505

  10. Direct detection of a single photon by humans.

    PubMed

    Tinsley, Jonathan N; Molodtsov, Maxim I; Prevedel, Robert; Wartmann, David; Espigulé-Pons, Jofre; Lauwers, Mattias; Vaziri, Alipasha

    2016-01-01

    Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds. PMID:27434854

  11. Direct detection of a single photon by humans

    PubMed Central

    Tinsley, Jonathan N.; Molodtsov, Maxim I.; Prevedel, Robert; Wartmann, David; Espigulé-Pons, Jofre; Lauwers, Mattias; Vaziri, Alipasha

    2016-01-01

    Despite investigations for over 70 years, the absolute limits of human vision have remained unclear. Rod cells respond to individual photons, yet whether a single-photon incident on the eye can be perceived by a human subject has remained a fundamental open question. Here we report that humans can detect a single-photon incident on the cornea with a probability significantly above chance. This was achieved by implementing a combination of a psychophysics procedure with a quantum light source that can generate single-photon states of light. We further discover that the probability of reporting a single photon is modulated by the presence of an earlier photon, suggesting a priming process that temporarily enhances the effective gain of the visual system on the timescale of seconds. PMID:27434854

  12. Frequency-agile bandpass filter for direct detection lidar receivers.

    PubMed

    Gittins, C M; Lawrence, W G; Marinelli, W J

    1998-12-20

    We discuss the development of a frequency-agile receiver for CO(2) laser-based differential absorption lidar (DIAL) systems. The receiver is based on the insertion of a low-order tunable etalon into the detector field of view. The incorporation of the etalon into the receiver reduces system noise by decreasing the instantaneous spectral bandwidth of the IR detector to a narrow wavelength range centered on the transmitted CO(2) laser line, thereby improving the overall D* of the detection system. A consideration of overall lidar system performance results in a projected factor of a 2-7 reduction in detector system noise, depending on the characteristics of the environment being probed. These improvements can play a key role in extending the ability of DIAL systems to monitor chemical releases from long standoff distances.

  13. Xenon bubble chambers for direct dark matter detection

    NASA Astrophysics Data System (ADS)

    Levy, C.; Fallon, S.; Genovesi, J.; Khaitan, D.; Klimov, K.; Mock, J.; Szydagis, M.

    2016-03-01

    The search for dark matter is one of today's most exciting fields. As bigger detectors are being built to increase their sensitivity, background reduction is an ever more challenging issue. To this end, a new type of dark matter detector is proposed, a xenon bubble chamber, which would combine the strengths of liquid xenon TPCs, namely event by event energy resolution, with those of a bubble chamber, namely insensitivity to electronic recoils. In addition, it would be the first time ever that a dark matter detector is active on all three detection channels, ionization and scintillation characteristic of xenon detectors, and heat through bubble formation in superheated fluids. Preliminary simulations show that, depending on threshold, a discrimination of 99.99% to 99.9999+% can be achieved, which is on par or better than many current experiments. A prototype is being built at the University at Albany, SUNY. The prototype is currently undergoing seals, thermal, and compression testing.

  14. CRISPRdigger: detecting CRISPRs with better direct repeat annotations.

    PubMed

    Ge, Ruiquan; Mai, Guoqin; Wang, Pu; Zhou, Manli; Luo, Youxi; Cai, Yunpeng; Zhou, Fengfeng

    2016-01-01

    Clustered regularly interspaced short palindromic repeats (CRISPRs) are important genetic elements in many bacterial and archaeal genomes, and play a key role in prokaryote immune systems' fight against invasive foreign elements. The CRISPR system has also been engineered to facilitate target gene editing in eukaryotic genomes. Using the common features of mis-annotated CRISPRs in prokaryotic genomes, this study proposed an accurate de novo CRISPR annotation program CRISPRdigger, which can take a partially assembled genome as its input. A comprehensive comparison with the three existing programs demonstrated that CRISPRdigger can recover more Direct Repeats (DRs) for CRISPRs and achieve a higher accuracy for a query genome. The program was implemented by Perl and all the parameters had default values, so that a user could annotate CRISPRs in a query genome by supplying only a genome sequence in the FASTA format. All the supplementary data are available at http://www.healthinformaticslab.org/supp/. PMID:27596864

  15. Direct detection of variable tropospheric clouds near Titan's south pole.

    PubMed

    Brown, Michael E; Bouchez, Antonin H; Griffith, Caitlin A

    Atmospheric conditions on Saturn's largest satellite, Titan, allow the possibility that it could possess a methane condensation and precipitation cycle with many similarities to Earth's hydrological cycle. Detailed imaging studies of Titan have hitherto shown no direct evidence for tropospheric condensation clouds, although there has been indirect spectroscopic evidence for transient clouds. Here we report images and spectra of Titan that show clearly transient clouds, concentrated near the south pole, which is currently near the point of maximum solar heating. The discovery of these clouds demonstrates the existence of condensation and localized moist convection in Titan's atmosphere. Their location suggests that methane cloud formation is controlled seasonally by small variations in surface temperature, and that the clouds will move from the south to the north pole on a 15-year timescale.

  16. CRISPRdigger: detecting CRISPRs with better direct repeat annotations

    PubMed Central

    Ge, Ruiquan; Mai, Guoqin; Wang, Pu; Zhou, Manli; Luo, Youxi; Cai, Yunpeng; Zhou, Fengfeng

    2016-01-01

    Clustered regularly interspaced short palindromic repeats (CRISPRs) are important genetic elements in many bacterial and archaeal genomes, and play a key role in prokaryote immune systems’ fight against invasive foreign elements. The CRISPR system has also been engineered to facilitate target gene editing in eukaryotic genomes. Using the common features of mis-annotated CRISPRs in prokaryotic genomes, this study proposed an accurate de novo CRISPR annotation program CRISPRdigger, which can take a partially assembled genome as its input. A comprehensive comparison with the three existing programs demonstrated that CRISPRdigger can recover more Direct Repeats (DRs) for CRISPRs and achieve a higher accuracy for a query genome. The program was implemented by Perl and all the parameters had default values, so that a user could annotate CRISPRs in a query genome by supplying only a genome sequence in the FASTA format. All the supplementary data are available at http://www.healthinformaticslab.org/supp/. PMID:27596864

  17. Single-particle cryo-EM data acquisition by using direct electron detection camera.

    PubMed

    Wu, Shenping; Armache, Jean-Paul; Cheng, Yifan

    2016-02-01

    Recent advances in single-particle electron cryo-microscopy (cryo-EM) were largely facilitated by the application of direct electron detection cameras. These cameras feature not only a significant improvement in detective quantum efficiency but also a high frame rate that enables images to be acquired as 'movies' made of stacks of many frames. In this review, we discuss how the applications of direct electron detection cameras in cryo-EM have changed the way the data are acquired.

  18. A direct immunoassay for detecting diatoms in groundwater as an indicator of the direct influence of surface water

    USGS Publications Warehouse

    Walker, C.E.; Schrock, R.M.; Reilly, T.J.; Baehr, A.L.

    2005-01-01

    Groundwater under the direct influence of surface water (GWUDISW) is of concern in communities where growing public demand on groundwater resources has resulted in increased withdrawals and hydraulic stress near surface water bodies. Under these conditions, contaminants such as methyl-tert butyl ether (MTBE) and biological materials have been detected in domestic wells. Other contaminants and pathogens associated with surface water are not routinely tested for in groundwater-supplied systems. To address the need for methods to easily identify potentially vulnerable supplies, a direct immunoassay for the quantitative detection of diatoms in raw water samples was developed as a measure of surface water influence on groundwater. Cell wall preparations from Nitzschia palea Ku??tzing, a freshwater diatom found throughout North America, were used to produce a polyclonal antibody that was applied in a direct enzyme-linked immunosorbent assay (ELISA) developed to detect the presence of N. palea cell wall components. The direct immunoassay allows detection at 500 cells L-1, a level similar to diatom concentrations observed in samples of groundwater collected near the test site. This investigation was the first attempt to utilize an ELISA as an indicator of surface water influence on groundwater. Further research is needed to develop more specific diatom-based monoclonal antibodies, determine cross-reactivity, and optimize sample processing and ELISA procedures for development of a standardized method. ?? Springer 2005.

  19. First Direct Detection of Clay Minerals on Mars

    NASA Technical Reports Server (NTRS)

    Singer, R. B.; Owensby, P. D.; Clark, R. N.

    1985-01-01

    Magnesian clays or clay-type minerals were conclusively detected in the martian regolith. Near-IR spectral observations of Mars using the Mauna Kea 2.2-m telescope show weak but definite absorption bands near microns. The absorption band positions and widths match those produced by combined OH stretch and Mg-OH lattice modes and are diagnostic of minerals with structural OH such as clays and amphiboles. Likely candidate minerals include serpentine, talc, hectorite, and sponite. There is no spectral evidence for aluminous hydroxylated minerals. No distinct band occurs at 2.55 microns, as would be expected if carbonates were responsible for the 2.35 micron absorption. High-albedo regions such as Elysium and Utopia have the strongest bands near 2.35 microns, as would be expected for heavily weathered soils. Low-albedo regions such as Iapygia show weaker but distinct bands, consistent with moderate coatings, streaks, and splotches of bright weathered material. In all areas observed, the 2.35-micron absorption is at least three times weaker than would be expected if well-crystallized clay minerals made up the bulk of bright soils on Mars.

  20. Detecting biological responses to flow management: Missed opportunities; future directions

    USGS Publications Warehouse

    Souchon, Y.; Sabaton, C.; Deibel, R.; Reiser, D.; Kershner, J.; Gard, M.; Katopodis, C.; Leonard, P.; Poff, N.L.; Miller, W.J.; Lamb, B.L.

    2008-01-01

    The conclusions of numerous stream restoration assessments all around the world are extremely clear and convergent: there has been insufficient appropriate monitoring to improve general knowledge and expertise. In the specialized field of instream flow alterations, we consider that there are several opportunities comparable to full-size experiments. Hundreds of water management decisions related to instream flow releases have been made by government agencies, native peoples, and non-governmental organizations around the world. These decisions are based on different methods and assumptions and many flow regimes have been adopted by formal or informal rules and regulations. Although, there have been significant advances in analytical capabilities, there has been very little validation monitoring of actual outcomes or research related to the response of aquatic dependent species to new flow regimes. In order to be able to detect these kinds of responses and to better guide decision, a general design template is proposed. The main steps of this template are described and discussed, in terms of objectives, hypotheses, variables, time scale, data management, and information, in the spirit of adaptive management. The adoption of such a framework is not always easy, due to differing interests of actors for the results, regarding the duration of monitoring, nature of funding and differential timetables between facilities managers and technicians. Nevertheless, implementation of such a framework could help researchers and practitioners to coordinate and federate their efforts to improve the general knowledge of the links between the habitat dynamics and biological aquatic responses. Copyright ?? 2008 John Wiley & Sons, Ltd.

  1. Direct Detection Doppler Lidar for Spaceborne Wind Measurement

    NASA Technical Reports Server (NTRS)

    Korb, C. Laurence; Flesia, Cristina

    1999-01-01

    The theory of double edge lidar techniques for measuring the atmospheric wind using aerosol and molecular backscatter is described. Two high spectral resolution filters with opposite slopes are located about the laser frequency for the aerosol based measurement or in the wings of the Rayleigh - Brillouin profile for the molecular measurement. This doubles the signal change per unit Doppler shift and improves the measurement accuracy by nearly a factor of 2 relative to the single edge technique. For the aerosol based measurement, the use of two high resolution edge filters reduces the effects of background, Rayleigh scattering, by as much as an order of magnitude and substantially improves the measurement accuracy. Also, we describe a method that allows the Rayleigh and aerosol components of the signal to be independently determined. A measurement accuracy of 1.2 m/s can be obtained for a signal level of 1000 detected photons which corresponds to signal levels in the boundary layer. For the molecular based measurement, we describe the use of a crossover region where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering and greatly simplifies the measurement. Simulations using a conical scanning spaceborne lidar at 355 nm give an accuracy of 2-3 m/s for altitudes of 2-15 km for a 1 km vertical resolution, a satellite altitude of 400 km, and a 200 km x 200 km spatial.

  2. Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals.

    PubMed

    Belopolski, Ilya; Xu, Su-Yang; Sanchez, Daniel S; Chang, Guoqing; Guo, Cheng; Neupane, Madhab; Zheng, Hao; Lee, Chi-Cheng; Huang, Shin-Ming; Bian, Guang; Alidoust, Nasser; Chang, Tay-Rong; Wang, BaoKai; Zhang, Xiao; Bansil, Arun; Jeng, Horng-Tay; Lin, Hsin; Jia, Shuang; Hasan, M Zahid

    2016-02-12

    The recent discovery of the first Weyl semimetal in TaAs provides the first observation of a Weyl fermion in nature and demonstrates a novel type of anomalous surface state, the Fermi arc. Like topological insulators, the bulk topological invariants of a Weyl semimetal are uniquely fixed by the surface states of a bulk sample. Here we present a set of distinct conditions, accessible by angle-resolved photoemission spectroscopy (ARPES), each of which demonstrates topological Fermi arcs in a surface state band structure, with minimal reliance on calculation. We apply these results to TaAs and NbP. For the first time, we rigorously demonstrate a nonzero Chern number in TaAs by counting chiral edge modes on a closed loop. We further show that it is unreasonable to directly observe Fermi arcs in NbP by ARPES within available experimental resolution and spectral linewidth. Our results are general and apply to any new material to demonstrate a Weyl semimetal. PMID:26919005

  3. Learned helplessness and the detection of contingency: a direct test.

    PubMed

    Tennen, H; Drum, P E; Gillen, R; Stanton, A

    1982-12-01

    Two studies tested a basic hypothesis of the learned helplessness model: That performance deficits associated with exposure to uncontrollable outcomes are directly mediated by an individual's perception of response-outcome independence. In the first experiment 48 subjects were exposed to noise bursts. For one experimental group, the termination of the noise was response-contingent. For five other groups, noise-burst termination was independent of subjects' responses. These five groups varied in the number of trials on which they received positive feedback: As predicted, subjects over-estimated the amount of control they had over noise termination as a positive linear function of the amount of noncontingent positive feedback they received. Although subjects exposed to either noncontingent positive or negative feedback showed subsequent performance deficits on an anagrams task, the expected relation between perceived control and subsequent performance failed to emerge. These findings were replicated in a second experiment. In addition, subjects' locus, stability, and globality attributions failed to predict subsequent performance. These results call into question the central premises of helplessness theory: That perceived uncontrollability and causal attributions mediate learned helplessness.

  4. Low complexity PAPR reduction techniques for clipping and quantization noise mitigation in direct-detection O-OFDM systems

    NASA Astrophysics Data System (ADS)

    Nadal, Laia; Svaluto Moreolo, Michela; Fàbrega, Josep M.; Junyent, Gabriel

    2014-06-01

    We present different distortionless peak-to-average power ratio (PAPR) reduction techniques that can be easily applied, without any symmetry restriction, in direct-detection (DD) optical orthogonal frequency division multiplexing (O-OFDM) systems based on the fast Hartley transform (FHT). The performance of DD O-OFDM systems is limited by the constraints on system components such as digital-to-analog converter (DAC), analog-to-digital converter (ADC), the Mach-Zehnder modulator (MZM) and electrical amplifiers. In this paper, in order to relax the constraints on these components, we propose to symmetrically clip the transmitted signal and apply low complexity (LC) distortionless PAPR reduction schemes able to mitigate, at the same time, PAPR, quantization and clipping noise. We demonstrate that, applying LC-selective mapping (SLM) without any additional transform block, the PAPR reduction is 1.5dB with only one additional FHT block using LC-partial transmit sequence (PTS) with random partitions; up to 3.1dB reduction is obtained. Moreover, the sensitivity performance and the power efficiency are enhanced. In fact, applying LC PAPR reduction techniques with one additional transform block and a 6 bit DAC resolution, the required receiver power for 8 dB clipping level and for a 10-3BER is reduced by 5.1dB.

  5. Architectural constraints are a major factor reducing path integration accuracy in the rat head direction cell system.

    PubMed

    Page, Hector J I; Walters, Daniel; Stringer, Simon M

    2015-01-01

    Head direction cells fire to signal the direction in which an animal's head is pointing. They are able to track head direction using only internally-derived information (path integration)In this simulation study we investigate the factors that affect path integration accuracy. Specifically, two major limiting factors are identified: rise time, the time after stimulation it takes for a neuron to start firing, and the presence of symmetric non-offset within-layer recurrent collateral connectivity. On the basis of the latter, the important prediction is made that head direction cell regions directly involved in path integration will not contain this type of connectivity; giving a theoretical explanation for architectural observations. Increased neuronal rise time is found to slow path integration, and the slowing effect for a given rise time is found to be more severe in the context of short conduction delays. Further work is suggested on the basis of our findings, which represent a valuable contribution to understanding of the head direction cell system.

  6. The direct detection of boosted dark matter at high energies and PeV events at IceCube

    SciTech Connect

    Bhattacharya, A.; Gandhi, R.; Gupta, A.

    2015-03-13

    We study the possibility of detecting dark matter directly via a small but energetic component that is allowed within present-day constraints. Drawing closely upon the fact that neutral current neutrino nucleon interactions are indistinguishable from DM-nucleon interactions at low energies, we extend this feature to high energies for a small, non-thermal but highly energetic population of DM particle χ, created via the decay of a significantly more massive and long-lived non-thermal relic Φ, which forms the bulk of DM. If χ interacts with nucleons, its cross-section, like the neutrino-nucleus coherent cross-section, can rise sharply with energy leading to deep inelastic scattering, similar to neutral current neutrino-nucleon interactions at high energies. Thus, its direct detection may be possible via cascades in very large neutrino detectors. As a specific example, we apply this notion to the recently reported three ultra-high energy PeV cascade events clustered around 1 – 2 PeV at IceCube (IC). We discuss the features which may help discriminate this scenario from one in which only astrophysical neutrinos constitute the event sample in detectors like IC.

  7. The direct detection of boosted dark matter at high energies and PeV events at IceCube

    SciTech Connect

    Bhattacharya, A.; Gandhi, R.; Gupta, A.

    2015-03-13

    We study the possibility of detecting dark matter directly via a small but energetic component that is allowed within present-day constraints. Drawing closely upon the fact that neutral current neutrino nucleon interactions are indistinguishable from DM-nucleon interactions at low energies, we extend this feature to high energies for a small, non-thermal but highly energetic population of DM particle χ, created via the decay of a significantly more massive and long-lived non-thermal relic ϕ, which forms the bulk of DM. If χ interacts with nucleons, its cross-section, like the neutrino-nucleus coherent cross-section, can rise sharply with energy leading to deep inelastic scattering, similar to neutral current neutrino-nucleon interactions at high energies. Thus, its direct detection may be possible via cascades in very large neutrino detectors. As a specific example, we apply this notion to the recently reported three ultra-high energy PeV cascade events clustered around 1−2 PeV at IceCube (IC). We discuss the features which may help discriminate this scenario from one in which only astrophysical neutrinos constitute the event sample in detectors like IC.

  8. The direct detection of boosted dark matter at high energies and PeV events at IceCube

    DOE PAGESBeta

    Bhattacharya, A.; Gandhi, R.; Gupta, A.

    2015-03-13

    We study the possibility of detecting dark matter directly via a small but energetic component that is allowed within present-day constraints. Drawing closely upon the fact that neutral current neutrino nucleon interactions are indistinguishable from DM-nucleon interactions at low energies, we extend this feature to high energies for a small, non-thermal but highly energetic population of DM particle χ, created via the decay of a significantly more massive and long-lived non-thermal relic Φ, which forms the bulk of DM. If χ interacts with nucleons, its cross-section, like the neutrino-nucleus coherent cross-section, can rise sharply with energy leading to deep inelasticmore » scattering, similar to neutral current neutrino-nucleon interactions at high energies. Thus, its direct detection may be possible via cascades in very large neutrino detectors. As a specific example, we apply this notion to the recently reported three ultra-high energy PeV cascade events clustered around 1 – 2 PeV at IceCube (IC). We discuss the features which may help discriminate this scenario from one in which only astrophysical neutrinos constitute the event sample in detectors like IC.« less

  9. Direct detection of Mycobacterium tuberculosis complex in nonrespiratory specimens by Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test.

    PubMed Central

    Gamboa, F; Manterola, J M; Viñado, B; Matas, L; Giménez, M; Lonca, J; Manzano, J R; Rodrigo, C; Cardona, P J; Padilla, E; Domínguez, J; Ausina, V

    1997-01-01

    The Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test (AMTDT) was adapted for the detection of Mycobacterium tuberculosis complex in 224 nonrespiratory specimens from 188 patients. The sensitivity and specificity of the AMTDT for such specimens, after resolution of discrepant results, were 85.7 and 100%, respectively. Pretreatment of nonrespiratory specimens with sodium dodecyl (lauryl) sulfate is mandatory to obtain consistent and reproducible AMTDT results. The use of 500 microliters of decontaminated specimen improves the sensitivity of the test. Because the AMTDT detects stable rRNA from noncultivable bacilli, it is not useful for monitoring patients receiving treatment. PMID:8968935

  10. A review of the discovery reach of directional Dark Matter detection

    NASA Astrophysics Data System (ADS)

    Mayet, F.; Green, A. M.; Battat, J. B. R.; Billard, J.; Bozorgnia, N.; Gelmini, G. B.; Gondolo, P.; Kavanagh, B. J.; Lee, S. K.; Loomba, D.; Monroe, J.; Morgan, B.; O'Hare, C. A. J.; Peter, A. H. G.; Phan, N. S.; Vahsen, S. E.

    2016-04-01

    Cosmological observations indicate that most of the matter in the Universe is Dark Matter. Dark Matter in the form of Weakly Interacting Massive Particles (WIMPs) can be detected directly, via its elastic scattering off target nuclei. Most current direct detection experiments only measure the energy of the recoiling nuclei. However, directional detection experiments are sensitive to the direction of the nuclear recoil as well. Due to the Sun's motion with respect to the Galactic rest frame, the directional recoil rate has a dipole feature, peaking around the direction of the Solar motion. This provides a powerful tool for demonstrating the Galactic origin of nuclear recoils and hence unambiguously detecting Dark Matter. Furthermore, the directional recoil distribution depends on the WIMP mass, scattering cross section and local velocity distribution. Therefore, with a large number of recoil events it will be possible to study the physics of Dark Matter in terms of particle and astrophysical properties. We review the potential of directional detectors for detecting and characterizing WIMPs.

  11. Molecular detection of human adenovirus in sediment using a direct detection method compared to the classical polyethylene glycol precipitation.

    PubMed

    Staggemeier, Rodrigo; Bortoluzzi, Marina; da Silva Heck, Tatiana Moraes; da Silva, Tiago; Spilki, Fernando Rosado; de Matos Almeida, Sabrina Esteves

    2015-03-01

    Various effective methods have been developed to measure the concentration of viruses in sediment samples. However, there is need to standardize less laborious and simpler techniques. The objective of the present study was to compare two different methods to measure the concentration of viruses in soil samples. The use of polyethylene glycol (PEG) was compared with a direct extraction of viral nucleic acids from the samples diluted in modified Eagle's minimal essential medium (E-MEM). The presence of adenovirus in the samples was detected by real-time quantitative polymerase chain reaction (qPCR). Only six samples (30%) were positive for adenovirus when PEG technique was used. The direct method showed 16 (80%) samples positive for adenovirus. Therefore, direct detection (i.e. without previous concentration) demonstrated a higher rate of detection, better effectiveness, and shorter execution time. Furthermore, direct detection uses reagents that are often readily available in virology laboratories. Thus, it is an attractive alternative to other methods of detection of virus particles in sediments.

  12. Signal to Noise Ratios of Pulsed and Sinewave Modulated Direct Detection Lidar for IPDA Measurements

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.

    2011-01-01

    The signal-to-noise ratios have been derived for IPDA lidar using a direct detection receiver for both pulsed and sinewave laser modulation techniques, and the results and laboratory measurements are presented

  13. Direct measurement of sub-wavelength interference using thermal light and photon-number-resolved detection

    SciTech Connect

    Zhai, Yanhua E-mail: jfan@nist.gov; Fan, Jingyun E-mail: jfan@nist.gov; Migdall, Alan; Becerra, Francisco E.

    2014-09-08

    We examine thermal light diffracted through a double slit using photon-number-resolved detection to directly measure high-order spatial correlations, and we see sinusoidal modulations of those correlations. The fringe width can, in principal, be made arbitrarily small, and we have experimentally obtained fringe widths as small as 30 nm with 800 nm wavelength light. This extreme sub-wavelength resolution, along with this direct detection technique, offers potential for high precision measurement applications.

  14. Comparison of the pseudorandom noise code and pulsed direct-detection lidars for atmospheric probing.

    PubMed

    Machol, J L

    1997-08-20

    The advantages and limitations of using the pseudorandom-noise (PN)-code technique in comparison with pulsed direct detection are discussed. Because the signal-to-noise ratio (SNR) of the PN codes is dependent on the average atmospheric return, strong returns from short ranges and clouds determine the SNR for all ranges. The SNR of a profile obtained by pulsed direct detection exceeds that of the PN-code technique for laser beams with the same average power.

  15. Direct measurement of sub-wavelength interference using thermal light and photon-number-resolved detection

    NASA Astrophysics Data System (ADS)

    Zhai, Yanhua; Becerra, Francisco E.; Fan, Jingyun; Migdall, Alan

    2014-09-01

    We examine thermal light diffracted through a double slit using photon-number-resolved detection to directly measure high-order spatial correlations, and we see sinusoidal modulations of those correlations. The fringe width can, in principal, be made arbitrarily small, and we have experimentally obtained fringe widths as small as 30 nm with 800 nm wavelength light. This extreme sub-wavelength resolution, along with this direct detection technique, offers potential for high precision measurement applications.

  16. CHEMICAL ENRICHMENT OF DAMPED Ly{alpha} SYSTEMS AS A DIRECT CONSTRAINT ON POPULATION III STAR FORMATION

    SciTech Connect

    Kulkarni, Girish; Hennawi, Joseph F.; Rollinde, Emmanuel; Vangioni, Elisabeth

    2013-08-01

    . We find that these distributions are anchored toward abundance ratios set by Population II supernova yields, but they exhibit a tail which depends significantly on the Population III IMF for z > 5. Thus, a sample of DLA metallicity and relative abundance measurements at high redshift holds the promise to constrain Population III enrichment and the Population III IMF. We find that a sample of just 10 DLAs with relative abundances measured to an accuracy of 0.1 dex is sufficient to constrain the Population III IMF at 4{sigma}. These constraints may prove stronger than other probes of Population III enrichment, such as metal-poor stars and individual metal-poor DLAs. Our results provide a global picture of the thermal, ionization, and chemical evolution of the universe, and have the potential to rule out certain Population III scenarios.

  17. Direct fluorescent antibody technique for the detection of bacterial kidney disease in paraffin-embedded tissues

    USGS Publications Warehouse

    Ochiai, T.; Yasutake, W.T.; Gould, R.W.

    1985-01-01

    The direct fluorescent antibody technique (FAT) was successfully used to detect the causative agent of bacterial kidney disease (BKD), Renibacterium salmoninarum, in Bouin's solution flexed and paraffinembedded egg and tissue sections. This method is superior to gram stain and may be particularly useful in detecting the BKD organism in fish with low-grade infection.

  18. Evaluation of harmonic direction-finding systems for detecting locomotor activity

    USGS Publications Warehouse

    Boyarski, V.L.; Rodda, G.H.; Savidge, J.A.

    2007-01-01

    We conducted a physical simulation experiment to test the efficacy of harmonic direction finding for remotely detecting locomotor activity in animals. The ability to remotely detect movement helps to avoid disturbing natural movement behavior. Remote detection implies that the observer can sense only a change in signal bearing. In our simulated movements, small changes in bearing (<5.7??) were routinely undetectable. Detectability improved progressively with the size of the simulated animal movement. The average (??SD) of reflector tag movements correctly detected for 5 observers was 93.9 ?? 12.8% when the tag was moved ???11.5??; most observers correctly detected tag movements ???20.1??. Given our data, one can assess whether the technique will be effective for detecting movements at an observation distance appropriate for the study organism. We recommend that both habitat and behavior of the organism be taken into consideration when contemplating use of this technique for detecting locomotion.

  19. Is Anyone Looking at Me? Direct Gaze Detection in Children with and without Autism

    ERIC Educational Resources Information Center

    Senju, Atsushi; Kikuchi, Yukiko; Hasegawa, Toshikazu; Tojo, Yoshikuni; Osanai, Hiroo

    2008-01-01

    Atypical processing of eye contact is one of the significant characteristics of individuals with autism, but the mechanism underlying atypical direct gaze processing is still unclear. This study used a visual search paradigm to examine whether the facial context would affect direct gaze detection in children with autism. Participants were asked to…

  20. PREFACE: CYGNUS 2013: 4th Workshop on Directional Detection of Dark Matter

    NASA Astrophysics Data System (ADS)

    Naka, Tatsuhiro; Miuchi, Kentaro

    2013-12-01

    It is a great pleasure to publish the proceedings of the 4th Workshop on Directional Detection of Dark Matter held in Toyama, Japan on 10-12 June 2013 (CYGNUS 2013). These proceedings contain written versions of the presentations made at CYGNUS 2013 as scientific outputs of the directional detection of dark matter. The GYGNUS workshop started in 2007 at Boulby Underground Laboratory (UK), followed by CYGNUS 2009 (MIT in Cambridge, Massachusetts, USA) and CYGNUS 2011 (AUSSOIS, France). CYGNUS 2013 was held by the combination of a two and a half days of scientific program and a half day visit to the underground laboratory (Kamioka Observatory) as a 'tradition' of CYGNUS workshops. The name 'CYGNUS' came from the fact that the 'dark matter wind' is expected to come from the direction of the constellation Cygnus due to the motion of the Solar system in the galaxy. A general aim of these CYGNUS workshops is to bring together the theoretical and experimental studies on the directional dark matter detection. Directional detection of dark matter is a promising approach to a 'clear detection' and also to 'further investigations' of galactic dark matter, or Weakly Interacting Massive Particles (WIMPs). Directional detection requires the simultaneous detection of the energy and track of low energy recoils. Among many technological challenges for the requirement above, three of them, namely size, background, and directionality (angular resolution and head-tail detection), are most important to demonstrate and improve the quality as a dark matter detector. In the workshop, up-to-date activities by the international reserchers are discussed. The workshop was a great success thanks to the oral contributions and fruitful discussions held throughout the workshop period. We hope that readers will remember and share the great enthusiasm shown during the CYGNUS 2013 workshop. The Editors Tatsuhiro Naka and Kentaro Miuchi

  1. Combining parallel detection of proton echo planar spectroscopic imaging (PEPSI) measurements with a data-consistency constraint improves SNR.

    PubMed

    Tsai, Shang-Yueh; Hsu, Yi-Cheng; Chu, Ying-Hua; Kuo, Wen-Jui; Lin, Fa-Hsuan

    2015-12-01

    One major challenge of MRSI is the poor signal-to-noise ratio (SNR), which can be improved by using a surface coil array. Here we propose to exploit the spatial sensitivity of different channels of a coil array to enforce the k-space data consistency (DC) in order to suppress noise and consequently to improve MRSI SNR. MRSI data were collected using a proton echo planar spectroscopic imaging (PEPSI) sequence at 3 T using a 32-channel coil array and were averaged with one, two and eight measurements (avg-1, avg-2 and avg-8). The DC constraint was applied using a regularization parameter λ of 1, 2, 3, 5 or 10. Metabolite concentrations were quantified using LCModel. Our results show that the suppression of noise by applying the DC constraint to PEPSI reconstruction yields up to 32% and 27% SNR gain for avg-1 and avg-2 data with λ = 5, respectively. According to the reported Cramer-Rao lower bounds, the improvement in metabolic fitting was significant (p < 0.01) when the DC constraint was applied with λ ≥ 2. Using the DC constraint with λ = 3 or 5 can minimize both root-mean-square errors and spatial variation for all subjects using the avg-8 data set as reference values. Our results suggest that MRSI reconstructed with a DC constraint can save around 70% of scanning time to obtain images and spectra with similar SNRs using λ = 5.

  2. Combining parallel detection of proton echo planar spectroscopic imaging (PEPSI) measurements with a data-consistency constraint improves SNR.

    PubMed

    Tsai, Shang-Yueh; Hsu, Yi-Cheng; Chu, Ying-Hua; Kuo, Wen-Jui; Lin, Fa-Hsuan

    2015-12-01

    One major challenge of MRSI is the poor signal-to-noise ratio (SNR), which can be improved by using a surface coil array. Here we propose to exploit the spatial sensitivity of different channels of a coil array to enforce the k-space data consistency (DC) in order to suppress noise and consequently to improve MRSI SNR. MRSI data were collected using a proton echo planar spectroscopic imaging (PEPSI) sequence at 3 T using a 32-channel coil array and were averaged with one, two and eight measurements (avg-1, avg-2 and avg-8). The DC constraint was applied using a regularization parameter λ of 1, 2, 3, 5 or 10. Metabolite concentrations were quantified using LCModel. Our results show that the suppression of noise by applying the DC constraint to PEPSI reconstruction yields up to 32% and 27% SNR gain for avg-1 and avg-2 data with λ = 5, respectively. According to the reported Cramer-Rao lower bounds, the improvement in metabolic fitting was significant (p < 0.01) when the DC constraint was applied with λ ≥ 2. Using the DC constraint with λ = 3 or 5 can minimize both root-mean-square errors and spatial variation for all subjects using the avg-8 data set as reference values. Our results suggest that MRSI reconstructed with a DC constraint can save around 70% of scanning time to obtain images and spectra with similar SNRs using λ = 5. PMID:26484749

  3. Direct detection of 16S rRNA in soil extracts by using oligonucleotide microarrays.

    PubMed

    Small, J; Call, D R; Brockman, F J; Straub, T M; Chandler, D P

    2001-10-01

    We report on the development and validation of a simple microarray method for the direct detection of intact 16S rRNA from unpurified soil extracts. Total RNAs from Geobacter chapellei and Desulfovibrio desulfuricans were hybridized to an oligonucleotide array consisting of universal and species-specific 16S rRNA probes. PCR-amplified products from Geobacter and Desulfovibrio were easily and specifically detected under a range of hybridization times, temperatures, and buffers. However, reproducible, specific hybridization and detection of intact rRNA could be accomplished only by using a chaperone-detector probe strategy. With this knowledge, assay conditions were developed for rRNA detection using a 2-h hybridization time at room temperature. Hybridization specificity and signal intensity were enhanced using fragmented RNA. Formamide was required in the hybridization buffer in order to achieve species-specific detection of intact rRNA. With the chaperone detection strategy, we were able to specifically hybridize and detect G. chapellei 16S rRNA directly from a total-RNA soil extract, without further purification or removal of soluble soil constituents. The detection sensitivity for G. chapellei 16S rRNA in soil extracts was at least 0.5 microg of total RNA, representing approximately 7.5 x 10(6) Geobacter cell equivalents of RNA. These results suggest that it is now possible to apply microarray technology to the direct detection of microorganisms in environmental samples, without using PCR. PMID:11571176

  4. Network community structure detection for directional neural networks inferred from multichannel multisubject EEG data.

    PubMed

    Liu, Ying; Moser, Jason; Aviyente, Selin

    2014-07-01

    In many neuroscience applications, one is interested in identifying the functional brain modules from multichannel, multiple subject neuroimaging data. However, most of the existing network community structure detection algorithms are limited to single undirected networks and cannot reveal the common community structure for a collection of directed networks. In this paper, we propose a community detection algorithm for weighted asymmetric (directed) networks representing the effective connectivity in the brain. Moreover, the issue of finding a common community structure across subjects is addressed by maximizing the total modularity of the group. Finally, the proposed community detection algorithm is applied to multichannel multisubject electroencephalogram data.

  5. Searching for Dark Matter in Unification Models: A Hint from Indirect Sensitivities towards Future Signals in Direct Detection and B-decays

    SciTech Connect

    Olive, Keith A.

    2006-11-28

    A comparison is made between accelerator and direct detection constraints in constrained versions of the minimal supersymmetric standard model. Models considered are based on mSUGRA, where scalar and gaugino masses are unified at the GUT scale. In addition, the mSUGRA relation between the (unified) A and B parameters is assumed, as is the relation between m0 and gravitino mass. Also considered are models where the latter two conditions are dropped (the CMSSM), and a less constrained version where the Higgs soft masses are not unified at the GUT scale (the NUHM)

  6. Receiver Signal to Noise Ratios for IPDA Lidars Using Sine-wave and Pulsed Laser Modulation and Direct Detections

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Abshire, James B.

    2011-01-01

    Integrated path differential absorption (IPDA) lidar can be used to remotely measure the column density of gases in the path to a scattering target [1]. The total column gas molecular density can be derived from the ratio of the laser echo signal power with the laser wavelength on the gas absorption line (on-line) to that off the line (off-line). 80th coherent detection and direct detection IPDA lidar have been used successfully in the past in horizontal path and airborne remote sensing measurements. However, for space based measurements, the signal propagation losses are often orders of magnitude higher and it is important to use the most efficient laser modulation and detection technique to minimize the average laser power and the electrical power from the spacecraft. This paper gives an analysis the receiver signal to noise ratio (SNR) of several laser modulation and detection techniques versus the average received laser power under similar operation environments. Coherent detection [2] can give the best receiver performance when the local oscillator laser is relatively strong and the heterodyne mixing losses are negligible. Coherent detection has a high signal gain and a very narrow bandwidth for the background light and detector dark noise. However, coherent detection must maintain a high degree of coherence between the local oscillator laser and the received signal in both temporal and spatial modes. This often results in a high system complexity and low overall measurement efficiency. For measurements through atmosphere the coherence diameter of the received signal also limits the useful size of the receiver telescope. Direct detection IPDA lidars are simpler to build and have fewer constraints on the transmitter and receiver components. They can use much larger size 'photon-bucket' type telescopes to reduce the demands on the laser transmitter. Here we consider the two most widely used direct detection IPDA lidar techniques. The first technique uses two CW

  7. Characterising dark matter searches at colliders and direct detection experiments: vector mediators

    NASA Astrophysics Data System (ADS)

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-01

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: m DM , M med , g DM and g q, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. Finally, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.

  8. Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

    SciTech Connect

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-09

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: mDM, Mmed , gDM and gq, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. In conclusion, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.

  9. Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

    DOE PAGESBeta

    Buchmueller, Oliver; Dolan, Matthew J.; Malik, Sarah A.; McCabe, Christopher

    2015-01-09

    We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: mDM, Mmed , gDM and gq, the DM and mediator masses, and the mediator couplings to DM and quarks respectively. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establishmore » an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (≲5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. In conclusion, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.« less

  10. Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements

    NASA Technical Reports Server (NTRS)

    Menyuk, N.; Killinger, D. K.; Menyuk, C. R.

    1983-01-01

    The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.

  11. Direct Detection Phenomenology in Models Where the Products of Dark Matter Annihilation Interact with Nuclei.

    PubMed

    Cherry, John F; Frandsen, Mads T; Shoemaker, Ian M

    2015-06-12

    We investigate the direct detection phenomenology of a class of dark matter (DM) models in which DM does not directly interact with nuclei, but rather, the products of its annihilation do. When these annihilation products are very light compared to the DM mass, the scattering in direct detection experiments is controlled by relativistic kinematics. This results in a distinctive recoil spectrum, a nonstandard and/or even absent annual modulation, and the ability to probe DM masses as low as a ∼10  MeV. We use current LUX data to show that experimental sensitivity to thermal relic annihilation cross sections has already been reached in a class of models. Moreover, the compatibility of dark matter direct detection experiments can be compared directly in Emin space without making assumptions about DM astrophysics, mass, or scattering form factors. Lastly, when DM has direct couplings to nuclei, the limit from annihilation to relativistic particles in the Sun can be stronger than that of conventional nonrelativistic direct detection by more than 3 orders of magnitude for masses in a 2-7 GeV window.

  12. Excluding the light dark matter window of a 331 model using LHC and direct dark matter detection data

    SciTech Connect

    Cogollo, D.; Gonzalez-Morales, Alma X.; Queiroz, Farinaldo S.; Teles, P. Rebello E-mail: alxogonz@ucsc.edu E-mail: patricia.rebello.teles@cern.ch

    2014-11-01

    We sift the impact of the recent Higgs precise measurements, and recent dark matter direct detection results, on the dark sector of an electroweak extension of the Standard Model that has a complex scalar as dark matter. We find that in this model the Higgs decays with a large branching ratio into dark matter particles, and charged scalars when these are kinematically available, for any coupling strength differently from the so called Higgs portal. Moreover, we compute the abundance and spin-independent WIMP-nucleon scattering cross section, which are driven by the Higgs and Z{sup '} boson processes. We decisively exclude the 1–500 GeV dark matter window and find the most stringent lower bound in the literature on the scale of symmetry breaking of the model namely 10 TeV, after applying the LUX-2013 limit. Interestingly, the projected XENON1T constraint will be able to rule out the entire 1 GeV–1000 GeV dark matter mass range. Lastly, for completeness, we compute the charged scalar production cross section at the LHC and comment on the possibility of detection at current and future LHC runnings.

  13. Advancing Solar Irradiance Measurement for Climate-Related Studies: Accurate Constraint on Direct Aerosol Radiative Effect (DARE)

    NASA Technical Reports Server (NTRS)

    Tsay, Si-Chee; Ji, Q. Jack

    2011-01-01

    Earth's climate is driven primarily by solar radiation. As summarized in various IPCC reports, the global average of radiative forcing for different agents and mechanisms, such as aerosols or CO2 doubling, is in the range of a few W/sq m. However, when solar irradiance is measured by broadband radiometers, such as the fleet of Eppley Precision Solar Pyranometers (PSP) and equivalent instrumentation employed worldwide, the measurement uncertainty is larger than 2% (e.g., WMO specification of pyranometer, 2008). Thus, out of the approx. 184 W/sq m (approx.263 W/sq m if cloud-free) surface solar insolation (Trenberth et al. 2009), the measurement uncertainty is greater than +/-3.6 W/sq m, overwhelming the climate change signals. To discern these signals, less than a 1 % measurement uncertainty is required and is currently achievable only by means of a newly developed methodology employing a modified PSP-like pyranometer and an updated calibration equation to account for its thermal effects (li and Tsay, 2010). In this talk, we will show that some auxiliary measurements, such as those from a collocated pyrgeometer or air temperature sensors, can help correct historical datasets. Additionally, we will also demonstrate that a pyrheliometer is not free of the thermal effect; therefore, comparing to a high cost yet still not thermal-effect-free "direct + diffuse" approach in measuring surface solar irradiance, our new method is more economical, and more likely to be suitable for correcting a wide variety of historical datasets. Modeling simulations will be presented that a corrected solar irradiance measurement has a significant impact on aerosol forcing, and thus plays an important role in climate studies.

  14. Infrared adaptive spectral imagers for direct detection of spectral signatures and hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Goldstein, Neil; Fox, Marsha; Adler-Golden, Steven; Gregor, Brian

    2013-03-01

    Field test results are presented for a prototype long-wave adaptive imager that provides both hyperspectral imagery and contrast imagery based on the direct application of hyperspectral detection algorithms in hardware. Programmable spatial light modulators are used to provide both spectral and spatial resolution using a single element detector. Programmable spectral and spatial detection filters can be used to superimpose any possible analog spectral detection filter on the image. In this work, we demonstrate three modes of operation, including hyperspectral imagery, and one and two-dimensional imagery using a generalized matched filter for detection of a specific target gas within the scene.

  15. How to calculate dark matter direct detection exclusion limits that are consistent with gamma rays from annihilation in the Milky Way halo

    NASA Astrophysics Data System (ADS)

    Cerdeño, David G.; Fornasa, Mattia; Green, Anne M.; Peiró, Miguel

    2016-08-01

    When comparing constraints on the weakly interacting massive particle (WIMP) properties from direct and indirect detection experiments it is crucial that the assumptions made about the dark matter (DM) distribution are realistic and consistent. For instance, if the Fermi-LAT Galactic center GeV gamma-ray excess was due to WIMP annihilation, its morphology would be incompatible with the standard halo model that is usually used to interpret data from direct detection experiments. In this article, we calculate exclusion limits from direct detection experiments using self-consistent velocity distributions, derived from mass models of the Milky Way where the DM halo has a generalized Navarro-Frenk-White profile. We use two different methods to make the mass model compatible with a DM interpretation of the Galactic center gamma-ray excess. First, we fix the inner slope of the DM density profile to the value that best fits the morphology of the excess. Second, we allow the inner slope to vary and include the morphology of the excess in the data sets used to constrain the gravitational potential of the Milky Way. The resulting direct detection limits differ significantly from those derived using the standard halo model, in particular for light WIMPs, due to the differences in both the local DM density and velocity distribution.

  16. A comparison of directed search target detection versus in-scene target detection in Worldview-2 datasets

    NASA Astrophysics Data System (ADS)

    Grossman, S.

    2015-05-01

    Since the events of September 11, 2001, the intelligence focus has moved from large order-of-battle targets to small targets of opportunity. Additionally, the business community has discovered the use of remotely sensed data to anticipate demand and derive data on their competition. This requires the finer spectral and spatial fidelity now available to recognize those targets. This work hypothesizes that directed searches using calibrated data perform at least as well as inscene manually intensive target detection searches. It uses calibrated Worldview-2 multispectral images with NEF generated signatures and standard detection algorithms to compare bespoke directed search capabilities against ENVI™ in-scene search capabilities. Multiple execution runs are performed at increasing thresholds to generate detection rates. These rates are plotted and statistically analyzed. While individual head-to-head comparison results vary, 88% of the directed searches performed at least as well as in-scene searches with 50% clearly outperforming in-scene methods. The results strongly support the premise that directed searches perform at least as well as comparable in-scene searches.

  17. Magnetically trigged direct electrochemical detection of DNA hybridization using Au67 quantum dot as electrical tracer.

    PubMed

    Pumera, Martin; Castañeda, Maria Teresa; Pividori, Maria Isabel; Eritja, Ramon; Merkoçi, Arben; Alegret, Salvador

    2005-10-11

    A novel gold nanoparticle-based protocol for detection of DNA hybridization based on a magnetically trigged direct electrochemical detection of gold quantum dot tracers is described. It relies on binding target DNA (here called DNA1) with Au(67) quantum dot in a ratio 1:1, followed by a genomagnetic hybridization assay between Au(67)-DNA1 and complementary probe DNA (here called DNA2) marked paramagnetic beads. Differential pulse voltammetry is used for a direct voltammetric detection of resulting Au(67) quantum dot-DNA1/DNA2-paramagnetic bead conjugate on magnetic graphite-epoxy composite electrode. The characterization, optimization, and advantages of the direct electrochemical detection assay for target DNA are demonstrated. The two main highlights of presented assay are (1) the direct voltammetric detection of metal quantum dots obviates their chemical dissolution and (2) the Au(67) quantum dot-DNA1/DNA2-paramagnetic bead conjugate does not create the interconnected three-dimensional network of Au-DNA duplex-paramagnetic beads as previously developed nanoparticle DNA assays, pushing down the achievable detection limits.

  18. Detection of Mycobacterium avium subsp. paratuberculosis by a Direct In Situ PCR Method

    PubMed Central

    Delgado, Fernando; Aguilar, Diana; Garbaccio, Sergio; Francinelli, Gladys; Hernández-Pando, R.; Romano, María Isabel

    2011-01-01

    In situ detection of Mycobacterium avium subsp. paratuberculosis is useful for diagnosis and research of paratuberculosis. The aim of this paper was to detect this agent in formalin-fixed, paraffin-embedded tissue samples by a direct in situ PCR. The technique was performed on ileum or ileocaecal lymph node samples from 8 naturally infected cattle and 1 healthy calf, by using p89 and p92 primers for amplification of IS900 sequence. Moderate positive signal was detected in all positive samples and not in negative control, but tissues resulted were affected in many cases due to the enzymatic treatment and the high temperature exposition. Although the technique was useful for Map detection, the signal was lower than immunohistochemistry probably because of the fixation process. In one case, signal was higher, which might be due to the detection of spheroplasts. Thus, the described method should be recommended when others resulted negative or for spheroplasts detection. PMID:21772965

  19. Halo-independent direct detection of momentum-dependent dark matter

    SciTech Connect

    Cherry, John F.; Frandsen, Mads T.; Shoemaker, Ian M. E-mail: frandsen@cp3-origins.net

    2014-10-01

    We show that the momentum dependence of dark matter interactions with nuclei can be probed in direct detection experiments without knowledge of the dark matter velocity distribution. This is one of the few properties of DM microphysics that can be determined with direct detection alone, given a signal of dark matter in multiple direct detection experiments with different targets. Long-range interactions arising from the exchange of a light mediator are one example of momentum-dependent DM. For data produced from the exchange of a massless mediator we find for example that the mediator mass can be constrained to be ∼< 10 MeV for DM in the 20-1000 GeV range in a halo-independent manner.

  20. Thin silicon strip devices for direct electron detection in transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Moldovan, Grigore; Li, Xiaobing; Wilshaw, Peter; Kirkland, Angus

    2008-06-01

    Indirect imaging detection systems used in transmission electron microscopy (TEM) impose a range of restrictions limiting performance that can be easily surpassed with direct sensing devices. A set of generic requirements is presented here first, illustrating the present detection needs and setting the context for further development in electron detection at TEM energy range. The use of directly exposed Si strip detectors in TEM is then investigated by means of Monte Carlo simulation of the electron-sensor interaction, showing that a sensitive layer with a thickness in the range of 50 μm is needed to achieve satisfactory efficiency. The results obtained here strongly indicate that improved performance would be achieved by replacing current indirect imaging systems with directly exposed thin Si strip detectors.

  1. Migratory birds use head scans to detect the direction of the earth's magnetic field.

    PubMed

    Mouritsen, Henrik; Feenders, Gesa; Liedvogel, Miriam; Kropp, Wiebke

    2004-11-01

    Night-migratory songbirds are known to use a magnetic compass , but how do they detect the reference direction provided by the geomagnetic field, and where is the sensory organ located? The most prominent characteristic of geomagnetic sensory input, whether based on visual patterns or magnetite-mediated forces , is the predicted symmetry around the north-south or east-west magnetic axis. Here, we show that caged migratory garden warblers perform head-scanning behavior well suited to detect this magnetic symmetry plane. In the natural geomagnetic field, birds move toward their migratory direction after head scanning. In a zero-magnetic field , where no symmetry plane exists, the birds almost triple their head-scanning frequency, and the movement direction after a head scan becomes random. Thus, the magnetic sensory organ is located in the bird's head, and head scans are used to locate the reference direction provided by the geomagnetic field. PMID:15530397

  2. Directed Design of Experiments (DOE) for Determining Probability of Detection (POD) Capability of NDE Systems (DOEPOD)

    NASA Technical Reports Server (NTRS)

    Generazio, Ed

    2007-01-01

    This viewgraph presentation reviews some of the issues that people who specialize in Non destructive evaluation (NDE) have with determining the statistics of the probability of detection. There is discussion of the use of the binominal distribution, and the probability of hit. The presentation then reviews the concepts of Directed Design of Experiments for Validating Probability of Detection of Inspection Systems (DOEPOD). Several cases are reviewed, and discussed. The concept of false calls is also reviewed.

  3. Robust defect detection in plain and twill fabric using directional Bollinger bands

    NASA Astrophysics Data System (ADS)

    Ngan, Henry Y. T.; Pang, Grantham K. H.

    2015-07-01

    A directional Bollinger bands (BB) method for the detection of defects in plain and twill fabric is presented, whereas a previous BB method was for patterned Jacquard fabric. BB are constructed using the moving average and standard deviation to characterize any irregularities (i.e., defects) in a patterned texture. Every patterned texture constitutes a primitive unit that can be used to generate the texture by a translational rule. The regularity property for a patterned texture can be implicitly regarded as the periodic signals on the rows and columns of an image. To utilize such a regularity property, an embedded shift-invariant characteristic of BB is explored. The original BB method is further developed using directional rotation iterations, which enables the detection of directional defects in plain and twill fabric. The directional BB method is an efficient, fast, and shift-invariant approach that enables defective regions to be clearly outlined. This approach is also immune to the alignment problem that often arises in the original method. The detection accuracies for 77 defective images and 100 defect-free images are 96.1% and 96%, respectively. In a pixel-to-pixel evaluation comparing the detection results of the defective images with the ground-truth images, a 93.51% detection success rate is achieved.

  4. Intensity modulation and direct detection quantum key distribution based on quantum noise

    NASA Astrophysics Data System (ADS)

    Ikuta, Takuya; Inoue, Kyo

    2016-01-01

    Quantum key distribution (QKD) has been studied for achieving perfectly secure cryptography based on quantum mechanics. This paper presents a novel QKD scheme that is based on an intensity-modulation and direct-detection system. Two slightly intensity-modulated pulses are sent from a transmitter, and a receiver determines key bits from the directly detected intensity. We analyzed the system performance for two typical eavesdropping methods, a beam splitting attack and an intercept-resend attack, with an assumption that the transmitting and receiving devices are fully trusted. Our brief analysis showed that short- or middle-range QKD systems are achievable with a simple setup.

  5. Development of an ion attachment mass spectrometer for direct detection of intermediates in combustion flames.

    PubMed

    Torii, Takahiro; Nishimura, Takashi; Nakamura, Megumi; Shiokawa, Yoshiro; Matsumoto, Kozo; Kitagawa, Kuniyuki

    2008-11-01

    A system with Li+ ion attachment (IA) ionization has been developed for the direct detection of intermediates formed in burning flames by mass spectrometry. Dimethyl ether (DME) among alternative fuels was selected as a test substance to examine the capability of the system. As a result, intermediates generated in a premixed DME-air flame were directly detectable as Li+ adduct ions. By moving the burner on an X-Y stage, spatial distribution profiles of different species, including unburned DME and formaldehyde, were obtained for three types of flames: diffusion, partially premixed, and premixed.

  6. Study of dual-polarization OQAM-OFDM PON with direct detection

    NASA Astrophysics Data System (ADS)

    Luo, Qing-long; Feng, Min; Bai, Cheng-lin; Hu, Wei-sheng

    2016-01-01

    An offset quadrature amplitude modulation orthogonal frequency-division multiplexing (OQAM-OFDM) passive optical network (PON) architecture with direct detection is brought up to increase the transmission range and improve the system performance. In optical line terminal (OLT), OQAM-OFDM signals at 40 Gbit/s are transmitted as downstream. At each optical network unit (ONU), the optical OQAM-OFDM signal is demodulated with direct detection. The results show that the transmission distance can exceed 20 km with negligible penalty under the experimental conditions.

  7. A SETI metapolicy: New directions towards comprehensive policies concerning the detection of extraterrestrial intelligence

    NASA Astrophysics Data System (ADS)

    Baxter, Stephen; Elliott, John

    2012-09-01

    At present we have only one agreed public policy for handling the detection of an extraterrestrial intelligence (ETI), the 'First SETI Protocol' of 1989, which guides action in the immediate aftermath of detection, even though SETI (the Search for Extraterrestrial Intelligence) constitutes an active search for such a detection. The purpose of this paper is to set out areas in which policies might fruitfully be developed, including reviewing the rationale and investment in SETI, handling ETI artefacts, and approaches to direct contact. 'Negative' possibilities will be examined, for example, whether an ETI artefact or data should be purposefully destroyed.

  8. Observations and modelling of CO and [C i] in protoplanetary disks. First detections of [C i] and constraints on the carbon abundance

    NASA Astrophysics Data System (ADS)

    Kama, M.; Bruderer, S.; Carney, M.; Hogerheijde, M.; van Dishoeck, E. F.; Fedele, D.; Baryshev, A.; Boland, W.; Güsten, R.; Aikutalp, A.; Choi, Y.; Endo, A.; Frieswijk, W.; Karska, A.; Klaassen, P.; Koumpia, E.; Kristensen, L.; Leurini, S.; Nagy, Z.; Perez Beaupuits, J.-P.; Risacher, C.; van der Marel, N.; van Kempen, T. A.; van Weeren, R. J.; Wyrowski, F.; Yıldız, U. A.

    2016-04-01

    Context. The gas-solid budget of carbon in protoplanetary disks is related to the composition of the cores and atmospheres of the planets forming in them. The principal gas-phase carbon carriers CO, C0, and C+ can now be observed regularly in disks. Aims: The gas-phase carbon abundance in disks has thus far not been well characterized observationally. We obtain new constraints on the [C]/[H] ratio in a large sample of disks, and compile an overview of the strength of [C i] and warm CO emission. Methods: We carried out a survey of the CO 6-5 line and the [C i] 1-0 and 2-1 lines towards 37 disks with the APEX telescope, and supplemented it with [C ii] data from the literature. The data are interpreted using a grid of models produced with the DALI disk code. We also investigate how well the gas-phase carbon abundance can be determined in light of parameter uncertainties. Results: The CO 6-5 line is detected in 13 out of 33 sources, [C i] 1-0 in 6 out of 12, and [C i] 2-1 in 1 out of 33. With separate deep integrations, the first unambiguous detections of the [C i] 1-0 line in disks are obtained, in TW Hya and HD 100546. Conclusions: Gas-phase carbon abundance reductions of a factor of 5-10 or more can be identified robustly based on CO and [C i] detections, assuming reasonable constraints on other parameters. The atomic carbon detection towards TW Hya confirms a factor of 100 reduction of [C]/[H]gas in that disk, while the data are consistent with an ISM-like carbon abundance for HD 100546. In addition, BP Tau, T Cha, HD 139614, HD 141569, and HD 100453 are either carbon-depleted or gas-poor disks. The low [C i] 2-1 detection rates in the survey mostly reflect insufficient sensitivity for T Tauri disks. The Herbig Ae/Be disks with CO and [C ii] upper limits below the models are debris-disk-like systems. An increase in sensitivity of roughly order of magnitude compared to our survey is required to obtain useful constraints on the gas-phase [C]/[H] ratio in most of the

  9. Aptamer-based electrochemical detection of picomolar platelet-derived growth factor directly in blood serum.

    PubMed

    Lai, Rebecca Y; Plaxco, Kevin W; Heeger, Alan J

    2007-01-01

    We report an electrochemical, aptamer-based (E-AB) sensor for the detection of platelet-derived growth factor (PDGF) directly in blood serum. The E-AB approach employs alternating current voltammetry to monitor target-induced folding in a methylene blue-modified, PDGF-binding aptamer. The sensor is sensitive, highly selective, and essentially reagentless: we readily detect the BB variant of PDGF at 1 nM directly in undiluted, unmodified blood serum and at 50 pM (1.25 ng/mL) in serum-diluted 2-fold with aqueous buffer. The sensitivity and selectivity achieved by this sensor match or significantly exceed those of the best analogous optical approaches. For example, the detection limit attained in 50% serum is achieved against a >25 million-fold excess of contaminating blood proteins and represents a 4 order of magnitude improvement over the most sensitive optical PDGF aptasensor reported to date. Moreover, the E-AB sensor combines these promising attributes in a platform that is reusable, label-free, and electronic. Given these advantages, E-AB sensors appear well suited for implementation in portable microdevices directed at the direct detection of proteins and small molecules in complex, largely unprocessed clinical samples.

  10. Fabry-Perot etalon aperture requirements for direct detection Doppler wind lidar from Earth orbit.

    PubMed

    McKay, J A

    1999-09-20

    The design of Fabry-Perot etalons for direct detection Doppler wind lidar from a satellite is considered for two direct detection methods, fringe imaging (multichannel) and double edge. The area solid-angle product of the etalon for each technique is derived and shown to be inherently larger, for a given etalon aperture, for the fringe imager than for the double-edge Doppler analyzer. Modeling of the Doppler measurement accuracy of a spaceflight direct detection wind lidar shows that a very large optical aperture, 2 m or more, is necessary. Optical throughput matching to a 2-m collector requires, for the fringe-imaging Doppler analyzer, an etalon with 60 mm aperture, whereas the double-edge technique would require two etalons of 200 mm aperture, or a split-aperture etalon of 400 mm working aperture. Because the two direct detection methods have been shown to have practically identical intrinsic sensitivities (measurement accuracies per unit signal), this difference in etalon dimensions may be a significant selection consideration. PMID:18324101

  11. Direct and fast detection of Alexandrium minutum algae by using high frequency microbalance.

    PubMed

    Sousa, Célia; Compère, Chantal; Dreanno, Catherine; Crassous, Marie-Pierre; Gas, Fabienne; Baus, Beatrice; Perrot, Hubert

    2014-09-01

    In this paper, a simple detection of a toxic algae, Alexandrium minutum, was developed using highly sensitive quartz crystal microbalance. In terms of performance, compared with other conventional analytical tools, the main interest of our immunosensor is based on a fast and direct detection of these living cells. This system requires the use of one monoclonal antibody directed against the surface antigen of A. minutum. We demonstrate that the whole living and motile algae are caught and detected. The high specificity of the biosensor is also demonstrated by testing several other dinoflagellate species. The frequency shift is correlated to the A. minutum cell concentration. This simple system is potentially promising for environmental monitoring purposes. PMID:24927989

  12. Hybrid receiver system for single photon sensitive direct and coherent detection

    NASA Astrophysics Data System (ADS)

    Kondratko, Piotr K.; Bratcher, Andrew; Glennon, John; Suni, Paul

    2015-05-01

    Hybrid receivers that enable switching between direct and coherent detection provide many imaging functions beneficial to scientific and defense applications. A hybrid receiver system is presented wherein a single detector is switched between the Geiger-mode and linear amplification modes of operation. This system benefits from enhanced functionality and lower size, weight, power, cost, and complexity compared with dual receiver implementations. The hybrid receiver sensing modality is reconfigurable on-the-fly between single photon direct detection and amplitude/phase coherent detection. The reconfiguration is achieved by adjusting detector bias (electrically) and by simultaneously enabling or disabling the local oscillator (optically). This work describes these two sensing scenarios, discusses the operation of the receiver system and shows laboratory-scale imaging results for each mode of hybrid receiver operation.

  13. CAN IBEX DETECT INTERSTELLAR NEUTRAL HELIUM OR OXYGEN FROM ANTI-RAM DIRECTIONS?

    SciTech Connect

    Galli, A.; Wurz, P.; Park, J.; Kucharek, H.; Möbius, E.; Schwadron, N. A.; Sokół, J. M.; Bzowski, M.; Kubiak, M. A.; Swaczyna, P.; Fuselier, S. A.; McComas, D. J.

    2015-10-15

    To better constrain the parameters of the interstellar neutral flow, we searched the Interstellar Boundary EXplorer (IBEX)-Lo database for helium and oxygen from the interstellar medium in the anti-ram direction in the three years (2009–2011) with the lowest background rates. We found that IBEX-Lo cannot observe interstellar helium from the anti-ram direction because the helium energy is too low for indirect detection by sputtering off the IBEX-Lo conversion surface. Our results show that this sputtering process has a low energy threshold between 25 and 30 eV, whereas the energy of the incident helium is only 10 eV for these observations. Interstellar oxygen, on the other hand, could in principle be detected in the anti-ram hemisphere, but the expected magnitude of the signal is close to the detection limit imposed by counting statistics and by the magnetospheric foreground.

  14. Energy dependence of direct detection cross section for asymmetric mirror dark matter

    SciTech Connect

    An Haipeng; Chen Shaolong; Mohapatra, Rabindra N.; Nussinov, Shmuel; Zhang Yue

    2010-07-15

    In a recent paper, four of the present authors proposed a class of dark matter models where generalized parity symmetry leads to equality of dark matter abundance with baryon asymmetry of the Universe and predicts dark matter mass to be around 5 GeV. In this paper, we explore how this model can be tested in direct search experiments. In particular, we point out that if the dark matter happens to be the mirror neutron, the direct detection cross section has the unique feature that it increases at low recoil energy unlike the case of conventional weakly interacting massive particles. It is also interesting to note that the predicted spin-dependent scattering could make significant contribution to the total direct detection rate, especially for light nucleus. With this scenario, one could explain recent DAMA and CoGeNT results.

  15. The AMIDAS Website: An Online Tool for Direct Dark Matter Detection Experiments

    NASA Astrophysics Data System (ADS)

    Shan, Chung-Lin

    2010-02-01

    Following our long-erm work on development of model-independent data analysis methods for reconstructing the one-dimensional velocity distribution function of halo WIMPs as well as for determining their mass and couplings on nucleons by using data from direct Dark Matter detection experiments directly, we combined the simulation programs to a compact system: AMIDAS (A Model-Independent Data Analysis System). For users' convenience an online system has also been established at the same time. AMIDAS has the ability to do full Monte Carlo simulations, faster theoretical estimations, as well as to analyze (real) data sets recorded in direct detection experiments without modifying the source code. In this article, I give an overview of functions of the AMIDAS code based on the use of its website.

  16. 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.

  17. Electrical percolation-based biosensor for real-time direct detection of staphylococcal enterotoxin B (SEB).

    PubMed

    Yang, Minghui; Sun, Steven; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

    2010-08-15

    Electrical percolation-based biosensing is a new technology. This is the first report of an electrical percolation-based biosensor for real-time detection. The label-free biosensor is based on electrical percolation through a single-walled carbon nanotubes (SWNTs)-antibody complex that forms a network functioning as a "Biological Semiconductor" (BSC). The conductivity of a BSC is directly related to the number of contacts facilitated by the antibody-antigen "connectors" within the SWNT network. BSCs are fabricated by immobilizing a pre-functionalized SWNTs-antibody complex directly on a poly(methyl methacrylate) (PMMA) and polycarbonate (PC) surface. Each BSC is connected via silver electrodes to a computerized ohmmeter, thereby enabling a continuous electronic measurement of molecular interactions (e.g. antibody-antigen binding) via the change in resistance. Using anti-staphylococcal enterotoxin B (SEB) IgG to functionalize the BSC, we demonstrate that the biosensor was able to detect SEB at concentrations as low as 5 ng/mL at a signal to baseline (S/B) ratio of 2. Such measurements were performed on the chip in wet conditions. The actuation of the chip by SEB is immediate, permitting real-time signal measurements. In addition to this "direct" label-free detection mode, a secondary antibody can be used to "label" the target molecule bound to the BSC in a manner analogous to an immunological sandwich "indirect" detection-type assay. Although a secondary antibody is not needed for direct detection, the indirect mode of detection may be useful as an additional measurement to verify or amplify signals from direct detection in clinical, food safety and other critical assays. The BSC was used to measure SEB both in buffer and in milk, a complex matrix, demonstrating the potential of electrical percolation-based biosensors for real-time label-free multi-analyte detection in clinical and complex samples. Assembly of BSCs is simple enough that multiple sensors can be

  18. Using a large area CMOS APS for direct chemiluminescence detection in Western blotting electrophoresis

    NASA Astrophysics Data System (ADS)

    Esposito, Michela; Newcombe, Jane; Anaxagoras, Thalis; Allinson, Nigel M.; Wells, Kevin

    2012-03-01

    Western blotting electrophoretic sequencing is an analytical technique widely used in Functional Proteomics to detect, recognize and quantify specific labelled proteins in biological samples. A commonly used label for western blotting is Enhanced ChemiLuminescence (ECL) reagents based on fluorescent light emission of Luminol at 425nm. Film emulsion is the conventional detection medium, but is characterized by non-linear response and limited dynamic range. Several western blotting digital imaging systems have being developed, mainly based on the use of cooled Charge Coupled Devices (CCDs) and single avalanche diodes that address these issues. Even so these systems present key drawbacks, such as a low frame rate and require operation at low temperature. Direct optical detection using Complementary Metal Oxide Semiconductor (CMOS) Active Pixel Sensors (APS)could represent a suitable digital alternative for this application. In this paper the authors demonstrate the viability of direct chemiluminescent light detection in western blotting electrophoresis using a CMOS APS at room temperature. Furthermore, in recent years, improvements in fabrication techniques have made available reliable processes for very large imagers, which can be now scaled up to wafer size, allowing direct contact imaging of full size western blotting samples. We propose using a novel wafer scale APS (12.8 cm×13.2 cm), with an array architecture using two different pixel geometries that can deliver an inherently low noise and high dynamic range image at the same time representing a dramatic improvement with respect to the current western blotting imaging systems.

  19. Direct Write Protein Patterns for Multiplexed Cytokine Detection from Live Cells Using Electron Beam Lithography.

    PubMed

    Lau, Uland Y; Saxer, Sina S; Lee, Juneyoung; Bat, Erhan; Maynard, Heather D

    2016-01-26

    Simultaneous detection of multiple biomarkers, such as extracellular signaling molecules, is a critical aspect in disease profiling and diagnostics. Precise positioning of antibodies on surfaces, especially at the micro- and nanoscale, is important for the improvement of assays, biosensors, and diagnostics on the molecular level, and therefore, the pursuit of device miniaturization for parallel, fast, low-volume assays is a continuing challenge. Here, we describe a multiplexed cytokine immunoassay utilizing electron beam lithography and a trehalose glycopolymer as a resist for the direct writing of antibodies on silicon substrates, allowing for micro- and nanoscale precision of protein immobilization. Specifically, anti-interleukin 6 (IL-6) and antitumor necrosis factor alpha (TNFα) antibodies were directly patterned. Retention of the specific binding properties of the patterned antibodies was shown by the capture of secreted cytokines from stimulated RAW 264.7 macrophages. A sandwich immunoassay was employed using gold nanoparticles and enhancement with silver for the detection and visualization of bound cytokines to the patterns by localized surface plasmon resonance detected with dark-field microscopy. Multiplexing with both IL-6 and TNFα on a single chip was also successfully demonstrated with high specificity and in relevant cell culture conditions and at different times after cell stimulation. The direct fabrication of capture antibody patterns for cytokine detection described here could be useful for biosensing applications.

  20. Effect of Detector Dead Time on the Performance of Optical Direct-Detection Communication Links

    NASA Technical Reports Server (NTRS)

    Chen, C.-C.

    1988-01-01

    Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detect ion sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulted (PPM) channel is studied by analyzing the error probability. It is shown that, when back- ground noise is negligible, the performance of the detector with dead time is similar to that o f a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on background intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

  1. Effect of detector dead time on the performance of optical direct-detection communication links

    NASA Astrophysics Data System (ADS)

    Chen, C.-C.

    1988-05-01

    Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detection sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulated (PPM) channel is studied by analyzing the error probability. It is shown that, when background noise is negligible, the performance of the detector with dead time is similar to that of a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on badkground intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

  2. Detection of the hydroperoxyl radical HO2 toward ρ Ophiuchi A. Additional constraints on the water chemical network

    NASA Astrophysics Data System (ADS)

    Parise, B.; Bergman, P.; Du, F.

    2012-05-01

    Context. Hydrogen peroxide (HOOH) was recently detected toward ρ Oph A. Subsequent astrochemical modeling that included reactions in the gas phase and on the surface of dust grains was able to explain the observed abundance, and highlighted the importance of grain chemistry in the formation of HOOH as an intermediate product in water formation. This study also predicted that the hydroperoxyl radical HO2, the precursor of HOOH, should be detectable. Aims: We aim at detecting the hydroperoxyl radical HO2 in ρ Oph A. Methods: We used the IRAM 30 m and the APEX telescopes to target the brightest HO2 lines at about 130 and 260 GHz. Results: We detect five lines of HO2 (comprising seven individual molecular transitions). The fractional abundance of HO2 is found to be about 10-10, a value similar to the abundance of HOOH. This observational result is consistent with the prediction of the above mentioned astrochemical model, and thereby validates our current understanding of the water formation on dust grains. Conclusions: This detection, anticipated by a sophisticated gas-grain chemical model, demonstrates that models of grain chemistry have improved tremendously and that grain surface reactions now form a crucial part of the overall astrochemical network. Based on observations carried out with the IRAM 30 m and the APEX telescopes. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). APEX is a collaboration between the Max Planck Institute for Radio Astronomy, the Onsala Space Observatory, and the European Southern Observatory.

  3. Deducing the nature of dark matter from direct and indirect detection experiments in the absence of collider signatures of new physics

    SciTech Connect

    Beltran, Maria; Hooper, Dan; Kolb, Edward W.; Krusberg, Zosia A. C.

    2009-08-15

    Despite compelling arguments that significant discoveries of physics beyond the standard model are likely to be made at the Large Hadron Collider, it remains possible that this machine will make no such discoveries, or will make no discoveries directly relevant to the dark matter problem. In this article, we study the ability of astrophysical experiments to deduce the nature of dark matter in such a scenario. In most dark matter studies, the relic abundance and detection prospects are evaluated within the context of some specific particle physics model or models (e.g., supersymmetry). Here, assuming a single weakly interacting massive particle constitutes the Universe's dark matter, we attempt to develop a model-independent approach toward the phenomenology of such particles in the absence of any discoveries at the Large Hadron Collider. In particular, we consider generic fermionic or scalar dark matter particles with a variety of interaction forms, and calculate the corresponding constraints from and sensitivity of direct and indirect detection experiments. The results may provide some guidance in disentangling information from future direct and indirect detection experiments.

  4. Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics

    PubMed Central

    Hou, Han Wei; Bhattacharyya, Roby P.; Hung, Deborah T.; Han, Jongyoon

    2015-01-01

    Detection of bacteria in bloodstream infections and their antibiotic susceptibility patterns is critical to guide therapeutic decision-making for optimal patient care. Current culture-based assays are too slow (>48 hrs), leading to excessive up-front use of broad-spectrum antibiotics and/or incorrect antibiotic choices due to resistant bacteria, each with deleterious consequences for patient care and public health. To approach this problem, we describe a method to rapidly isolate bacteria from whole blood using inertial microfluidics and directly determine pathogen identity and antibiotic susceptibility with hybridization-based RNA detection. Using the principle of Dean flow fractionation, bacteria are separated from host blood cells in a label-free separation method with efficient recovery of even low abundance bacteria. Ribosomal RNA detection can then be applied for direct identification of low abundance pathogens (~100/mL) from blood without culturing or enzymatic amplification. Messenger RNA detection of antibiotic-responsive transcripts after brief drug exposure permits rapid susceptibility determination from bacteria with minimal culturing (~105/mL). This unique coupling of microfluidic cell separation with RNA-based molecular detection techniques represents significant progress towards faster diagnostics (~8 hours) to guide antibiotic therapy. PMID:25882432

  5. Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics.

    PubMed

    Hou, Han Wei; Bhattacharyya, Roby P; Hung, Deborah T; Han, Jongyoon

    2015-05-21

    Detection of bacteria in bloodstream infections and their antibiotic susceptibility patterns is critical to guide therapeutic decision-making for optimal patient care. Current culture-based assays are too slow (>48 h), leading to excessive up-front use of broad-spectrum antibiotics and/or incorrect antibiotic choices due to resistant bacteria, each with deleterious consequences for patient care and public health. To approach this problem, we describe a method to rapidly isolate bacteria from whole blood using inertial microfluidics and directly determine pathogen identity and antibiotic susceptibility with hybridization-based RNA detection. Using the principle of Dean flow fractionation, bacteria are separated from host blood cells in a label-free separation method with efficient recovery of even low abundance bacteria. Ribosomal RNA detection can then be applied for direct identification of low abundance pathogens (~100 per mL) from blood without culturing or enzymatic amplification. Messenger RNA detection of antibiotic-responsive transcripts after brief drug exposure permits rapid susceptibility determination from bacteria with minimal culturing (~10(5) per mL). This unique coupling of microfluidic cell separation with RNA-based molecular detection techniques represents significant progress towards faster diagnostics (~8 hours) to guide antibiotic therapy.

  6. Rapid, Portable, Multiplexed Detection of Bacterial Pathogens Directly from Clinical Sample Matrices.

    PubMed

    Phaneuf, Christopher R; Mangadu, Betty; Piccini, Matthew E; Singh, Anup K; Koh, Chung-Yan

    2016-01-01

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. This platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min. PMID:27669320

  7. Rapid, Portable, Multiplexed Detection of Bacterial Pathogens Directly from Clinical Sample Matrices.

    PubMed

    Phaneuf, Christopher R; Mangadu, Betty; Piccini, Matthew E; Singh, Anup K; Koh, Chung-Yan

    2016-09-23

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. This platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min.

  8. Monitoring the impact of litter in large vertebrates in the Mediterranean Sea within the European Marine Strategy Framework Directive (MSFD): constraints, specificities and recommendations.

    PubMed

    Galgani, F; Claro, F; Depledge, M; Fossi, C

    2014-09-01

    In its decision (2010/477/EU) relating to the European Marine Strategy Framework Directive (MSFD, 2008/56/EC), the European Commission identified the following points as focuses for monitoring: (i) 10.1.1: Trends in the amount, source and composition of litter washed ashore and/or deposited on coastlines, (ii) 10.1.2: Trends in the amount and composition of litter in the water column and accumulation on the sea floor, (iii) 10.1.3: Trends in the amount, distribution and composition of micro-particles (mainly microplastics), and (iv) 10.2.1: Trends in the amount and composition of litter ingested by marine animals. Monitoring the impacts of litter will be considered further in 2014. At that time, the strategy will be discussed in the context of the Mediterranean Sea, providing information on constraints, protocols, existing harm and research needed to support monitoring efforts. The definition of targets and acceptable levels of harm must take all factors into account, whether entanglement, ingestion, the transport and release of pollutants, the transport of alien species and socio-economic impacts. It must also reflect on the practical deployment of "ingestion" measures (10.2.1). The analysis of existing data will reveal the potential and suitability of some higher trophic level organisms (fish, turtles, birds and mammals) for monitoring the adverse effects of litter. Sea turtles appear to be useful indicator species, but the definition of an ecological quality objective is still needed, as well as research on alternative potential indicator species. PMID:24612883

  9. Detection of Directions of Gravity by Organisms and Contributions to SmaggIce

    NASA Technical Reports Server (NTRS)

    Dill, Loren H.

    2003-01-01

    Research covers the following: In the Microgravity Environment and Telescience Branch, a study wasI extended thar focused upon a flagellated alga or other swimming microbe and the effect of gravity upon its swimming direction. It has long been known that many organisms tend to swim up or down on Earth. How organisms detect the direction of gravity is a question not fully resolved. The response of such organisms to reduced gravity or the absence of gravity is also of interest, particularly because the expected modified behavior may affect the health of astronauts.

  10. Method and apparatus for detecting the direction and distance to a target well casing

    SciTech Connect

    Kuckes, A.F.

    1984-04-17

    A method and an apparatus for determining the exact direction of and distance to a nearby target well having a steel casing from a borehole are disclosed. A long solenoid having a coil wound on a high permeability core for generating a source magnetic field which, in the absence of a target well, has axial symmetry and is characterized by having a magnetic pole at each end of the core is provided. Directly adjacent to one end of the core is a 3-component ring-type fluxgate magnetometer to detect magnetic field components perpendicular to the axis of the solenoid. The detection apparatus is located in a borehole, and the magnetic field generated.

  11. Modeling the performance of direct-detection Doppler lidar systems including cloud and solar background variability.

    PubMed

    McGill, M J; Hart, W D; McKay, J A; Spinhirne, J D

    1999-10-20

    Previous modeling of the performance of spaceborne direct-detection Doppler lidar systems assumed extremely idealized atmospheric models. Here we develop a technique for modeling the performance of these systems in a more realistic atmosphere, based on actual airborne lidar observations. The resulting atmospheric model contains cloud and aerosol variability that is absent in other simulations of spaceborne Doppler lidar instruments. To produce a realistic simulation of daytime performance, we include solar radiance values that are based on actual measurements and are allowed to vary as the viewing scene changes. Simulations are performed for two types of direct-detection Doppler lidar system: the double-edge and the multichannel techniques. Both systems were optimized to measure winds from Rayleigh backscatter at 355 nm. Simulations show that the measurement uncertainty during daytime is degraded by only approximately 10-20% compared with nighttime performance, provided that a proper solar filter is included in the instrument design. PMID:18324169

  12. Modeling the Performance of Direct-Detection Doppler Lidar Systems in Real Atmospheres

    NASA Technical Reports Server (NTRS)

    McGill, Matthew J.; Hart, William D.; McKay, Jack A.; Spinhirne, James D.

    1999-01-01

    Previous modeling of the performance of spaceborne direct-detection Doppler lidar systems has assumed extremely idealized atmospheric models. Here we develop a technique for modeling the performance of these systems in a more realistic atmosphere, based on actual airborne lidar observations. The resulting atmospheric model contains cloud and aerosol variability that is absent in other simulations of spaceborne Doppler lidar instruments. To produce a realistic simulation of daytime performance, we include solar radiance values that are based on actual measurements and are allowed to vary as the viewing scene changes. Simulations are performed for two types of direct-detection Doppler lidar systems: the double-edge and the multi-channel techniques. Both systems were optimized to measure winds from Rayleigh backscatter at 355 nm. Simulations show that the measurement uncertainty during daytime is degraded by only about 10-20% compared to nighttime performance, provided a proper solar filter is included in the instrument design.

  13. Pinning down inelastic dark matter in the Sun and in direct detection

    NASA Astrophysics Data System (ADS)

    Blennow, Mattias; Clementz, Stefan; Herrero-Garcia, Juan

    2016-04-01

    We study the solar capture rate of inelastic dark matter with endothermic and/or exothermic interactions. By assuming that an inelastic dark matter signal will be observed in next generation direct detection experiments we can set a lower bound on the capture rate that is independent of the local dark matter density, the velocity distribution, the galactic escape velocity as well as the scattering cross section. In combination with upper limits from neutrino observatories we can place upper bounds on the annihilation channels leading to neutrinos. We find that, while endothermic scattering limits are weak in the isospin-conserving case, strong bounds may be set for exothermic interactions, in particular in the spin-dependent case. Furthermore, we study the implications of observing two direct detection signals, in which case one can halo-independently obtain the dark matter mass and the mass splitting, and disentangle the endothermic/exothermic nature of the scattering. Finally we discuss isospin violation.

  14. 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.

  15. Direct Fluorescent Detection of a Polymethoxyflavone in Cell Culture and Mouse Tissue.

    PubMed

    Chen, Jingjing; Song, Mingyue; Wu, Xian; Zheng, Jinkai; He, Lili; McClements, David Julian; Decker, Eric; Xiao, Hang

    2015-12-16

    Convenient detection methods for bioactive food compounds and their metabolites in biological samples are needed to better understand their mechanism of actions. Herein, we developed a novel approach to directly monitor and visualize the distribution of 5,3',4'-tridemethylnobiletin (TDN), a unique polymethoxyflavone metabolite derived from citrus polymethoxyflavone, in biological samples such as cultured cells and mouse colonic tissues. Our results showed that a fluorescent conjugate could be formed between TDN and 2-aminoethyl diphenyl borate (DPBA) under simple reaction conditions, which was confirmed by both Raman spectroscopy and mass spectroscopy. We further demonstrated the application of DPBA-based conjugation reaction in the characterization of TDN in different biological samples including floating cells, adherent cells, and animal tissues. This is the first report demonstrating direct fluorescent detection of polymethoxyflavone in biological samples. PMID:26618604

  16. Colorless ONU implementation for WDM-PON using direct-detection optical OFDM

    NASA Astrophysics Data System (ADS)

    Feng, Min; Luo, Qing-long; Bai, Cheng-lin

    2013-03-01

    A novel architecture for the colorless optical network unit (ONU) is proposed and experimentally demonstrated with direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM). In this architecture, polarization-division multiplexing is used to reduce the cost at ONU. In optical line terminal (OLT), quadrature amplitude modulation (QAM) intensity-modulated OFDM signal with x-polarization at 10 Gbit/s is transmitted as downstream. At each ONU, the optical OFDM signal is demodulated with direct detection, and γ-polarization signal is modulated for upstream on-off keying (OOK) data at 5 Gbit/s. Simulation results show that the power penalty is negligible for both optical OFDM downstream and the on-off keying upstream signals after over 50 km single-mode fiber (SMF) transmission.

  17. Advantages of horizontal directional Theta method to detect the edges of full tensor gravity gradient data

    NASA Astrophysics Data System (ADS)

    Yuan, Yuan; Gao, Jin-Yao; Chen, Ling-Na

    2016-07-01

    Full tensor gravity gradient data contain nine signal components. They include higher frequency signals than traditional gravity data, which can extract the small-scale features of the sources. Edge detection has played an important role in the interpretation of potential-field data. There are many methods that have been proposed to detect and enhance the edges of geological bodies based on horizontal and vertical derivatives of potential-field data. In order to make full use of all the measured gradient components, we need to develop a new edge detector to process the full tensor gravity gradient data. We first define the directional Theta and use the horizontal directional Theta to define a new edge detector. This method was tested on synthetic and real full tensor gravity gradient data to validate its feasibility. Compared the results with other balanced detectors, the new detector can effectively delineate the edges and does not produce any additional false edges.

  18. Reduced electrical bandwidth receivers for direct detection 4-ary PPM optical communication intersatellite links

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic M.; Sun, Xiaoli

    1993-01-01

    One of the major sources of noise in a direct detection optical communication receiver is the shot noise due to the quantum nature of the photodetector. The shot noise is signal dependent and is neither Gaussian nor wide sense stationary. When a photomultiplier tube (PMT) or an avalanche photodiode (APD) is used, there is also a multiplicative excess noise due to the randomness of the internal photodetector gain. Generally speaking, the radio frequency (RF) communication theory cannot be applied to direct detection optical communication systems because noise in RF communication systems is usually additive and Gaussian. A receiver structure which is mathematically optimal for signal dependent shot noise is derived. Several suboptimal receiver structures are discussed and compared with the optimal receiver. The objective is to find a receiver structure which is easy to implement and gives close to optimal performance.

  19. Directed Design of Experiments for Validating Probability of Detection Capability of NDE Systems (DOEPOD)

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.

    2008-01-01

    The capability of an inspection system is established by applications of various methodologies to determine the probability of detection (POD). One accepted metric of an adequate inspection system is that there is 95% confidence that the POD is greater than 90% (90/95 POD). Directed design of experiments for probability of detection (DOEPOD) has been developed to provide an efficient and accurate methodology that yields observed POD and confidence bounds for both Hit- Miss or signal amplitude testing. Specifically, DOEPOD demands utilization of observance of occurrences. Directed DOEPOD does not assume prescribed POD logarithmic or similar functions with assumed adequacy over a wide range of flaw sizes and inspection system technologies, so that multi-parameter curve fitting or model optimization approaches to generate a POD curve are not required.

  20. Neutron beam test of barium fluoride crystal for dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Guo, C.; Ma, X. H.; Wang, Z. M.; Bao, J.; Dai, C. J.; Guan, M. Y.; Liu, J. C.; Li, Z. H.; Ren, J.; Ruan, X. C.; Yang, C. G.; Yu, Z. Y.; Zhong, W. L.

    2016-10-01

    In order to test the capabilities of Barium Fluoride (BaF2) crystal for dark matter direct detection, nuclear recoils are studied with mono-energetic neutron beam. The energy spectra of nuclear recoils, quenching factors for elastic scattering neutrons and discrimination capability between neutron inelastic scattering events and γ events are obtained for various recoil energies of the F content in BaF2.

  1. Direct 13C-detection for carbonyl relaxation studies of protein dynamics.

    PubMed

    Pasat, Gabriela; Zintsmaster, John S; Peng, Jeffrey W

    2008-08-01

    We describe a method that uses direct 13C-detection for measuring rotating-frame carbonyl (13CO) relaxation rates to describe protein functional dynamics. Key advantages of method include the following: (i) unique access to 13CO groups that lack a scalar-coupled 15N-1H group; (ii) insensitivity to 15N/1H exchange-broadening that can derail 1H-detected 15N and HNCO methods; (iii) avoidance of artifacts caused by incomplete water suppression. We demonstrate the approach for both backbone and side-chain 13CO groups. Accuracy of the 13C-detected results is supported by their agreement with those obtained from established HNCO-based approaches. Critically, we show that the 13C-detection approach provides access to the 13CO groups of functionally important residues that are invisible via 1H-detected HNCO methods because of exchange-broadening. Hence, the 13C-based method fills gaps inherent in canonical 1H-detected relaxation experiments, and thus provides a novel complementary tool for NMR studies of biomolecular flexibility. PMID:18514001

  2. You can hide but you have to run: direct detection with vector mediators

    NASA Astrophysics Data System (ADS)

    D'Eramo, Francesco; Kavanagh, Bradley J.; Panci, Paolo

    2016-08-01

    We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running. In some cases the inclusion of these effects changes the bounds by several orders of magnitude, as a consequence of operator mixing which generates new interactions at low energy. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Finally, we provide tools to facilitate the inclusion of these effects in future studies: general approximate expressions for the low energy couplings and a public code runDM to evolve the couplings between arbitrary energy scales.

  3. How to detect the Granger-causal flow direction in the presence of additive noise?

    PubMed

    Vinck, Martin; Huurdeman, Lisanne; Bosman, Conrado A; Fries, Pascal; Battaglia, Francesco P; Pennartz, Cyriel M A; Tiesinga, Paul H

    2015-03-01

    Granger-causality metrics have become increasingly popular tools to identify directed interactions between brain areas. However, it is known that additive noise can strongly affect Granger-causality metrics, which can lead to spurious conclusions about neuronal interactions. To solve this problem, previous studies have proposed the detection of Granger-causal directionality, i.e. the dominant Granger-causal flow, using either the slope of the coherency (Phase Slope Index; PSI), or by comparing Granger-causality values between original and time-reversed signals (reversed Granger testing). We show that for ensembles of vector autoregressive (VAR) models encompassing bidirectionally coupled sources, these alternative methods do not correctly measure Granger-causal directionality for a substantial fraction of VAR models, even in the absence of noise. We then demonstrate that uncorrelated noise has fundamentally different effects on directed connectivity metrics than linearly mixed noise, where the latter may result as a consequence of electric volume conduction. Uncorrelated noise only weakly affects the detection of Granger-causal directionality, whereas linearly mixed noise causes a large fraction of false positives for standard Granger-causality metrics and PSI, but not for reversed Granger testing. We further show that we can reliably identify cases where linearly mixed noise causes a large fraction of false positives by examining the magnitude of the instantaneous influence coefficient in a structural VAR model. By rejecting cases with strong instantaneous influence, we obtain an improved detection of Granger-causal flow between neuronal sources in the presence of additive noise. These techniques are applicable to real data, which we demonstrate using actual area V1 and area V4 LFP data, recorded from the awake monkey performing a visual attention task.

  4. Comparison of the direct platelet immunofluorescence test (direct PIFT) with a modified direct monoclonal antibody-specific immobilization of platelet antigens (direct MAIPA) in detection of platelet-associated IgG.

    PubMed

    Joutsi, L; Kekomäki, R

    1997-01-01

    Glycoprotein (GP)-specific platelet-associated IgG (PA-IgG) may be demonstrable in autoimmune-mediated thrombocytopenia. We studied 159 consecutive patients with histories of thrombocytopenia by a modified direct monoclonal antibody-specific immobilization of platelet antigens (direct MAIPA) assay, which immobilizes GP IIb/ IIIa, GP Ib/IX and GP Ia/IIa simultaneously. This modification requires smaller quantities of platelets than standard measurements performed separately. PA-IgG was present in 84/159 (53%) patients, as shown by the direct platelet immunofluorescence test (PIFT) with flow cytometry as a reference. PA-IgG against GP IIb/IIIa and/or GP Ib/IX and/or GP Ia/IIa was noted in 46 patients (29%), of whom 93% (43/46)-were also PA-IgG positive. The amount of PA-IgG detected by PIFT correlated directly with that detected by direct MAIPA (r = 0.71; P < 0.001). Only three patients 12548 with negative direct PIFT had GP-specific PA-IgG. GPV-specific PA-IgG was detected in 13 (10%) of the 125 patients, in whom further studies could be performed. In the subgroup of patients with GP-specific PA-IgG, the median fluorescence intensities of direct PIFT were higher than in patients with no GP-specific PA-IgG (P < 0.001). Direct PIFT and direct MAIPA divided the patients into asymmetric subgroups. However, the relative roles of these tests in the diagnosis of autoimmune-mediated thrombocytopenia await further studies. PMID:9012711

  5. Direct molecule-specific glucose detection by Raman spectroscopy based on photonic crystal fiber.

    PubMed

    Yang, Xuan; Zhang, Alissa Y; Wheeler, Damon A; Bond, Tiziana C; Gu, Claire; Li, Yat

    2012-01-01

    This paper reports the first step toward the development of a glucose biosensor based on Raman spectroscopy and a photonic crystal fiber (PCF) probe. Historically, it has been very challenging to detect glucose directly by Raman spectroscopy due to its inherently small Raman scattering cross-section. In this work, we report the first quantitative glucose Raman detection in the physiological concentration range (0-25 mM) with a low laser power (2 mW), a short integration time (30 s), and an extremely small sampling volume (~50 nL) using the highly sensitive liquid-filled PCF probe. As a proof of concept, we also demonstrate the molecular specificity of this technique in the presence of a competing sugar, such as fructose. High sensitivity, flexibility, reproducibility, low cost, small sampling volume, and in situ remote sensing capability make PCF a very powerful platform for potential glucose detection based on Raman spectroscopy. PMID:22120042

  6. Direct detection of Theileria annulata in bovine blood samples using standard and isothermal DNA amplification approaches.

    PubMed

    Gomes, Jacinto; Inácio, João

    2015-01-01

    Tropical theileriosis is a tick-borne disease responsible for important health problems in cattle, caused by the hemoprotozoan Theileria annulata. Traditionally, detection of Theileria pathogens in infected animals requires the microscopic examination of stained-blood smears and serological methods. Molecular diagnostic assays have been developed for the detection of Theileria parasites, including PCR-based and reverse line blotting approaches, but these methods usually demand qualified personnel, complex instrumentation, and expensive materials. Loop-mediated isothermal amplification (LAMP) can facilitate the design of molecular assays independent of the use of sophisticated equipment. In this chapter we describe the application of two molecular assays for the direct detection of T. annulata in bovine blood samples, based in real-time PCR and LAMP, both targeting the Tams1-encoding gene of this parasite.

  7. Development of a rapid diagnostic test for pertussis: direct detection of pertussis toxin in respiratory secretions.

    PubMed Central

    Friedman, R L; Paulaitis, S; McMillan, J W

    1989-01-01

    Monoclonal antibodies (MAb) were produced against the specific Bordetella pertussis antigen pertussis toxin (PT). In preliminary studies, one MAb (IB12) was selected and used in an enzyme-linked dot blot immunoassay to evaluate the ability of the method to detect known amounts of PT in control experiments and to test its potential for direct detection of PT in nasopharyngeal secretion (NP) specimens from patients with confirmed cases of whooping cough. The dot blot assay was able to detect PT at levels as low as 10 ng per dot in either buffer or control NP specimens. The assay demonstrated specificity, reacting only with dot blots of whole B. pertussis and not Bordetella bronchiseptica, Bordetella parapertussis, or other bacterial strains. In preliminary studies, NP aspirate, swab, and wash specimens were compared. The specimen of choice was found to be the NP aspirate, for which 100% positive results were found in the assay. These initial studies suggest that the dot blot immunoassay in which a MAb is used for direct detection of PT in NP specimens may be useful as a rapid diagnostic test for pertussis. Images PMID:2808670

  8. Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

    PubMed

    Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

    2012-01-01

    Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. PMID:21728204

  9. Direction sensitive fall detection using a triaxial accelerometer and a barometric pressure sensor.

    PubMed

    Tolkiehn, Marie; Atallah, Louis; Lo, Benny; Yang, Guang-Zhong

    2011-01-01

    Falling is one of the leading causes of serious health decline or injury-related deaths in the elderly. For survivors of a fall, the resulting health expenses can be a devastating burden, largely because of the long recovery time and potential comorbidities that ensue. The detection of a fall is, therefore, important in care of the elderly for decreasing the reaction time by the care-givers especially for those in care who are particularly frail or living alone. Recent advances in motion-sensor technology have enabled wearable sensors to be used efficiently for pervasive care of the elderly. In addition to fall detection, it is also important to determine the direction of a fall, which could help in the location of joint weakness or post-fall fracture. This work uses a waist-worn sensor, encompassing a 3D accelerometer and a barometric pressure sensor, for reliable fall detection and the determination of the direction of a fall. Also assessed is an efficient analysis framework suitable for on-node implementation using a low-power micro-controller that involves both feature extraction and fall detection. A detailed laboratory analysis is presented validating the practical application of the system.

  10. Investigation of photochemical reaction products of glucose formed during direct UV detection in CE.

    PubMed

    Schmid, Thomas; Himmelsbach, Markus; Buchberger, Wolfgang W

    2016-04-01

    In CE, saccharides are accessible to direct UV detection due to a photochemical reaction in the detection window of the separation capillary resulting in the formation of UV absorbing substances. Employing a CE method that allows long in-capillary irradiation with subsequent UV and MS detection, the present study could identify several reaction products of glucose. Among these were UV absorbing substances so far unknown to be formed during direct UV detection with the chemical formulas C4 H6 O2 , C5 H6 O4 , C5 H8 O3, and C6 H8 O5 . Investigations of the impact of the irradiation time revealed differences between these reaction products suggesting differing reaction mechanisms especially for the smallest products. More detailed information could be obtained by experiments with isotope-labeled substrates performed to determine the parts of glucose that are converted to the particular reaction products. In addition, structural formulas for the reaction products were suggested based on HPLC-MS/MS measurements of off-line irradiated glucose solutions which revealed the existence of functional groups such as carboxylic acid or aldehyde groups.

  11. Detection of short tandem repeat polymorphisms from human nails using direct polymerase chain reaction method.

    PubMed

    Tie, Jian; Uchigasaki, Seisaku

    2014-11-01

    Human nail is an important forensic material for parental testing and individual identification in large-scale disasters. Detection of STR polymorphism from hard tissues generally requires DNA purification, which is technically complicated and time consuming. In the present study, we attempted to detect STR polymorphisms from untreated human nail samples by direct PCR amplification method using the primer mixture supplied with the GenePrint® SilverSTR® III System or the AmpFℓSTR® Identifiler® PCR Amplification Kit, and Tks Gflex DNA polymerase known to be effective for amplification from crude samples. A nail fragment measuring approximately 1.5 mm in breadth and 0.5 mm in length was placed directly into a PCR tube, and various PCR conditions were tested. The PCR products were analyzed by denaturing acrylamide gel electrophoresis or CE. Multiple STR polymorphisms were detected successfully. This method that detects STR polymorphisms not only from fresh human fingernails, but also from old nail fragments stored at room temperature for up to 10 years is expected to become a novel DNA analytical method in forensic medicine and genetic studies.

  12. Readout strategies for directional dark matter detection beyond the neutrino background

    NASA Astrophysics Data System (ADS)

    O'Hare, Ciaran A. J.; Green, Anne M.; Billard, Julien; Figueroa-Feliciano, Enectali; Strigari, Louis E.

    2015-09-01

    The search for weakly interacting massive particles (WIMPs) by direct detection faces an encroaching background due to coherent neutrino-nucleus scattering. As the sensitivity of these experiments improves, the question of how to best distinguish a dark matter signal from neutrinos will become increasingly important. A proposed method of overcoming this so-called "neutrino floor" is to utilize the directional signature that both neutrino- and dark-matter-induced recoils possess. We show that directional experiments can indeed probe WIMP-nucleon cross sections below the neutrino floor with little loss in sensitivity due to the neutrino background. In particular we find at low WIMP masses (around 6 GeV) the discovery limits for directional detectors penetrate below the nondirectional limit by several orders of magnitude. For high WIMP masses (around 100 GeV), the nondirectional limit is overcome by a factor of a few. Furthermore we show that even for directional detectors which can only measure one- or two-dimensional projections of the three-dimensional recoil track, the discovery potential is only reduced by a factor of 3 at most. We also demonstrate that while the experimental limitations of directional detectors, such as sense recognition and finite angular resolution, have a detrimental effect on the discovery limits, it is still possible to overcome the ultimate neutrino background faced by nondirectional detectors.

  13. Direct detection of Mycobacterium tuberculosis complex in bovine and bubaline tissues through nested-PCR.

    PubMed

    Araújo, Cristina P; Osório, Ana Luiza A R; Jorge, Klaudia S G; Ramos, Carlos A N; Souza Filho, Antonio F; Vidal, Carlos E S; Vargas, Agueda P C; Roxo, Eliana; Rocha, Adalgiza S; Suffys, Philip N; Fonseca, Antônio A; Silva, Marcio R; Barbosa Neto, José D; Cerqueira, Valíria D; Araújo, Flábio R

    2014-01-01

    Post-mortem bacterial culture and specific biochemical tests are currently performed to characterize the etiologic agent of bovine tuberculosis. Cultures take up to 90 days to develop. A diagnosis by molecular tests such as PCR can provide fast and reliable results while significantly decreasing the time of confirmation. In the present study, a nested-PCR system, targeting rv2807, with conventional PCR followed by real-time PCR, was developed to detect Mycobacterium tuberculosis complex (MTC) organisms directly from bovine and bubaline tissue homogenates. The sensitivity and specificity of the reactions were assessed with DNA samples extracted from tuberculous and non-tuberculous mycobacteria, as well as other Actinomycetales species and DNA samples extracted directly from bovine and bubaline tissue homogenates. Regarding the analytical sensitivity, DNA of the M. bovis AN5 strain was detected up to 1.5 pg by nested-PCR, whereas DNA of M. tuberculosis H37Rv strain was detected up to 6.1 pg. The nested-PCR system showed 100% analytical specificity for MTC when tested with DNA of reference strains of non-tuberculous mycobacteria and closely-related Actinomycetales. A clinical sensitivity level of 76.7% was detected with tissues samples positive for MTC by means of the culture and conventional PCR. A clinical specificity of 100% was detected with DNA from tissue samples of cattle with negative results in the comparative intradermal tuberculin test. These cattle exhibited no visible lesions and were negative in the culture for MTC. The use of the nested-PCR assay to detect M. tuberculosis complex in tissue homogenates provided a rapid diagnosis of bovine and bubaline tuberculosis.

  14. Detection of the insulating gap and conductive filament growth direction in resistive memories

    NASA Astrophysics Data System (ADS)

    Yalon, E.; Karpov, I.; Karpov, V.; Riess, I.; Kalaev, D.; Ritter, D.

    2015-09-01

    Filament growth is a key aspect in the operation of bipolar resistive random access memory (RRAM) devices, yet there are conflicting reports in the literature on the direction of growth of conductive filaments in valence change RRAM devices. We report here that an insulating gap between the filament and the semiconductor electrode can be detected by the metal-insulator-semiconductor bipolar transistor structure, and thus provide information on the filament growth direction. Using this technique, we show how voltage polarity and electrode chemistry control the filament growth direction during electro-forming. The experimental results and the nature of a gap between the filament and an electrode are discussed in light of possible models of filament formation.

  15. Detection of Bi-Directionality in Strain-Gage Balance Calibration Data

    NASA Technical Reports Server (NTRS)

    Ulbrich, Norbert

    2012-01-01

    An indicator variable was developed for both visualization and detection of bi-directionality in wind tunnel strain-gage balance calibration data. First, the calculation of the indicator variable is explained in detail. Then, a criterion is discussed that may be used to decide which gage outputs of a balance have bi- directional behavior. The result of this analysis could be used, for example, to justify the selection of certain absolute value or other even function terms in the regression model of gage outputs whenever the Iterative Method is chosen for the balance calibration data analysis. Calibration data of NASA s MK40 Task balance is analyzed to illustrate both the calculation of the indicator variable and the application of the proposed criterion. Finally, bi directionality characteristics of typical multi piece, hybrid, single piece, and semispan balances are determined and discussed.

  16. Imaging modes for direct electron detection in TEM with column parallel CCD

    NASA Astrophysics Data System (ADS)

    Moldovan, Grigore; Jeffery, Ben; Nomerotski, Andrei; Kirkland, Angus

    2009-08-01

    Electron imaging detectors have become the main limiting factor in transmission electron microscopy (TEM). A transition is now being made from indirect scintillator-coupled cameras to directly exposed detectors, which propose imaging modes that are novel in TEM. This work uses a dataset recoded with a directly exposed column parallel charge-coupled-device (CCD) to characterize modulation transfer and detective quantum efficiency of integrating, binary and counting imaging modes. Results presented here demonstrate that counting mode produces final images with largest contrast and highest efficiency because it takes into account the large lateral displacement of beam electrons in the detector. Counting imaging mode is recommended in TEM to take advantage from the higher sensitivity of directly exposed detectors.

  17. A telephoto camera system with shooting direction control by gaze detection

    NASA Astrophysics Data System (ADS)

    Teraya, Daiki; Hachisu, Takumi; Yendo, Tomohiro

    2015-05-01

    For safe driving, it is important for driver to check traffic conditions such as traffic lights, or traffic signs as early as soon. If on-vehicle camera takes image of important objects to understand traffic conditions from long distance and shows these to driver, driver can understand traffic conditions earlier. To take image of long distance objects clearly, the focal length of camera must be long. When the focal length is long, on-vehicle camera doesn't have enough field of view to check traffic conditions. Therefore, in order to get necessary images from long distance, camera must have long-focal length and controllability of shooting direction. In previous study, driver indicates shooting direction on displayed image taken by a wide-angle camera, a direction controllable camera takes telescopic image, and displays these to driver. However, driver uses a touch panel to indicate the shooting direction in previous study. It is cause of disturb driving. So, we propose a telephoto camera system for driving support whose shooting direction is controlled by driver's gaze to avoid disturbing drive. This proposed system is composed of a gaze detector and an active telephoto camera whose shooting direction is controlled. We adopt non-wear detecting method to avoid hindrance to drive. The gaze detector measures driver's gaze by image processing. The shooting direction of the active telephoto camera is controlled by galvanometer scanners and the direction can be switched within a few milliseconds. We confirmed that the proposed system takes images of gazing straight ahead of subject by experiments.

  18. Direct detection of green fluorescent protein messenger RNA expressed in Escherichia coli by rolling circle amplification.

    PubMed

    Takahashi, Hirokazu; Matsumoto, Atsuko; Sugiyama, Shigeru; Kobori, Toshiro

    2010-06-15

    Prevailing conventional microbial detection methods depend largely on microbial cultivation in selective media that requires several days. Polymerase chain reaction (PCR)-based methods, including quantitative reverse transcription PCR, are also rapid and useful methods for identification of target microbes, although for practical use they still suffer from disadvantages such as contamination problems and cost. Here we demonstrate that RNA-primed rolling circle amplification (RPRCA) using phi29 DNA polymerase, a precircularized probe, and SYBR Green II achieved real-time detection of specific messenger RNA (mRNA) from living microbes. The precircularized DNA probe was prepared by intramolecular ligation using CircLigase and treated by exonuclease I to eliminate uncircularized oligonucleotide, thereby significantly reducing potential noise by nonspecific amplified DNA by-products that affect successive RPRCA. When in vitro transcribed green fluorescent protein (GFP) mRNA was used as a primer, RPRCA could specifically detect at least 1 fmol of this mRNA in the presence of a precircularized probe that had a sequence complementary to the 3' terminus of mRNA without reverse transcription. This method could also detect expressed GFP mRNA present in 10 ng of total RNA isolated from Escherichia coli without DNase treatment. These data suggest that RPRCA has the potential to be a direct, rapid, and convenient method for detecting microbial mRNA.

  19. Determination of bromate ion in drinking water by capillary zone electrophoresis with direct photometric detection.

    PubMed

    Takayanagi, Toshio; Ishida, Makoto; Mbuna, Julius; Driouich, Rim; Motomizu, Shoji

    2006-09-22

    Bromate ion in drinking water was determined by capillary zone electrophoresis (CZE) with direct photometric detection. Bromate ion in the sample solution was introduced and concentrated into the capillary by electrokinetic injection for 50s at -10 kV. Electrophoretic separation was made at an applied voltage of -25 kV and bromate ion was detected at wavelength 193 nm, at which the baseline was stabilized with less UV-absorbing acidic phosphate buffer. Bromate ion was detected within 5 min in the electropherogram. By increasing the electric conductivity in the migrating solution with 10 mM Na2SO4, a limit of detection (LOD) of 9 x 10(-10)M (0.1 microg/L BrO3-) was achieved. The proposed method was applied to the analysis of tap water and river water samples, but bromate ion was not detected. Because the practical samples contain relatively large amount of foreign ionic substances, the tap water sample was diluted to avoid the matrix ions. Bromate ion added in a tap water at the concentration of 8 x 10(-8)M was quantitatively recovered by diluting it 1/10.

  20. Poker Face of Inelastic Dark Matter: Prospects at Upcoming Direct Detection Experiments

    SciTech Connect

    Alves, Daniele S.M.; Lisanti, Mariangela; Wacker, Jay G.; /SLAC

    2011-08-12

    The XENON100 and CRESST experiments will directly test the inelastic dark matter explanation for DAMA's 8.9{sigma} anomaly. This article discusses how predictions for direct detection experiments depend on uncertainties in quenching factor measurements, the dark matter interaction with the Standard Model and the halo velocity distribution. When these uncertainties are accounted for, an order of magnitude variation is found in the number of expected events at CRESST and XENON100. The process of testing the DAMA anomaly highlights many of the challenges inherent to direct detection experiments. In addition to determining the properties of the unknown dark matter particle, direct detection experiments must also consider the unknown flux of the incident dark matter, as well as uncertainties in converting a signal from one target nucleus to another. The predictions for both the CRESST 2009 run and XENON100 2010 run show an order of magnitude uncertainty. The nuclear form factor for {sup 184}W, when combined with additional theoretical and experimental uncertainties, will likely prevent CRESST from refuting the iDM hypothesis with an exposure of {Omicron}(100 kg-d) in a model-independent manner. XENON100, on the other hand, will be able to make a definitive statement about a spin-independent, inelastically scattering dark matter candidate. Still, the CRESST 2009 data can potentially confirm iDM for a large range of parameter space. In case of a positive signal, the combined data from CRESST and XENON100 will start probing the properties of the Milky Way DM profile and the interaction of the SM with the dark matter.

  1. Improving the efficiency of lepidopteran pest detection and surveillance: constraints and opportunities for multiple-species trapping.

    PubMed

    Brockerhoff, Eckehard G; Suckling, D Maxwell; Roques, Alain; Jactel, Hervé; Branco, Manuela; Twidle, Andrew M; Mastro, Victor C; Kimberley, Mark O

    2013-01-01

    Surveillance using attractants for invasive species can allow early detection of new incursions and provide decision support to response programs. Simultaneous trapping for multiple species, by baiting traps with several lures, is expected to increase the number of species that can be targeted in surveillance programs and improve the cost-effectiveness without affecting surveillance coverage. We tested this hypothesis by choosing four potential forest and urban lepidopteran pest species that are present in Europe but not yet in New Zealand and many other countries. We deployed traps in central and southern Europe with single lures or all possible species combinations (up to four lures per trap). There was only limited interference, apparently due to trap saturation, but no evidence for interspecific repellency among lures for gypsy moth, Lymantria dispar, fall webworm, Hyphantria cunea, pine processionary moth, Thaumetopoea pityocampa, and pine shoot moth, Rhyacionia buoliana. To assess what factors may be important in species compatibility/suitability for multiple-species trapping, we combined our results with those of previous studies conducted by the United States Department of Agriculture. For 75 combinations of pheromones, tested singly or in combination, 19 % showed no effect on trap catch for any of the species tested. In the other cases, either one or both species showed a reduction in trap catch. However, few lure combinations caused complete or nearly complete suppression. For most combinations, catches were still sufficiently high for detection purposes. Species from the same superfamily exhibited more interference than more distantly related species. Together, these results suggest that there are opportunities to improve the range of exotic pests under surveillance, at little additional cost, by multiple-species trapping for which compatibility has been demonstrated. PMID:23254379

  2. Direct biosensor immunoassays for the detection of nonmilk proteins in milk powder.

    PubMed

    Haasnoot, W; Olieman, K; Cazemier, G; Verheijen, R

    2001-11-01

    The low prices of some nonmilk proteins make them attractive as potential adulterants in dairy products. An optical biosensor (BIACORE 3000) was used to develop a direct and combined biosensor immunoassay (BIA) for the simultaneous detection of soy, pea, and soluble wheat proteins in milk powders. Affinity-purified polyclonal antibodies raised against the three protein sources were immobilized in different flow channels (Fcs) on the biosensor chip (CM5). Dissolved milk powders were injected (20 microL injections at 20 microL min(-1)) through the serially connected Fcs, and the antibody-bound plant proteins were detected directly. The total run time between samples, including a regeneration step with 5 microL of 10 mM HCl, was 5 min. The limits of detection in milk powder were below 0.1% of plant protein in the total milk protein content. The antibodies also recognized some proteins from other plant sources, which made this BIA even more suitable as a broad screening assay for nonmilk proteins. PMID:11714303

  3. Fabrication of SERS swab for direct detection of trace explosives in fingerprints.

    PubMed

    Gong, Zhengjun; Du, Hongjie; Cheng, Fansheng; Wang, Cong; Wang, Canchen; Fan, Meikun

    2014-12-24

    Swab sampling is of great importance in surface contamination analysis. A cotton swab (cotton Q-tip) was successfully transformed into surface-enhanced Raman scattering (SERS) substrate (SERS Q-tip) through a bottom-up strategy, where Ag NPs were first self-assembled onto the Q-tip followed by in situ growing. The capability for direct swab detection of Raman probe Nile Blue A (NBA) and a primary explosive marker 2,4-dinitrotoluene (2,4-DNT) using the SERS Q-tip was explored. It was found that at optimum conditions, a femotogram of NBA on glass surface could be swab-detected. The lowest detectable amount for 2,4-DNT is only ∼1.2 ng/cm(2) (total amount of 5 ng) on glass surface, 2 orders of magnitude more sensitive than similar surface analysis achieved with infrared technique, and comparable even with that obtained by ion mobility spectrometry-mass spectrometry. Finally, 2,4-DNT left on fingerprints was also analyzed. It was found that SERS signal of 2,4-DNT from 27th fingerprint after touching 2,4-DNT powder can still be clearly identified by swabbing with the SERS Q-tip. We believe this is the first direct SERS swabbing test of explosives on fingerprint on glass. Considering its relative long shelf life (>30 d), the SERS Q-tip may find great potential in future homeland security applications when combined with portable Raman spectrometers.

  4. Direct RNA-based detection of CTX-M β-lactamases in human blood samples.

    PubMed

    Stein, Claudia; Makarewicz, Oliwia; Pfeifer, Yvonne; Brandt, Christian; Pletz, Mathias W

    2015-05-01

    Bloodstream infections with ESBL-producers are associated with increased mortality, which is due to delayed appropriate treatment resulting in clinical failure. Current routine diagnostics for detection of bloodstream infections consists of blood culture followed by species identification and susceptibility testing. In attempts to improve and accelerate diagnostic procedures, PCR-based methods have been developed. These methods focus on species identification covering only a limited number of ESBL coding genes. Therefore, they fail to cover the steadily further evolving genetic diversity of clinically relevant β-lactamases. We have recently designed a fast and novel RNA targeting method to detect and specify CTX-M alleles from bacterial cultures, based on an amplification-pyrosequencing approach. We further developed this assay towards a diagnostic tool for clinical use and evaluated its sensitivity and specificity when applied directly to human blood samples. An optimized protocol for mRNA isolation allows detection of specific CTX-M groups from as little as 100 CFU/mL blood via reverse transcription, amplification, and pyrosequencing directly from human EDTA blood samples as well as from pre-incubated human blood cultures with a turnaround time for test results of <7 h.

  5. Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager

    SciTech Connect

    Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

    2007-04-24

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

  6. Bloch simulations towards direct detection of oscillating magnetic fields using MRI with spin-lock sequence.

    PubMed

    Nagahara, Shizue; Kobayashi, Tetsuo

    2013-01-01

    A new MRI method using the spin-lock sequence has attracted wide attention because of its potential for detecting small oscillating magnetic fields. However, as the mechanism involved is complicated, we visualized the magnetization performance during the spin-lock sequence in order to better understand interaction of the spin-lock pulse and the externally applied oscillating magnetic fields by means of a fast-and-simple method using matrix operations to solve a time-dependent Bloch equation. To improve spin-lock imaging in the detection of small magnetic fields (in an fMRI experiment that modeled neural magnetic fields), we observed that the phenomenon decreases MR signals, which led us to investigate how spin-lock parameters cause the MR signal to decrease; based on this, we determined that MR signals decrease in oscillating magnetic fields that are resonant with the spin-lock pulse. We also determined that MR signals decrease is directly proportional to spin-lock duration. Our results suggest that MRI can feasibly detect oscillating magnetic fields directly by using of the spin-lock sequence.

  7. Tailored magnetic nanoparticles for direct and sensitive detection of biomolecules in biological samples.

    PubMed

    Fornara, Andrea; Johansson, Petter; Petersson, Karolina; Gustafsson, Stefan; Qin, Jian; Olsson, Eva; Ilver, Dag; Krozer, Anatol; Muhammed, Mamoun; Johansson, Christer

    2008-10-01

    We developed nanoparticles with tailored magnetic properties for direct and sensitive detection of biomolecules in biological samples in a single step. Thermally blocked nanoparticles obtained by thermal hydrolysis, functionalized with specific ligands, are mixed with sample solutions, and the variation of the magnetic relaxation due to surface binding is used to detect the presence of biomolecules. The binding significantly increases the hydrodynamic volume of nanoparticles, thus changing their Brownian relaxation frequency which is measured by a specifically developed AC susceptometer. The system was tested for the presence of Brucella antibodies, a dangerous pathogen causing brucellosis with severe effects both on humans and animals, in serum samples from infected cows and the surface of the nanoparticles was functionalized with lipopolysaccharides (LPS) from Brucella abortus. The hydrodynamic volume of LPS-functionalized particles increased by 25-35% as a result of the binding of the antibodies, measured by changes in the susceptibility in an alternating magnetic field. The method has shown high sensitivity, with detection limit of 0.05 microg x mL(-1) of antibody in the biological samples without any pretreatment. This magnetic-based assay is very sensitive, cost-efficient, and versatile, giving a direct indication whether the animal is infected or not, making it suitable for point-of-care applications. The functionalization of tailored magnetic nanoparticles can be modified to suit numerous homogeneous assays for a wide range of applications. PMID:18754596

  8. Novel Accurate and Fast Optic Disc Detection in Retinal Images With Vessel Distribution and Directional Characteristics.

    PubMed

    Zhang, Dongbo; Zhao, Yuanyuan

    2016-01-01

    A novel accurate and fast optic disc (OD) detection method is proposed by using vessel distribution and directional characteristics. A feature combining three vessel distribution characteristics, i.e., local vessel density, compactness, and uniformity, is designed to find possible horizontal coordinate of OD. Then, according to the global vessel direction characteristic, a General Hough Transformation is introduced to identify the vertical coordinate of OD. By confining the possible OD vertical range and by simplifying vessel structure with blocks, we greatly decrease the computational cost of the algorithm. Four public datasets have been tested. The OD localization accuracy lies from 93.8% to 99.7%, when 8-20% vessel detection results are adopted to achieve OD detection. Average computation times for STARE images are about 3.4-11.5 s, which relate to image size. The proposed method shows satisfactory robustness on both normal and diseased images. It is better than many previous methods with respect to accuracy and efficiency.

  9. Performance of a direct detection camera for off-axis electron holography.

    PubMed

    Chang, Shery L Y; Dwyer, Christian; Barthel, Juri; Boothroyd, Chris B; Dunin-Borkowski, Rafal E

    2016-02-01

    The performance of a direct detection camera (DDC) is evaluated in the context of off-axis electron holographic experiments in a transmission electron microscope. Its performance is also compared directly with that of a conventional charge-coupled device (CCD) camera. The DDC evaluated here can be operated either by the detection of individual electron events (counting mode) or by the effective integration of many such events during a given exposure time (linear mode). It is demonstrated that the improved modulation transfer functions and detective quantum efficiencies of both modes of the DDC give rise to significant benefits over the conventional CCD cameras, specifically, a significant improvement in the visibility of the holographic fringes and a reduction of the statistical error in the phase of the reconstructed electron wave function. The DDC's linear mode, which can handle higher dose rates, allows optimisation of the dose rate to achieve the best phase resolution for a wide variety of experimental conditions. For suitable conditions, the counting mode can potentially utilise a significantly lower dose to achieve a phase resolution that is comparable to that achieved using the linear mode. The use of multiple holograms and correlation techniques to increase the total dose in counting mode is also demonstrated. PMID:26630072

  10. Rapid determination of nonaromatic organic acids in honey by capillary zone electrophoresis with direct ultraviolet detection.

    PubMed

    Mato, Inés; Huidobro, José F; Simal-Lozano, Jesús; Sancho, M Teresa

    2006-03-01

    A rapid capillary zone electrophoresis (CZE) method with direct ultraviolet (UV) detection has been set up and developed to determine the most important nonaromatic organic acids in honey with a really simple treatment of the sample. The determination of oxalic, formic, malic, succinic, pyruvic, acetic, lactic, citric, and gluconic acids has been carried out in 4 min. The electrolyte composition was phosphate as the carrier buffer (7.5 mM NaH(2)PO(4) and 2.5 mM Na(2)HPO(4)), 2.5 mM tetradecyltrimethylammonium hydroxide (TTAOH) as electroosmotic flow modifier, and 0.24 mM CaCl(2) as selectivity modifier, with the pH adjusted at 6.40 constant value. The running voltage was -25 kV at a thermostated temperature of 25 degrees C. The injections were performed in hydrodynamic mode (30 s), and the detection mode was UV direct at 185 nm. Validation parameters of the method as detection and quantification limits, linearity, precision (repeatability and reproducibility), and recovery were also studied. The advantages related to the technique such as simplicity, short analysis times, and low consumption of chemicals as well as the good validation parameters obtained for this method permit it to be considered as adequate for routine analysis in honey.

  11. Text line detection based on cost optimized local text line direction estimation

    NASA Astrophysics Data System (ADS)

    Guo, Yandong; Sun, Yufang; Bauer, Peter; Allebach, Jan P.; Bouman, Charles A.

    2015-01-01

    Text line detection is a critical step for applications in document image processing. In this paper, we propose a novel text line detection method. First, the connected components are extracted from the image as symbols. Then, we estimate the direction of the text line in multiple local regions. This estimation is, for the first time, to our knowledge, formulated in a cost optimization framework. We also propose an efficient way to solve this optimization problem. Afterwards, we consider symbols as nodes in a graph, and connect symbols based on the local text line direction estimation results. Last, we detect the text lines by separating the graph into subgraphs according to the nodes' connectivities. Preliminary experimental results demonstrate that our proposed method is very robust to non-uniform skew within text lines, variability of font sizes, and complex structures of layout. Our new method works well for documents captured with flat-bed and sheet-fed scanners, mobile phone cameras, and with other general imaging assets.

  12. Sensitive and rapid detection of Chlamydia trachomatis by recombinase polymerase amplification directly from urine samples.

    PubMed

    Krõlov, Katrin; Frolova, Jekaterina; Tudoran, Oana; Suhorutsenko, Julia; Lehto, Taavi; Sibul, Hiljar; Mäger, Imre; Laanpere, Made; Tulp, Indrek; Langel, Ülo

    2014-01-01

    Chlamydia trachomatis is the most common sexually transmitted human pathogen. Infection results in minimal to no symptoms in approximately two-thirds of women and therefore often goes undiagnosed. C. trachomatis infections are a major public health concern because of the potential severe long-term consequences, including an increased risk of ectopic pregnancy, chronic pelvic pain, and infertility. To date, several point-of-care tests have been developed for C. trachomatis diagnostics. Although many of them are fast and specific, they lack the required sensitivity for large-scale application. We describe a rapid and sensitive form of detection directly from urine samples. The assay uses recombinase polymerase amplification and has a minimum detection limit of 5 to 12 pathogens per test. Furthermore, it enables detection within 20 minutes directly from urine samples without DNA purification before the amplification reaction. Initial analysis of the assay from clinical patient samples had a specificity of 100% (95% CI, 92%-100%) and a sensitivity of 83% (95% CI, 51%-97%). The whole procedure is fairly simple and does not require specific machinery, making it potentially applicable in point-of-care settings.

  13. Assessing the sensitivity of diffusion MRI to detect neuronal activity directly.

    PubMed

    Bai, Ruiliang; Stewart, Craig V; Plenz, Dietmar; Basser, Peter J

    2016-03-22

    Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity.

  14. Assessing the sensitivity of diffusion MRI to detect neuronal activity directly

    PubMed Central

    Bai, Ruiliang; Stewart, Craig V.; Plenz, Dietmar; Basser, Peter J.

    2016-01-01

    Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity. PMID:26941239

  15. Constraints on Extrasolar Planet Populations from VLT NACO/SDI and MMT SDI and Direct Adaptive Optics Imaging Surveys: Giant Planets are Rare at Large Separations

    NASA Astrophysics Data System (ADS)

    Nielsen, Eric L.; Close, Laird M.; Biller, Beth A.; Masciadri, Elena; Lenzen, Rainer

    2008-02-01

    We examine the implications for the distribution of extrasolar planets based on the null results from two of the largest direct imaging surveys published to date. Combining the measured contrast curves from 22 of the stars observed with the VLT NACO adaptive optics system by Masciadri and coworkers and 48 of the stars observed with the VLT NACO SDI and MMT SDI devices by Biller and coworkers (for a total of 60 unique stars), we consider what distributions of planet masses and semimajor axes can be ruled out by these data, based on Monte Carlo simulations of planet populations. We can set the following upper limit with 95% confidence: the fraction of stars with planets with semimajor axis between 20 and 100 AU, and mass above 4 MJup, is 20% or less. Also, with a distribution of planet mass of dN/dM propto M-1.16 in the range of 0.5-13 MJup, we can rule out a power-law distribution for semimajor axis (dN/da propto aα) with index 0 and upper cutoff of 18 AU, and index -0.5 with an upper cutoff of 48 AU. For the distribution suggested by Cumming et al., a power-law of index -0.61, we can place an upper limit of 75 AU on the semimajor axis distribution. In general, we find that even null results from direct imaging surveys are very powerful in constraining the distributions of giant planets (0.5-13 MJup) at large separations, but more work needs to be done to close the gap between planets that can be detected by direct imaging, and those to which the radial velocity method is sensitive.

  16. Direct Detection of Burkholderia cepacia in Susceptible Pharmaceutical Products Using Semi-Nested PCR.

    PubMed

    Attia, Mohamed A; Ali, Amal E; Essam, Tamer M; Amin, Magdy A

    2016-01-01

    Burkholderia cepaciahas recently received a considerable attention as one of the major risks in susceptible pharmaceutical products. This microorganism can easily propagate and cause vast and severe contamination, especially to the water supplies for pharmaceutical companies. Moreover, it proliferates within the products and can cause severe infections for humans. Therefore, fast and sensitive detection of these bacteria is of a great demand. The present study introduces improved application of a polymerase chain reaction assay with relatively high sensitivity and specificity for the direct detection ofB. cepaciafrom the aqueous pharmaceutical products. A semi-nested polymerase chain reaction approach using the primer set BCR1/BCR2 followed by BCR1/Mr yielding a 465 bp fragment of the recA gene was applied and tested using both crude lysate from isolated colonies and DNA directly extracted from artificially prepared and spiked reference syrup. The polymerase chain reaction assay showed no interference with other bacterial reference and environmental strains tested, includingStaphylococcus aureusATCC® 6538,Pseudomonas aeruginosaATCC® 9027,Escherichia coliATCC® 8739,Salmonella abonyNCTC® 6017,Bacillus subtilisATCC® 6633,Micrococcus luteus, Staphylococcus warneri, Pseudomonas fluorescens, Pseudomonas putida, andRalstonia pickettii Moreover, this semi-nested assay showed a detection limit of around 10 colony-forming units per sample and could detectB. cepaciastrains isolated from a municipal pre-treated potable water tank. Comparing the results for detection ofB. cepaciain 100 randomly collected commercial syrup preparations using both conventional standard method and polymerase chain reaction assay revealed thatB. cepaciawas detected in two samples using polymerase chain reaction assay while all samples showed negative results by conventional culturing and biochemical methods. These results highlight the advantage of using this polymerase chain reaction assay to

  17. 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

  18. Direct detection of OTA by impedimetric aptasensor based on modified polypyrrole-dendrimers.

    PubMed

    Mejri-Omrani, Nawel; Miodek, Anna; Zribi, Becem; Marrakchi, Mouna; Hamdi, Moktar; Marty, Jean-Louis; Korri-Youssoufi, Hafsa

    2016-05-12

    Ochratoxin A (OTA) is a carcinogenic mycotoxin that contaminates food such as cereals, wine and beer; therefore it represents a risk for human health. Consequently, the allowed concentration of OTA in food is regulated by governmental organizations and its detection is of major agronomical interest. In the current study we report the development of an electrochemical aptasensor able to directly detect trace OTA without any amplification procedure. This aptasensor was constructed by coating the surface of a gold electrode with a film layer of modified polypyrrole (PPy), which was thereafter covalently bound to polyamidoamine dendrimers of the fourth generation (PAMAM G4). Finally, DNA aptamers that specifically binds OTA were covalently bound to the PAMAM G4 providing the aptasensor, which was characterized by using both Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques. The study of OTA detection by the constructed electrochemical aptasensor was performed using Electrochemical Impedance Spectroscopy (EIS) and revealed that the presence of OTA led to the modification of the electrical properties of the PPy layer. These modifications could be assigned to conformational changes in the folding of the aptamers upon specific binding of OTA. The aptasensor had a dynamic range of up to 5 μg L(-1) of OTA and a detection limit of 2 ng L(-1) of OTA, which is below the OTA concentration allowed in food by the European regulations. The efficient detection of OTA by this electrochemical aptasensor provides an unforeseen platform that could be used for the detection of various small molecules through specific aptamer association.

  19. Nested PCR detection of malaria directly using blood filter paper samples from epidemiological surveys

    PubMed Central

    2014-01-01

    Background Nested PCR is considered a sensitive and specific method for detecting malaria parasites and is especially useful in epidemiological surveys. However, the preparation of DNA templates for PCR is often time-consuming and costly. Methods A simplified PCR method was developed to directly use a small blood filter paper square (2 × 2 mm) as the DNA template after treatment with saponin. This filter paper-based nested PCR method (FP-PCR) was compared to microscopy and standard nested PCR with DNA extracted by using a Qiagen DNA mini kit from filter paper blood spots of 204 febrile cases. The FP-PCR technique was further applied to evaluate malaria infections in 1,708 participants from cross-sectional epidemiological surveys conducted in Myanmar and Thailand. Results The FP-PCR method had a detection limit of ~0.2 parasites/μL blood, estimated using cultured Plasmodium falciparum parasites. With 204 field samples, the sensitivity of the FP-PCR method was comparable to that of the standard nested PCR method, which was significantly higher than that of microscopy. Application of the FP-PCR method in large cross-sectional studies conducted in Myanmar and Thailand detected 1.9% (12/638) and 6.2% (66/1,070) asymptomatic Plasmodium infections, respectively, as compared to the detection rates of 1.3% (8/638) and 0.04% (4/1,070) by microscopy. Conclusion This FP-PCR method was much more sensitive than microscopy in detecting Plasmodium infections. It drastically increased the detection sensitivity of asymptomatic infections in cross-sectional surveys conducted in Thailand and Myanmar, suggesting that this FP-PCR method has a potential for future applications in malaria epidemiology studies. PMID:24884761

  20. Direct detection of OTA by impedimetric aptasensor based on modified polypyrrole-dendrimers.

    PubMed

    Mejri-Omrani, Nawel; Miodek, Anna; Zribi, Becem; Marrakchi, Mouna; Hamdi, Moktar; Marty, Jean-Louis; Korri-Youssoufi, Hafsa

    2016-05-12

    Ochratoxin A (OTA) is a carcinogenic mycotoxin that contaminates food such as cereals, wine and beer; therefore it represents a risk for human health. Consequently, the allowed concentration of OTA in food is regulated by governmental organizations and its detection is of major agronomical interest. In the current study we report the development of an electrochemical aptasensor able to directly detect trace OTA without any amplification procedure. This aptasensor was constructed by coating the surface of a gold electrode with a film layer of modified polypyrrole (PPy), which was thereafter covalently bound to polyamidoamine dendrimers of the fourth generation (PAMAM G4). Finally, DNA aptamers that specifically binds OTA were covalently bound to the PAMAM G4 providing the aptasensor, which was characterized by using both Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques. The study of OTA detection by the constructed electrochemical aptasensor was performed using Electrochemical Impedance Spectroscopy (EIS) and revealed that the presence of OTA led to the modification of the electrical properties of the PPy layer. These modifications could be assigned to conformational changes in the folding of the aptamers upon specific binding of OTA. The aptasensor had a dynamic range of up to 5 μg L(-1) of OTA and a detection limit of 2 ng L(-1) of OTA, which is below the OTA concentration allowed in food by the European regulations. The efficient detection of OTA by this electrochemical aptasensor provides an unforeseen platform that could be used for the detection of various small molecules through specific aptamer association. PMID:27114221

  1. A direct detection of Escherichia coli genomic DNA using gold nanoprobes

    PubMed Central

    2012-01-01

    Background In situation like diagnosis of clinical and forensic samples there exists a need for highly sensitive, rapid and specific DNA detection methods. Though conventional DNA amplification using PCR can provide fast results, it is not widely practised in diagnostic laboratories partially because it requires skilled personnel and expensive equipment. To overcome these limitations nanoparticles have been explored as signalling probes for ultrasensitive DNA detection that can be used in field applications. Among the nanomaterials, gold nanoparticles (AuNPs) have been extensively used mainly because of its optical property and ability to get functionalized with a variety of biomolecules. Results We report a protocol for the use of gold nanoparticles functionalized with single stranded oligonucleotide (AuNP- oligo probe) as visual detection probes for rapid and specific detection of Escherichia coli. The AuNP- oligo probe on hybridization with target DNA containing complementary sequences remains red whereas test samples without complementary DNA sequences to the probe turns purple due to acid induced aggregation of AuNP- oligo probes. The color change of the solution is observed visually by naked eye demonstrating direct and rapid detection of the pathogenic Escherichia coli from its genomic DNA without the need for PCR amplification. The limit of detection was ~54 ng for unamplified genomic DNA. The method requires less than 30 minutes to complete after genomic DNA extraction. However, by using unamplified enzymatic digested genomic DNA, the detection limit of 11.4 ng was attained. Results of UV-Vis spectroscopic measurement and AFM imaging further support the hypothesis of aggregation based visual discrimination. To elucidate its utility in medical diagnostic, the assay was validated on clinical strains of pathogenic Escherichia coli obtained from local hospitals and spiked urine samples. It was found to be 100% sensitive and proves to be highly specific without

  2. Protein, carbohydrate, lipid concentrations and HSP 70-HSP 90 (stress protein) expression over an annual cycle: useful tools to detect feeding constraints in a benthic suspension feeder

    NASA Astrophysics Data System (ADS)

    Rossi, Sergio; Snyder, Mark J.; Gili, Josep-Marìa

    2006-03-01

    In the present paper we suggest an effect of seasonal variations in food availability on two ecophysiological parameters in a warm temperate benthic suspension feeder: the tissue concentrations of proteins, carbohydrates and lipids on the one hand, and the expression of stress proteins (HSP 70 and 90, inducible and/or constitutive) on the other hand. The concentrations of biomacromolecules have already been used to describe bentho-pelagic and reproductive processes, but this is the first time that stress protein expression is suggested to be directly related with food constraints in marine organisms. Paramuricea clavata (Cnidaria: Gorgonacea) express HSP 70 and 90 (constitutive and/or inducible) throughout the seasonal cycle, and HSP 70 levels are twice as high as the levels of HSP 90. In summer and autumn, when seston availability to suspension feeders was low, P. clavata showed low levels of carbohydrates and lipids, but high levels of HSPs expression. The levels of HSP 70 and 90 expression fit with negative exponential functions of carbohydrate and lipid concentrations. We suggest a direct effect of food availability on the studied ecophysiological parameters while the effect of temperature may be rather indirect. HSP expression as well as the tissue concentrations of carbohydrate and lipids may be used as biomarkers of environmental changes and seston availability to benthic suspension feeders.

  3. Quantitative direct probe method for the detection of parvovirus B19.

    PubMed

    Boggino, H; Payne, D A

    2000-01-01

    Parvovirus B19 infection is associated with anemia and spontaneous abortions. While many qualitative assays are available, a few molecular-based quantitative methods have been described. This study reports the development and optimization of a quantitative direct-probe method for the detection of Parvovirus B19 DNA. Different concentrations of RNA probes were used to identify the optimal conditions for hybridizing to the target DNA. Detection of DNA was linear between concentrations of 2 ng/ml to 200 pg/ml. Because this method requires no enzymatic amplification, it is not susceptible to amplifier contamination or enzymatic inhibitors, and it can be applied to serum samples or paraffin-embedded tissue.

  4. Direct detection of lower hybrid wave using a reflectometer on Alcator C-Moda)

    NASA Astrophysics Data System (ADS)

    Shiraiwa, S.; Baek, S.; Dominguez, A.; Marmar, E.; Parker, R.; Kramer, G. J.

    2010-10-01

    The possibility of directly detecting a density perturbation produced by lower hybrid (LH) waves using a reflectometer is presented. We investigate the microwave scattering of reflectometer probe beams by a model density fluctuation produced by short wavelength LH waves in an Alcator C-Mod experimental condition. In the O-mode case, the maximum response of phase measurement is found to occur when the density perturbation is approximately centimeters in front of the antenna, where Bragg scattering condition is satisfied. In the X-mode case, the phase measurement is predicted to be more sensitive to the density fluctuation close to the cut-off layer. A feasibility test was carried out using a 50 GHz O-mode reflectometer on the Alcator C-Mod tokamak, and positive results including the detection of 4.6 GHz pump wave and parametric decay instabilities were obtained.

  5. Characterization and quantification in capillary zone electrophoresis using direct and indirect detection

    SciTech Connect

    Chiang, Hui-Ti; Church, W.H.

    1995-12-01

    Capillary zone electrophoresis has become a major separation technique for the analysis of small volumes of materials and it is featured with the advantages of high efficiency, simplicity and rapidity. The purpose of this study was to characterize the performance of a capillary electrophoresis system in regards to the separation efficiency and quantitative capacity. Three sample introduction techniques--electromigration, gravity and pressure injection modes--were evaluated utilizing two different sample-buffer systems. Analytes phenol, benzoic acid and 2,4-dihydroxybenzoic acid were separated underpositive polarity voltage using a borate buffet and monitored with direct UV absorption detection. Mixtures of myo-inositol 2-monophosphate, myo-inositol 1,4,5-trisphosphate, and myo-inositol hexakisphosphate were separated under negative polarity voltage using a lon Phor Anionic Electrolyte Buffer containing an electroosmotic flow modifier and a background chromophore for indirect detection.

  6. 50 Mbps free space direct detection laser diode optical communication system with Q = 4 PPM signaling

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Davidson, Frederic; Field, Christopher

    1990-01-01

    A 50 Mbps direct detection optical communication system for use in an intersatellite link was constructed with an AlGaAs laser diode transmitter and a silicon avalanche photodiode photodetector. The system used a Q = 4 PPM format. The receiver consisted of a maximum likelihood PPM detector and a timing recovery subsystem. The PPM slot clock was recovered at the receiver by using a transition detector followed by a PLL. The PPM word clock was recovered by using a second PLL whose input was derived from the presence of back-to-back PPM pulses contained in the received random PPM pulse sequences. The system achieved a bit error rate of 0.000001 at less than 50 detected signal photons/information bit. The receiver was capable of acquiring and maintaining slot and word synchronization for received signal levels greater than 20 photons/information bit, at which the receiver bit error rate was about 0.01.

  7. Quantitative direct probe method for the detection of parvovirus B19.

    PubMed

    Boggino, H; Payne, D A

    2000-01-01

    Parvovirus B19 infection is associated with anemia and spontaneous abortions. While many qualitative assays are available, a few molecular-based quantitative methods have been described. This study reports the development and optimization of a quantitative direct-probe method for the detection of Parvovirus B19 DNA. Different concentrations of RNA probes were used to identify the optimal conditions for hybridizing to the target DNA. Detection of DNA was linear between concentrations of 2 ng/ml to 200 pg/ml. Because this method requires no enzymatic amplification, it is not susceptible to amplifier contamination or enzymatic inhibitors, and it can be applied to serum samples or paraffin-embedded tissue. PMID:10645984

  8. Direct detection of singlet dark matter in classically scale-invariant standard model

    NASA Astrophysics Data System (ADS)

    Endo, Kazuhiro; Ishiwata, Koji

    2015-10-01

    Classical scale invariance is one of the possible solutions to explain the origin of the electroweak scale. The simplest extension is the classically scale-invariant standard model augmented by a multiplet of gauge singlet real scalar. In the previous study it was shown that the properties of the Higgs potential deviate substantially, which can be observed in the International Linear Collider. On the other hand, since the multiplet does not acquire vacuum expectation value, the singlet components are stable and can be dark matter. In this letter we study the detectability of the real singlet scalar bosons in the experiment of the direct detection of dark matter. It is shown that a part of this model has already been excluded and the rest of the parameter space is within the reach of the future experiment.

  9. Direct detection of x-rays for protein crystallography employing a thick, large area CCD

    DOEpatents

    Atac, Muzaffer; McKay, Timothy

    1999-01-01

    An apparatus and method for directly determining the crystalline structure of a protein crystal. The crystal is irradiated by a finely collimated x-ray beam. The interaction of the x-ray beam with the crystal produces scattered x-rays. These scattered x-rays are detected by means of a large area, thick CCD which is capable of measuring a significant number of scattered x-rays which impact its surface. The CCD is capable of detecting the position of impact of the scattered x-ray on the surface of the CCD and the quantity of scattered x-rays which impact the same cell or pixel. This data is then processed in real-time and the processed data is outputted to produce a image of the structure of the crystal. If this crystal is a protein the molecular structure of the protein can be determined from the data received.

  10. Design and Development of a Scanning Airborne Direct Detection Doppler Lidar System

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce; McGill, Matthew; Schwemmer, Geary; Hardesty, Michael; Brewer, Alan; Wilkerson, Thomas; Atlas, Robert; Sirota, Marcos; Lindemann, Scott

    2006-01-01

    In the fall of 2005 we began developing an airborne scanning direct detection molecular Doppler lidar. The instrument is being built as part of the Tropospheric Wind Lidar Technology Experiment (TWiLiTE), a three year project selected by the NASA Earth Sun Technology Office under the Instrument Incubator Program. The TWiLiTE project is a collaboration involving scientists and engineers from NASA Goddard Space Flight Center, NOAA ESRL, Utah State University Space Dynamics Lab, Michigan Aerospace Corporation and Sigma Space Corporation. The TWiLiTE instrument will leverage significant research and development investments made by NASA Goddard and it's partners in the past several years in key lidar technologies and sub-systems (lasers, telescopes, scanning systems, detectors and receivers) required to enable spaceborne global wind lidar measurement. These sub-systems will be integrated into a complete molecular direct detection Doppler wind lidar system designed for autonomous operation on a high altitude aircraft, such as the NASA WB57. The WB57 flies at an altitude of 18 km and from this vantage point the nadir viewing Doppler lidar will be able to profile winds through the full troposphere. The TWiLiTE integrated airborne Doppler lidar instrument will be the first demonstration of a airborne scanning direct detection Doppler lidar and will serve as a critical milestone on the path to a future spaceborne tropospheric wind system. In addition to being a technology testbed for space based tropospheric wind lidar, when completed the TWiLiTE high altitude airborne lidar will be used for studying mesoscale dynamics and storm research (e.g. winter storms, hurricanes) and could be used for calibration and validation of satellite based wind systems such as ESA's Aeolus Atmospheric Dynamics Mission. The TWiLiTE Doppler lidar will have the capability to profile winds in clear air from the aircraft altitude of 18 km to the surface with 250 m vertical resolution and < 2mls

  11. The impact of baryons on the direct detection of dark matter

    NASA Astrophysics Data System (ADS)

    Kelso, Chris; Savage, Christopher; Valluri, Monica; Freese, Katherine; Stinson, Gregory S.; Bailin, Jeremy

    2016-08-01

    The spatial and velocity distributions of dark matter particles in the Milky Way Halo affect the signals expected to be observed in searches for dark matter. Results from direct detection experiments are often analyzed assuming a simple isothermal distribution of dark matter, the Standard Halo Model (SHM). Yet there has been skepticism regarding the validity of this simple model due to the complicated gravitational collapse and merger history of actual galaxies. In this paper we compare the SHM to the results of cosmological hydrodynamical simulations of galaxy formation to investigate whether or not the SHM is a good representation of the true WIMP distribution in the analysis of direct detection data. We examine two Milky Way-like galaxies from the MaGICC cosmological simulations (a) with dark matter only and (b) with baryonic physics included. The inclusion of baryons drives the shape of the DM halo to become more spherical and makes the velocity distribution of dark matter particles less anisotropic especially at large heliocentric velocities, thereby making the SHM a better fit. We also note that we do not find a significant disk-like rotating dark matter component in either of the two galaxy halos with baryons that we examine, suggesting that dark disks are not a generic prediction of cosmological hydrodynamical simulations. We conclude that in the Solar neighborhood, the SHM is in fact a good approximation to the true dark matter distribution in these cosmological simulations (with baryons) which are reasonable representations of the Milky Way, and hence can also be used for the purpose of dark matter direct detection calculations.

  12. Direct Measurement of Mammographic X-Ray Spectra with a Digital CdTe Detection System

    PubMed Central

    Abbene, Leonardo; Gerardi, Gaetano; Principato, Fabio; Sordo, Stefano Del; Raso, Giuseppe

    2012-01-01

    In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate X-ray spectroscopy in mammography (1–30 keV). The DPP system performs a height and shape analysis of the detector pulses, sampled and digitized by a 14-bit, 100 MHz ADC. We show the results of the characterization of the detection system both at low and high photon counting rates by using monoenergetic X-ray sources and a nonclinical X-ray tube. The detection system exhibits excellent performance up to 830 kcps with an energy resolution of 4.5% FWHM at 22.1 keV. Direct measurements of clinical molybdenum X-ray spectra were carried out by using a pinhole collimator and a custom alignment device. A comparison with the attenuation curves and the half value layer values, obtained from the measured and simulated spectra, from an ionization chamber and from a solid state dosimeter, also shows the accuracy of the measurements. These results make the proposed detection system a very attractive tool for both laboratory research, calibration of dosimeters and advanced quality controls in mammography. PMID:22969406

  13. Assessment of absolute added correlative coding in optical intensity modulation and direct detection channels

    NASA Astrophysics Data System (ADS)

    Dong-Nhat, Nguyen; Elsherif, Mohamed A.; Malekmohammadi, Amin

    2016-06-01

    The performance of absolute added correlative coding (AACC) modulation format with direct detection has been numerically and analytically reported, targeting metro data center interconnects. Hereby, the focus lies on the performance of the bit error rate, noise contributions, spectral efficiency, and chromatic dispersion tolerance. The signal space model of AACC, where the average electrical and optical power expressions are derived for the first time, is also delineated. The proposed modulation format was also compared to other well-known signaling, such as on-off-keying (OOK) and four-level pulse-amplitude modulation, at the same bit rate in a directly modulated vertical-cavity surface-emitting laser-based transmission system. The comparison results show a clear advantage of AACC in achieving longer fiber delivery distance due to the higher dispersion tolerance.

  14. In-line interferometer for direction-sensitive displacement measurements by optical feedback detection

    SciTech Connect

    Tarun, Alvarado; Jecong, Julius; Saloma, Caesar

    2005-12-01

    We demonstrate a compact in-line interferometer for direction-sensitive displacement measurement by optical feedback detection with a semiconductor laser (SL) light source. Two reflected beams from a semitransparent reference mirror and a reflecting test object interfere in the SL medium, causing a variation in its output power. The reference mirror is located between the SL output facet and the test object. The performance of the interferometer is investigated numerically and experimentally to determine its optimal operating conditions. We have verified the operating conditions where the behavior of the SL output power profile could indicate accurately the displacement magnitude and direction of the moving test object. The profile behavior is robust against variations in optical feedback and scale of the interferometer configuration.

  15. Low energy electron/recoil discrimination for directional Dark Matter detection

    SciTech Connect

    Billard, J.; Mayet, F.; Santos, D. E-mail: mayet@lpsc.in2p3.fr

    2012-07-01

    Directional detection is a promising Dark Matter search strategy. Even though it could accommodate to a sizeable background contamination, electron/recoil discrimination remains a key and challenging issue as for direction-insensitive detectors. The measurement of the 3D track may be used to discriminate electrons from nuclear recoils. While a high rejection power is expected above 20 keV ionization, a dedicated data analysis is needed at low energy. After identifying discriminant observables, a multivariate analysis, namely a Boosted Decision Tree, is proposed, enabling an efficient event tagging for Dark Matter search. We show that it allows us to optimize rejection while keeping a rather high efficiency which is compulsory for rare event search.With respect to a sequential analysis, the rejection is about ∼ 20 times higher with a multivariate analysis, for the same Dark Matter exclusion limit.

  16. Direct growth of graphene on quartz substrates for label-free detection of adenosine triphosphate.

    PubMed

    Xu, Shicai; Man, Baoyuan; Jiang, Shouzhen; Yue, Weiwei; Yang, Cheng; Liu, Mei; Chen, Chuansong; Zhang, Chao

    2014-04-25

    We demonstrate that continuous, uniform graphene films can be directly synthesized on quartz substrates using a two-temperature-zone chemical vapor deposition system and that their layers can be controlled by adjusting the precursor partial pressure. Raman spectroscopy and transmission electron microscopy confirm the formation of monolayer graphene with a grain size of ∼100 nm. Hall measurements show a room-temperature carrier mobility above 1500 cm2 V(-1) s(-1). The optical transmittance and conductance of the graphene films are comparable to those of transferred metal-catalyzed graphene. The method avoids the complicated and skilled post-growth transfer process and allows the graphene to be directly incorporated into a fully functional biosensor for label-free detection of adenosine triphosphate (ATP). This device shows a fast response time of a few milliseconds and achieves a high sensitivity to ATP molecules over a very wide range from 0.002 to 5 mM. PMID:24671026

  17. Direct colony PCR-SSCP for detection of multiple pythiaceous oomycetes in environmental samples.

    PubMed

    Kong, Ping; Richardson, Patricia A; Hong, Chuanxue

    2005-04-01

    Colony PCR was developed for detection of pythiaceous species recovered on selective agar plates without DNA extraction. A minute amount of mycelia from a single colony was picked up with a pipette tip and added directly to the PCR mix as template for DNA amplification. Successful amplification was achieved in over 95% of the colonies recovered from plant tissues, irrigation water and soil with species-specific primers or oomycete ITS-1 primers. PCR was inhibited in the case of colonies emerging from unwashed pine bark potting mix plates. Direct colony PCR with ITS-1 primers combined with single-strand conformation polymorphism analysis (SSCP) was used to determine population levels of single and multiple species in plant and environmental samples. Application of this technique for disease diagnosis and monitoring pathogen sources was explored, and the potential for studying diversity and population dynamics of other cultivated microbial communities in the environment is discussed. PMID:15676193

  18. Detecting direct collapse black holes: making the case for CR7

    NASA Astrophysics Data System (ADS)

    Agarwal, Bhaskar; Johnson, Jarrett L.; Zackrisson, Erik; Labbe, Ivo; van den Bosch, Frank C.; Natarajan, Priyamvada; Khochfar, Sadegh

    2016-08-01

    We propose that one of the sources in the recently detected system CR7 by Sobral et al. through spectrophotometric measurements at z = 6.6 harbours a direct collapse black hole (DCBH). We argue that the LW radiation field required for direct collapse in source A is provided by sources B and C. By tracing the LW production history and star formation rate over cosmic time for the halo hosting CR7 in a ΛCDM universe, we demonstrate that a DCBH could have formed at z ˜ 20. The spectrum of source A is well fit by nebular emission from primordial gas around a BH with MBH ˜4.4 × 106 M⊙ accreting at a 40 per cent of the Eddington rate, which strongly supports our interpretation of the data. Combining these lines of evidence, we argue that CR7 might well be the first DCBH candidate.

  19. Direct growth of graphene on quartz substrates for label-free detection of adenosine triphosphate.

    PubMed

    Xu, Shicai; Man, Baoyuan; Jiang, Shouzhen; Yue, Weiwei; Yang, Cheng; Liu, Mei; Chen, Chuansong; Zhang, Chao

    2014-04-25

    We demonstrate that continuous, uniform graphene films can be directly synthesized on quartz substrates using a two-temperature-zone chemical vapor deposition system and that their layers can be controlled by adjusting the precursor partial pressure. Raman spectroscopy and transmission electron microscopy confirm the formation of monolayer graphene with a grain size of ∼100 nm. Hall measurements show a room-temperature carrier mobility above 1500 cm2 V(-1) s(-1). The optical transmittance and conductance of the graphene films are comparable to those of transferred metal-catalyzed graphene. The method avoids the complicated and skilled post-growth transfer process and allows the graphene to be directly incorporated into a fully functional biosensor for label-free detection of adenosine triphosphate (ATP). This device shows a fast response time of a few milliseconds and achieves a high sensitivity to ATP molecules over a very wide range from 0.002 to 5 mM.

  20. Multi-Dimensional Effective Field Theory Analysis for Direct Detection of Dark Matter

    NASA Astrophysics Data System (ADS)

    Rogers, Hannah; SuperCDMS Collaboration

    2016-03-01

    Experiments like the Cryogenic Dark Matter Search (CDMS) attempt to find dark matter (non-luminous matter that makes up approximately 80% of the matter in the universe) through direct detection of interactions between dark matter and a target material. The Effective Field Theory (EFT) approach increases the number of considered interactions between dark matter and the normal, target matter from two (spin independent and spin dependent interactions) to eleven operators with four possible interference terms. These additional operators allow for a more complete analysis of complimentary direct dark matter searches; however, the higher dimensional likelihoods necessary to span an increase in operators requires a clever computational tool such as MultiNest. I present here analyses of published and projected data from CDMS (Si and Ge targets) and LUX (liquid Xe target) assuming operator parameter spaces ranging from 3 - 5 dimensions and folding in information on energy-dependent backgrounds when possible.

  1. Rapid detection of NBOME's and other NPS on blotter papers by direct ATR-FTIR spectrometry.

    PubMed

    Coelho Neto, José

    2015-07-01

    Blotter paper is among the most common forms of consumption of new psychotropic substances (NPS), formerly referred as designer drugs. In many cases, users are misled to believe they are taking LSD when, in fact, they are taking newer and less known drugs like the NBOMEs or other substituted phenethylamines. We report our findings in quick testing of blotter papers for illicit substances like NBOMEs and other NPS by taking ATR-FTIR spectra directly from blotters seized on the streets, without any sample preparation. Both sides (front and back) of each blotter were tested. Collected data were analyzed by single- and multi-component spectral matching and submitted to chemometric discriminant analysis. Our results showed that, on 66.7% of the cases analyzed, seized blotters contained one or more types of NBOMEs, confirming the growing presence of this novel substances on the market. Matching IR signals were detected on both or just one side of the blotters and showed variable strength. Although no quantitative analysis was made, detection of these substances by the proposed approach serves as indication of variable and possibly higher dosages per blotter when compared to LSD, which showed to be below the detection limit of the applied method. Blotters containing a mescaline-like compound, later confirmed by GC-MS and LC-MS to be MAL (methallylescaline), a substance very similar to mescaline, were detected among the samples tested. Validity of direct ATR-FTIR testing was confirmed by checking the obtained results against independent GC-MS or LC-MS results for the same cases/samples.

  2. Direct Detection and Quantification of Bacterial Genes Associated with Inflammation in DNA Isolated from Stool

    PubMed Central

    Gómez-Moreno, Ramón; Robledo, Iraida E.; Baerga-Ortiz, Abel

    2014-01-01

    Although predominantly associated with health benefits, the gut microbiota has also been shown to harbor genes that promote inflammation. In this work, we report a method for the direct detection and quantification of these pro-inflammatory bacterial genes by PCR and qPCR in DNA extracted from human stool samples. PCR reactions were performed to detect (i) the pks island genes, (ii) tcpC, which is present in some strains of Escherichia coli and (iii) gelE presented in some strains of Enterococcus faecalis. Additionally, we screened for the presence of the following genes encoding cyclomodulins that disrupted mammalian cell division: (iv) cdt (which encodes the cytolethal distending toxin) and (v) cnf-1 (which encodes the cytotoxic necrotizing factor-1). Our results show that 20% of the samples (N = 41) tested positive for detectable amounts of pks island genes, whereas 10% of individuals were positive for tcpC or gelE and only one individual was found to harbor the cnf-1 gene. Of the 13 individuals that were positive for at least one of the pro-inflammatory genes, 5 were found to harbor more than one. A quantitative version of the assay, which used real-time PCR, revealed the pro-inflammatory genes to be in high copy numbers: up to 1.3 million copies per mg of feces for the pks island genes. Direct detection of specific genes in stool could prove useful toward screening for the presence of pro-inflammatory bacterial genes in individuals with inflammatory bowel diseases or colorectal cancer. PMID:25635239

  3. Passive mass transport for direct and quantitative SERS detection using purified silica encapsulated metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shrestha, Binaya Kumar

    This thesis focuses on understanding implications of nanomaterial quality control and mass transport through internally etched silica coated nanoparticles for direct and quantitative molecular detection using surface enhanced Raman scattering (SERS). Prior to use, bare nanoparticles (partially or uncoated with silica) are removal using column chromatography to improve the quality of these nanomaterials and their SERS reproducibility. Separation of silica coated nanoparticles with two different diameters is achieved using Surfactant-free size exclusion chromatography with modest fractionation. Next, selective molecular transport is modeled and monitored using SERS and evaluated as a function of solution ionic strength, pH, and polarity. Molecular detection is achieved when the analytes first partition through the silica membrane then interact with the metal surface at short distances (i.e., less than 2 nm). The SERS intensities of unique molecular vibrational modes for a given molecule increases as the number of molecules that bind to the metal surface increases and are enhanced via both chemical and electromagnetic enhancement mechanisms as long as the vibrational mode has a component of polarizability tensor along the surface normal. SERS signals increase linearly with molecular concentration until the three-dimensional SERS-active volume is saturated with molecules. Implications of molecular orientation as well as surface selection rules on SERS intensities of molecular vibrational modes are studied to improve quantitative and reproducible SERS detection using internally etched Ag Au SiO2 nanoparticles. Using the unique vibrational modes, SERS intensities for p-aminothiophenol as a function of metal core compositions and plasmonics are studied. By understanding molecular transport mechanisms through internally etched silica matrices coated on metal nanoparticles, important experimental and materials design parameters are learned, which can be subsequently applied

  4. Combined Direct and Indirect CT Venography (Combined CTV) in Detecting Lower Extremity Deep Vein Thrombosis

    PubMed Central

    Shi, Wan-Yin; Wang, Li-Wei; Wang, Shao-Juan; Yin, Xin-Dao; Gu, Jian-Ping

    2016-01-01

    Abstract This study aimed to evaluate the diagnostic accuracy of combined direct and indirect CT venography (combined CTV) in the detection of lower extremity deep vein thrombosis (LEDVT). The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent. A total of 96 consecutive patients undergoing combined CTV were prospectively enrolled. A combined examination with digital subtraction angiography (DSA) plus duplex ultrasonography (US) was used as the criterion standard. Three observers were blinded to clinical, DSA, and US results, and they independently analyzed all combined CTV datasets. Interobserver agreement was expressed in terms of the Cohen k value for categorical variables. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of combined CTV in the detection of LEDVT were determined by using patient- and location-based evaluations. Of the 96 patients, DSA plus US revealed LEDVT in 125 segmental veins in 63 patients. Patient-based evaluation with combined CTV yielded an accuracy of 96.9% to 97.9%, a sensitivity of 95.2% to 96.8%, a specificity of 100% to 100%, a PPV of 100% to 100%, and an NPV of 91.7% to 94.3% in the detection of LEDVT. Location-based evaluation yielded similar results. Through combined direct and indirect CTV, patients obtained a combined CT angiogram on the diseased limb and an indirect CT angiogram on the opposite side. The image quality of combined CTV was superior to an indirect venogram. Combined CTV shows promising diagnostic accuracy in the detection of LEDVT with 3-dimensional modeling of the lower limb venous system. PMID:26986113

  5. Combined Direct and Indirect CT Venography (Combined CTV) in Detecting Lower Extremity Deep Vein Thrombosis.

    PubMed

    Shi, Wan-Yin; Wang, Li-Wei; Wang, Shao-Juan; Yin, Xin-Dao; Gu, Jian-Ping

    2016-03-01

    This study aimed to evaluate the diagnostic accuracy of combined direct and indirect CT venography (combined CTV) in the detection of lower extremity deep vein thrombosis (LEDVT). The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent. A total of 96 consecutive patients undergoing combined CTV were prospectively enrolled. A combined examination with digital subtraction angiography (DSA) plus duplex ultrasonography (US) was used as the criterion standard. Three observers were blinded to clinical, DSA, and US results, and they independently analyzed all combined CTV datasets. Interobserver agreement was expressed in terms of the Cohen k value for categorical variables. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of combined CTV in the detection of LEDVT were determined by using patient- and location-based evaluations. Of the 96 patients, DSA plus US revealed LEDVT in 125 segmental veins in 63 patients. Patient-based evaluation with combined CTV yielded an accuracy of 96.9% to 97.9%, a sensitivity of 95.2% to 96.8%, a specificity of 100% to 100%, a PPV of 100% to 100%, and an NPV of 91.7% to 94.3% in the detection of LEDVT. Location-based evaluation yielded similar results. Through combined direct and indirect CTV, patients obtained a combined CT angiogram on the diseased limb and an indirect CT angiogram on the opposite side. The image quality of combined CTV was superior to an indirect venogram. Combined CTV shows promising diagnostic accuracy in the detection of LEDVT with 3-dimensional modeling of the lower limb venous system.

  6. Combined Direct and Indirect CT Venography (Combined CTV) in Detecting Lower Extremity Deep Vein Thrombosis.

    PubMed

    Shi, Wan-Yin; Wang, Li-Wei; Wang, Shao-Juan; Yin, Xin-Dao; Gu, Jian-Ping

    2016-03-01

    This study aimed to evaluate the diagnostic accuracy of combined direct and indirect CT venography (combined CTV) in the detection of lower extremity deep vein thrombosis (LEDVT). The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent. A total of 96 consecutive patients undergoing combined CTV were prospectively enrolled. A combined examination with digital subtraction angiography (DSA) plus duplex ultrasonography (US) was used as the criterion standard. Three observers were blinded to clinical, DSA, and US results, and they independently analyzed all combined CTV datasets. Interobserver agreement was expressed in terms of the Cohen k value for categorical variables. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of combined CTV in the detection of LEDVT were determined by using patient- and location-based evaluations. Of the 96 patients, DSA plus US revealed LEDVT in 125 segmental veins in 63 patients. Patient-based evaluation with combined CTV yielded an accuracy of 96.9% to 97.9%, a sensitivity of 95.2% to 96.8%, a specificity of 100% to 100%, a PPV of 100% to 100%, and an NPV of 91.7% to 94.3% in the detection of LEDVT. Location-based evaluation yielded similar results. Through combined direct and indirect CTV, patients obtained a combined CT angiogram on the diseased limb and an indirect CT angiogram on the opposite side. The image quality of combined CTV was superior to an indirect venogram. Combined CTV shows promising diagnostic accuracy in the detection of LEDVT with 3-dimensional modeling of the lower limb venous system. PMID:26986113

  7. Direct detection of Tritium and Carbon-14 beta particles with GaAs photodiodes

    NASA Astrophysics Data System (ADS)

    Barnett, A. M.; Lees, J. E.; Bassford, D. J.

    2012-09-01

    New measurements are reported which show beta particles emitted from 3H and 14C sources being directly detected with GaAs mesa photodiodes without use of scintillators. Spectra accumulated with GaAs diodes which were originally developed for X-ray spectroscopy are presented which show that individual beta particles from these sources can be counted and the energy they deposit in the detector measured. Potential longer term applications of this technology as it is developed further and improved include space missions, autoradiography, monitoring tritium produced by fusion reactors and nuclear decommissioning.

  8. Direct detection of spontaneous polarization in wurtzite GaAs nanowires

    SciTech Connect

    Bauer, Benedikt Hubmann, Joachim; Lohr, Matthias; Reiger, Elisabeth; Bougeard, Dominique; Zweck, Josef

    2014-05-26

    We demonstrate the direct detection of spontaneous polarization in the wurtzite crystal phase of gallium-arsenide (GaAs) nanowires. Using differential phase contrast microscopy (DPC) in a scanning transmission electron microscope, we map the differences in charge distribution between the zinc-blende and wurtzite crystal phases and use twin defects in the zinc-blende phase to quantify the polarization strength. The value of 2.7 × 10{sup −3} C/m{sup 2} found for the polarization strength matches well with theoretical predictions.

  9. ISOLATION AND DETECTION OF GIARDIA CYSTS FROM WATER USING DIRECT IMMUNOFLUORESCENCE.

    USGS Publications Warehouse

    Sorenson, Stephen K.; Riggs, John L.; Dileanis, Peter D.; Suk, Thomas J.

    1986-01-01

    A water-sampling apparatus used for the isolation and detection of Giardia cysts in water has been designed and tested. The sampling apparatus uses one of a variety of pumps or waterline pressure to move water through a filter. Two of the optional pumps are lightweight enough to make the apparatus portable and thus suitable for sampling in remote areas. This technique of sample processing produces good cyst recovery in much less time than is required with previously established methods. Giardia cysts are identified using direct immunofluorescence.

  10. Power ratio estimation in incoherent backscatter lidar: direct detection with Gaussian noise.

    PubMed

    Rye, B J

    1989-09-01

    Properties of small sample estimators for the return signal power ratio or log ratio in direct detection incoherent backscatter lidar systems are analyzed. As for heterodyne receivers it is usually preferable to form an estimator from the logarithmic difference of the sample averages rather than their ratio. Calculated values of bias and noise figures are confirmed using simulated data based on constant signal models and compared with the estimates obtained from nonlinear Kalman filters. The latter generally provide the least bias at high noise levels at the cost of greater computational complexity.

  11. Terahertz Direct Detection Characteristics of a Superconducting NbN Bolometer

    NASA Astrophysics Data System (ADS)

    Ren, Yuan; Miao, Wei; Yao, Qi-Jun; Zhang, Wen; Shi, Sheng-Cai

    2011-01-01

    We report the terahertz direct detection characteristics of a spiral antenna coupled NbN superconducting hot-electron bolometer (HEB) at a bath temperature of 4.2 K. Thermal conductance determined from resistance transition curves with different bias currents is found to be 3 × 10-7 W/K. The device shows a read-out circuit limited noise equivalent power (NEP) of 4.5 × 10-12 W/Hz1/2 at 4.2 K with a home-made transimpedance amplifier operating at room temperature.

  12. Wavelet packet transform-based optical orthogonal frequency-division multiplexing transmission using direct detection

    NASA Astrophysics Data System (ADS)

    Zhang, Hongbo; Yi, Xingwen; Chen, Lei; Zhang, Jing; Deng, Mingliang; Qiu, Kun

    2012-10-01

    As an alternate to fast Fourier transform-based orthogonal frequency-division multiplexing (OFDM), wavelet packet transform (WPT)-based OFDM (WPT-OFDM) does not require cyclic prefix to avoid inter-symbol-interference. The wavelet has many varieties and therefore, it can provide more freedom for system design to suit different applications. We propose a real-valued WPT-OFDM that uses intensity modulation/direct detection. We also conduct an experiment to verify its performance through a 75-km standard single-mode fiber.

  13. Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter

    NASA Astrophysics Data System (ADS)

    Sorensen, Peter; Dahl, Carl Eric

    2011-03-01

    We show for the first time that the quenching of electronic excitation from nuclear recoils in liquid xenon is well-described by Lindhard theory, if the nuclear recoil energy is reconstructed using the combined (scintillation and ionization) energy scale proposed by Shutt et al. We argue for the adoption of this perspective in favor of the existing preference for reconstructing nuclear recoil energy solely from primary scintillation. We show that signal partitioning into scintillation and ionization is well described by the Thomas-Imel box model. We discuss the implications for liquid xenon detectors aimed at the direct detection of dark matter.

  14. Direct-detection mode-division multiplexing in modal basis using phase retrieval.

    PubMed

    Arik, Sercan Ö; Kahn, Joseph M

    2016-09-15

    Mode-division multiplexing (MDM) can increase the capacity of direct-detection short-reach systems in proportion to the number of modes employed. MDM requires compensation of modal crosstalk at a transmitter or receiver by the multi-input multi-output (MIMO) signal processing. We show that the channel estimation required for the MIMO processing in a basis of modes can be expressed as a phase retrieval problem. We propose three techniques for the estimation: sparse training sequences, convex optimization (CO) and alternating minimization. We demonstrate the superior performance of the CO technique. PMID:27628373

  15. Low-background underground facilities for the direct detection of dark matter

    SciTech Connect

    Barnes, P.D. Jr. |; Caldwell, D.; DaSilva, A.

    1992-12-31

    This is the report of a working group formed to discuss the requirements of an underground facility for experiments trying to detect directly dark matter particles. There is a brief discussion of the general properties of underground facilities, focusing on the levels of muon induced backgrounds that are tolerable. Then the authors review the scientific motivation of the search for dark matter particles, and the existing experimental limits. There is a short description of the shielding necessary to reach the desired background levels. Finally, they report the results of their preliminary study of muon induced backgrounds in dark matter experiments, and the implications for the required depth of the facilities for such experiments.

  16. Wind Profiles Obtained with a Molecular Direct Detection Doppler Lidar During IHOP-2002

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Chen, Huai-Lin; Li, Steven X.; Mathur, Savyasachee; Dobler, Jeremy; Hasselbrack, William; Comer, Joseph

    2004-01-01

    The Goddard Lidar Observatory for Winds (GLOW) is a mobile direct detection Doppler lidar system which uses the double edge technique to measure the Doppler shift of the molecular backscattered laser signal at a wavelength of 355 nm. In the spring of 2002 GLOW was deployed to the western Oklahoma profiling site (36 deg 33.500 min. N, 100 deg. 36.371 min. W) to participate in the International H2O Project (IHOP). During the IHOP campaign over 240 hours of wind profiles were obtained with the GLOW lidar in support of a variety of scientific investigations.

  17. Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter

    SciTech Connect

    Sorensen, P; Dahl, C E

    2011-02-14

    We show for the first time that the quenching of electronic excitation from nuclear recoils in liquid xenon is well-described by Lindhard theory, if the nuclear recoil energy is reconstructed using the combined (scintillation and ionization) energy scale proposed by Shutt et al.. We argue for the adoption of this perspective in favor of the existing preference for reconstructing nuclear recoil energy solely from primary scintillation. We show that signal partitioning into scintillation and ionization is well-described by the Thomas-Imel box model. We discuss the implications for liquid xenon detectors aimed at the direct detection of dark matter.

  18. Precise Detection of Direct Glomerular Input Duration by the Olfactory Bulb

    PubMed Central

    Li, Anan; Gire, David H.; Bozza, Thomas

    2014-01-01

    Sensory neuron input to the olfactory bulb (OB) was activated precisely for different durations with blue light in mice expressing channelrhodopsin-2 in olfactory sensory neurons. Behaviorally the mice discriminated differences of 10 ms in duration of direct glomerular activation. In addition, a subset of mitral/tufted cells in the OB of awake mice responded tonically therefore conveying information on stimulus duration. Our study provides evidence that duration of the input to glomeruli not synchronized to sniffing is detected. This potent cue may be used to obtain information on puffs in odor plumes. PMID:25429146

  19. Prospects for direct detection of dark matter in an effective theory approach

    SciTech Connect

    Catena, Riccardo

    2014-07-01

    We perform the first comprehensive analysis of the prospects for direct detection of dark matter with future ton-scale detectors in the general 11-dimensional effective theory of isoscalar dark matter-nucleon interactions mediated by a heavy spin-1 or spin-0 particle. The theory includes 8 momentum and velocity dependent dark matter-nucleon interaction operators, besides the familiar spin-independent and spin-dependent operators. From a variegated sample of 27 benchmark points selected in the parameter space of the theory, we simulate independent sets of synthetic data for ton-scale Germanium and Xenon detectors. From the synthetic data, we then extract the marginal posterior probability density functions and the profile likelihoods of the model parameters. The associated Bayesian credible regions and frequentist confidence intervals allow us to assess the prospects for direct detection of dark matter at the 27 benchmark points. First, we analyze the data assuming the knowledge of the correct dark matter nucleon-interaction type, as it is commonly done for the familiar spin-independent and spin-dependent interactions. Then, we analyze the simulations extracting the dark matter-nucleon interaction type from the data directly, in contrast to standard analyses. This second approach requires an extensive exploration of the full 11-dimensional parameter space of the dark matter-nucleon effective theory. Interestingly, we identify 5 scenarios where the dark matter mass and the dark matter-nucleon interaction type can be reconstructed from the data simultaneously. We stress the importance of extracting the dark matter nucleon-interaction type from the data directly, discussing the main challenges found addressing this complex 11-dimensional problem.

  20. Assessing alternatives for directional detection of a halo of weakly interacting massive particles

    SciTech Connect

    Copi, Craig J.; Krauss, Lawrence M.; Simmons-Duffin, David; Stroiney, Steven R.

    2007-01-15

    The future of direct terrestrial WIMP detection lies on two fronts: new, much larger low background detectors sensitive to energy deposition, and detectors with directional sensitivity. The former can explore a large range of WIMP parameter space using well-tested technology while the latter may be necessary if one is to disentangle particle physics parameters from astrophysical halo parameters. Because directional detectors will be quite difficult to construct it is worthwhile exploring in advance generally which experimental features will yield the greatest benefits at the lowest costs. We examine the sensitivity of directional detectors with varying angular tracking resolution with and without the ability to distinguish forward versus backward recoils, and compare these to the sensitivity of a detector where the track is projected onto a two-dimensional plane. The latter detector regardless of where it is placed on the Earth, can be oriented to produce a significantly better discrimination signal than a 3D detector without this capability, and with sensitivity within a factor of 2 of a full 3D tracking detector. Required event rates to distinguish signals from backgrounds for a simple isothermal halo range from the low teens in the best case to many thousands in the worst.

  1. Challenges of Detecting Directional Selection After a Bottleneck: Lessons From Sorghum bicolor

    PubMed Central

    Hamblin, Martha T.; Casa, Alexandra M.; Sun, Hong; Murray, Seth C.; Paterson, Andrew H.; Aquadro, Charles F.; Kresovich, Stephen

    2006-01-01

    Multilocus surveys of sequence variation can be used to identify targets of directional selection, which are expected to have reduced levels of variation. Following a population bottleneck, the signal of directional selection may be hard to detect because many loci may have low variation by chance and the frequency spectrum of variation may be perturbed in ways that resemble the effects of selection. Cultivated Sorghum bicolor contains a subset of the genetic diversity found in its wild ancestor(s) due to the combined effects of a domestication bottleneck and human selection on traits associated with agriculture. As a framework for distinguishing between the effects of demography and selection, we sequenced 204 loci in a diverse panel of 17 cultivated S. bicolor accessions. Genomewide patterns of diversity depart strongly from equilibrium expectations with regard to the variance of the number of segregating sites, the site frequency spectrum, and haplotype configuration. Furthermore, gene genealogies of most loci with an excess of low frequency variants and/or an excess of segregating sites do not show the characteristic signatures of directional and diversifying selection, respectively. A simple bottleneck model provides an improved but inadequate fit to the data, suggesting the action of other population-level factors, such as population structure and migration. Despite a known history of recent selection, we find little evidence for directional selection, likely due to low statistical power and lack of an appropriate null model. PMID:16547110

  2. Assessing alternatives for directional detection of a halo of weakly interacting massive particles

    NASA Astrophysics Data System (ADS)

    Copi, Craig J.; Krauss, Lawrence M.; Simmons-Duffin, David; Stroiney, Steven R.

    2007-01-01

    The future of direct terrestrial WIMP detection lies on two fronts: new, much larger low background detectors sensitive to energy deposition, and detectors with directional sensitivity. The former can explore a large range of WIMP parameter space using well-tested technology while the latter may be necessary if one is to disentangle particle physics parameters from astrophysical halo parameters. Because directional detectors will be quite difficult to construct it is worthwhile exploring in advance generally which experimental features will yield the greatest benefits at the lowest costs. We examine the sensitivity of directional detectors with varying angular tracking resolution with and without the ability to distinguish forward versus backward recoils, and compare these to the sensitivity of a detector where the track is projected onto a two-dimensional plane. The latter detector regardless of where it is placed on the Earth, can be oriented to produce a significantly better discrimination signal than a 3D detector without this capability, and with sensitivity within a factor of 2 of a full 3D tracking detector. Required event rates to distinguish signals from backgrounds for a simple isothermal halo range from the low teens in the best case to many thousands in the worst.

  3. Direct, Specific and Rapid Detection of Staphylococcal Proteins and Exotoxins Using a Multiplex Antibody Microarray

    PubMed Central

    Stieber, Bettina; Monecke, Stefan; Müller, Elke; Büchler, Joseph; Ehricht, Ralf

    2015-01-01

    Background S. aureus is a pathogen in humans and animals that harbors a wide variety of virulence factors and resistance genes. This bacterium can cause a wide range of mild to life-threatening diseases. In the latter case, fast diagnostic procedures are important. In routine diagnostic laboratories, several genotypic and phenotypic methods are available to identify S. aureus strains and determine their resistances. However, there is a demand for multiplex routine diagnostic tests to directly detect staphylococcal toxins and proteins. Methods In this study, an antibody microarray based assay was established and validated for the rapid detection of staphylococcal markers and exotoxins. The following targets were included: staphylococcal protein A, penicillin binding protein 2a, alpha- and beta-hemolysins, Panton Valentine leukocidin, toxic shock syndrome toxin, enterotoxins A and B as well as staphylokinase. All were detected simultaneously within a single experiment, starting from a clonal culture on standard media. The detection of bound proteins was performed using a new fluorescence reading device for microarrays. Results 110 reference strains and clinical isolates were analyzed using this assay, with a DNA microarray for genotypic characterization performed in parallel. The results showed a general high concordance of genotypic and phenotypic data. However, genotypic analysis found the hla gene present in all S. aureus isolates but its expression under given conditions depended on the clonal complex affiliation of the actual isolate. Conclusions The multiplex antibody assay described herein allowed a rapid and reliable detection of clinically relevant staphylococcal toxins as well as resistance- and species-specific markers. PMID:26624622

  4. Direct detection of N-H[...]O=C hydrogen bonds in biomolecules by NMR spectroscopy.

    PubMed

    Cordier, Florence; Nisius, Lydia; Dingley, Andrew J; Grzesiek, Stephan

    2008-01-01

    A nuclear magnetic resonance (NMR) experiment is described for the direct detection of N-H[...]O=C hydrogen bonds (H-bonds) in 15N and 13C isotope-labeled biomolecules. This quantitative 'long-range' HNCO-COSY (correlation spectroscopy) experiment detects and quantifies electron-mediated scalar couplings across the H-bond (H-bond scalar couplings), which connect the magnetically active (15)N and (13)C nuclei on both sides of the H-bond. Detectable H-bonds comprise the canonical backbone H-bonds in proteins as well as other H-bonds in proteins and nucleic acids with N-H donors and O=C (carbonylic or carboxylic) acceptors. Unlike other NMR observables, which provide only indirect evidence of the presence of H-bonds, the H-bond scalar couplings identify all partners of the H-bond, the donor, the donor proton and the acceptor, in a single experiment. The size of the scalar couplings can be related to H-bond geometries. The time required to detect the N-H[...]O=C H-bonds in small proteins (< or = approximately 10 kDa) is typically on the order of 1 d at millimolar concentrations, whereas H-bond detection for larger proteins (< or = approximately 30 kDa) may be possible within several days depending on concentration, isotope composition, magnetic field strength and molecular weight. The proteins ubiquitin (8.6 kDa), dimeric RANTES (2 x 8.5 kDa) and MAP30 (30 kDa) are used as examples to illustrate this procedure. PMID:18274525

  5. Status of Experiments for Direct Detection of Galactic Dark Matter Particles

    NASA Astrophysics Data System (ADS)

    Smith, Peter

    Three general categories of particle have been considered as candidates for Galactic Dark Matter - neutrinos, axions and weakly interacting massive particles (WIMPS). The main experimental principles available for detecting these will be outlined. The majority of world effort is currently concentrated on sensitive WIMP searches, motivated in particular by supersymmetry theory, which predicts a stable neutral particle in the mass range 10-1000 GeV and which would have clustered in Galaxies in association with baryonic matter. These would produce low energy nuclear recoils, which are being sought by underground low background scintillator and cryogenic techniques capable of distinguishing these from background events. World progress towards bringing these techniques to the required sensitivity is summarised, together with current experimental limits. Further developments include detectors with directional sensitivity, allowing correlation of any signals with the earth-WIMP relative motion. The first of these forms part of the expanded dark matter programme at the UK Boulby Mine facility. Relic neutrinos could also form a component of the dark matter if any has a cosologically significant mass, and a new detector is proposed to determine this from a Galactic supernova burst. More distant future possibilities for direct detection of relic neutrinos will be outlined.

  6. Quantifying (dis)agreement between direct detection experiments in a halo-independent way

    SciTech Connect

    Feldstein, Brian; Kahlhoefer, Felix E-mail: felix.kahlhoefer@physics.ox.ac.uk

    2014-12-01

    We propose an improved method to study recent and near-future dark matter direct detection experiments with small numbers of observed events. Our method determines in a quantitative and halo-independent way whether the experiments point towards a consistent dark matter signal and identifies the best-fit dark matter parameters. To achieve true halo independence, we apply a recently developed method based on finding the velocity distribution that best describes a given set of data. For a quantitative global analysis we construct a likelihood function suitable for small numbers of events, which allows us to determine the best-fit particle physics properties of dark matter considering all experiments simultaneously. Based on this likelihood function we propose a new test statistic that quantifies how well the proposed model fits the data and how large the tension between different direct detection experiments is. We perform Monte Carlo simulations in order to determine the probability distribution function of this test statistic and to calculate the p-value for both the dark matter hypothesis and the background-only hypothesis.

  7. Direct competitive chemiluminescence immunoassays based on gold-coated magnetic particles for detection of chloramphenicol.

    PubMed

    Liang, Xiaohui; Fang, Xiangyi; Yao, Manwen; Yang, Yucong; Li, Junfeng; Liu, Hongjun; Wang, Linyu

    2016-02-01

    Direct competitive chemiluminescence immunoassays (CLIA) based on gold-coated magnetic nanospheres (Au-MNPs) were developed for rapid analysis of chloramphenicol (CAP). The Au-MNPs were modified with carboxyl groups and amino groups by 11-mercaptoundecanoic acid (MUA) and cysteamine respectively, and then were respectively conjugated with CAP base and CAP succinate via an activating reaction using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). NSP-DMAE-NHS, a new and effective luminescence reagent, was employed to label anti-CAP antibody (mAb) as a tracer in direct CLIA for CAP detection using a 'homemade' luminescent measurement system that was set up with a photomultiplier tube (PMT) and a photon counting unit linked to a computer. The sensitivities and limits of detection (LODs) of the two methods were obtained and compared according to the inhibition curves. The 50% inhibition concentration (IC50 ) values of the two methods were about 0.044 ng/mL and 0.072 ng/mL respectively and LODs were approximately 0.001 ng/mL and 0.006 ng/mL respectively. To our knowledge, they were much more sensitive than any traditional enzyme-linked immunosorbent assay (ELISA) ever reported. Moreover, the new luminescence reagent NSP-DMAE-NHS is much more sensitive and stable than luminol and its derivatives, contributing to the sensitivity enhancement.

  8. First direct detection limits on sub-GeV dark matter from XENON10.

    PubMed

    Essig, Rouven; Manalaysay, Aaron; Mardon, Jeremy; Sorensen, Peter; Volansky, Tomer

    2012-07-13

    The first direct detection limits on dark matter in the MeV to GeV mass range are presented, using XENON10 data. Such light dark matter can scatter with electrons, causing ionization of atoms in a detector target material and leading to single- or few-electron events. We use 15  kg day of data acquired in 2006 to set limits on the dark-matter-electron scattering cross section. The strongest bound is obtained at 100 MeV where σ(e)<3×10(-38)  cm2 at 90% C.L., while dark-matter masses between 20 MeV and 1 GeV are bounded by σ(e)<10(-37)  cm2 at 90% C.L. This analysis provides a first proof of principle that direct detection experiments can be sensitive to dark-matter candidates with masses well below the GeV scale.

  9. Direct measurement of singlet oxygen by using a photomultiplier tube-based detection system.

    PubMed

    Kim, In-Wook; Park, Jae Myung; Roh, Yoon Jin; Kim, Ju Hee; Choi, Myung-Gyu; Hasan, Tayyaba

    2016-06-01

    The effective dosimetry for photodynamic therapy (PDT) can be specified by direct measurement of singlet oxygen ((1)O2) production. The purpose of this study was to investigate the feasibility of a newly developed photomultiplier tube (PMT)-based singlet oxygen detection (SOD) system. The lowest and highest (1)O2 concentrations detectable by the PMT-SOD system were 15nM and 10μM, respectively. Dose-dependent quenching, by NaN3, of the fluorogenic reaction was observed, which was negatively correlated with the (1)O2 level measured by the PMT-SOD system. The lifetime of (1)O2, as measured by the PMT-SOD system, was found to be lengthened when H2O was replaced with deuterium oxide. (1)O2 photon counts were significantly and dose-dependently correlated with intracellular fluorescence intensity after photosensitizer treatments. In vitro cell viability test and in vivo xenografted-tumor mass shrinkage showed a positive association between PDT-induced cytotoxicity and (1)O2 production concomitantly measured by the PMT-SOD system. It was concluded that the PMT-SOD system is capable of measuring (1)O2 production directly and accurately, demonstrating that this system can be useful in the determination of dosimetry for PDT. PMID:26995671

  10. Direct competitive chemiluminescence immunoassays based on gold-coated magnetic particles for detection of chloramphenicol.

    PubMed

    Liang, Xiaohui; Fang, Xiangyi; Yao, Manwen; Yang, Yucong; Li, Junfeng; Liu, Hongjun; Wang, Linyu

    2016-02-01

    Direct competitive chemiluminescence immunoassays (CLIA) based on gold-coated magnetic nanospheres (Au-MNPs) were developed for rapid analysis of chloramphenicol (CAP). The Au-MNPs were modified with carboxyl groups and amino groups by 11-mercaptoundecanoic acid (MUA) and cysteamine respectively, and then were respectively conjugated with CAP base and CAP succinate via an activating reaction using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). NSP-DMAE-NHS, a new and effective luminescence reagent, was employed to label anti-CAP antibody (mAb) as a tracer in direct CLIA for CAP detection using a 'homemade' luminescent measurement system that was set up with a photomultiplier tube (PMT) and a photon counting unit linked to a computer. The sensitivities and limits of detection (LODs) of the two methods were obtained and compared according to the inhibition curves. The 50% inhibition concentration (IC50 ) values of the two methods were about 0.044 ng/mL and 0.072 ng/mL respectively and LODs were approximately 0.001 ng/mL and 0.006 ng/mL respectively. To our knowledge, they were much more sensitive than any traditional enzyme-linked immunosorbent assay (ELISA) ever reported. Moreover, the new luminescence reagent NSP-DMAE-NHS is much more sensitive and stable than luminol and its derivatives, contributing to the sensitivity enhancement. PMID:26031849

  11. Direct detection of chloramphenicol in honey by neutral desorption-extractive electrospray ionization mass spectrometry.

    PubMed

    Huang, X Y; Fang, X W; Zhang, X; Dai, X M; Guo, X L; Chen, H W; Luo, L P

    2014-11-01

    Herein, we constructed a platform of neutral desorption-extractive electrospray ionization mass spectrometry (ND-EESI-MS) for direct and rapid detection of chloramphenicol (CAP) in honey samples diluted with methanol. Under the optimized working conditions, the quantitative information of CAP residues was acquired effectively by EESI-Ion Trap MS (n) . Using heated methanol-N2 as spray reagent, we reduced the limit of determination (LOD) from 73.3 ng/mL to 0.3 ng/mL, and the CAP detection is linear in the range of 1-5000 ng/mL (R = 0.9947). For the honey samples with CAP of 10, 100, and 1000 ng/mL, the recoveries were 133.0, 80.6, and 101.1%, and the relative standard deviations were 5.96, 8.82, and 8.71%, respectively. The reproducibility assays showed the stability of this method. Therefore, this ND-EESI-MS method is powerful for direct, rapid, and quantitative CAP analysis in honey samples with high sensitivity, precision, and specificity. PMID:25277102

  12. Patterned electrode-based amperometric gas sensor for direct nitric oxide detection within microfluidic devices.

    PubMed

    Cha, Wansik; Tung, Yi-Chung; Meyerhoff, Mark E; Takayama, Shuichi

    2010-04-15

    This article describes a thin amperometric nitric oxide (NO) sensor that can be microchannel embedded to enable direct real-time detection of NO produced by cells cultured within the microdevice. A key for achieving the thin ( approximately 1 mm) planar sensor configuration required for sensor-channel integration is the use of gold/indium-tin oxide patterned electrode directly on a porous polymer membrane (pAu/ITO) as the base working electrode. The electrochemically deposited Au-hexacyanoferrate layer on pAu/ITO is used to catalyze NO oxidation to nitrite at lower applied potentials (0.65-0.75 V vs Ag/AgCl) and stabilize current output. Furthermore, use of a gas-permeable membrane to separate internal sensor compartments from the sample phase imparts excellent NO selectivity over common interfering agents (e.g., nitrite, ascorbate, ammonia, etc.) present in culture media and biological fluids. The optimized sensor design reversibly detects NO down to the approximately 1 nM level in stirred buffer and <10 nM in flowing buffer when integrated within a polymeric microfluidic device. We demonstrate utility of the channel-embedded sensor by monitoring NO generation from macrophages cultured within non-gas-permeable microchannels, as they are stimulated with endotoxin. PMID:20329749

  13. Form factor effects in the direct detection of isospin-violating dark matter

    SciTech Connect

    Zheng, Hao; Zhang, Zhen; Chen, Lie-Wen E-mail: malkuth@sjtu.edu.cn

    2014-08-01

    Isospin-violating dark matter (IVDM) provides a possible mechanism to ameliorate the tension among recent direct detection experiments. For IVDM, we demonstrate that the results of direct detection experiments based on neutron-rich target nuclei may depend strongly on the density dependence of the symmetry energy which is presently largely unknown and controls the neutron skin thickness that reflects the relative difference of neutron and proton form factors in the neutron-rich nuclei. In particular, using the neutron and proton form factors obtained from Skyrme-Hartree-Fock calculations by varying the symmetry energy within the uncertainty region set by the latest model-independent measurement of the neutron skin thickness of {sup 208}Pb from PREX experiment at JLab, we find that, for IVDM with neutron-to-proton coupling ratio fixed to f{sub n}/f{sub p}=-0.7, the form factor effect may enhance the sensitivity of Xe-based detectors (e.g., XENON100 and LUX) to the DM-proton cross section by a factor of 3 in the DM mass region constrained by CMDS-II(Si) and even by more than an order of magnitude for heavy DM with mass larger than 80 GeV, compared with the results using the empirical Helm form factor. Our results further indicate that the form factor effect can significantly modify the recoil spectrum of Xe-based detectors for heavy IVDM with f{sub n}/f{sub p}=-0.7.

  14. Turbine Reliability and Operability Optimization through the use of Direct Detection Lidar Final Technical Report

    SciTech Connect

    Johnson, David K; Lewis, Matthew J; Pavlich, Jane C; Wright, Alan D; Johnson, Kathryn E; Pace, Andrew M

    2013-02-01

    The goal of this Department of Energy (DOE) project is to increase wind turbine efficiency and reliability with the use of a Light Detection and Ranging (LIDAR) system. The LIDAR provides wind speed and direction data that can be used to help mitigate the fatigue stress on the turbine blades and internal components caused by wind gusts, sub-optimal pointing and reactionary speed or RPM changes. This effort will have a significant impact on the operation and maintenance costs of turbines across the industry. During the course of the project, Michigan Aerospace Corporation (MAC) modified and tested a prototype direct detection wind LIDAR instrument; the resulting LIDAR design considered all aspects of wind turbine LIDAR operation from mounting, assembly, and environmental operating conditions to laser safety. Additionally, in co-operation with our partners, the National Renewable Energy Lab and the Colorado School of Mines, progress was made in LIDAR performance modeling as well as LIDAR feed forward control system modeling and simulation. The results of this investigation showed that using LIDAR measurements to change between baseline and extreme event controllers in a switching architecture can reduce damage equivalent loads on blades and tower, and produce higher mean power output due to fewer overspeed events. This DOE project has led to continued venture capital investment and engagement with leading turbine OEMs, wind farm developers, and wind farm owner/operators.

  15. THE TRENDS HIGH-CONTRAST IMAGING SURVEY. II. DIRECT DETECTION OF THE HD 8375 TERTIARY

    SciTech Connect

    Crepp, Justin R.; Johnson, John Asher; Yantek, Scott M.; Howard, Andrew W.; Marcy, Geoff W.; Isaacson, Howard; Fischer, Debra A.; Wright, Jason T.; Feng Ying

    2013-07-01

    We present the direct imaging detection of a faint tertiary companion to the single-lined spectroscopic binary HD 8375 AB. Initially noticed as an 53 m s{sup -1} yr{sup -1} Doppler acceleration by Bowler et al., we have obtained high-contrast adaptive optics observations at Keck using NIRC2 that spatially resolve HD 8375 C from its host(s). Astrometric measurements demonstrate that the companion shares a common proper-motion. We detect orbital motion in a clockwise direction. Multiband relative photometry measurements are consistent with an early M-dwarf spectral type ({approx}M1V). Our combined Doppler and imaging observations place a lower-limit of m {>=} 0.297 M{sub Sun} on its dynamical mass. We also provide a refined orbit for the inner pair using recent radial velocity measurements obtained with the High Resolution Echelle Spectrometer. HD 8375 is one of many triple-star systems that are apparently missing in the solar neighborhood.

  16. Directional surface plasmon-coupled emission: a new method for high sensitivity detection

    PubMed Central

    Lakowicz, Joseph R.; Malicka, Joanna; Gryczynski, Ignacy; Gryczynski, Zygmunt

    2009-01-01

    Fluorescence emission is nearly isotropic in space. With typical optical components the collection efficiency is 1% or less. In this preliminary report, we describe a novel approach to transforming the normally isotropic emission into directional emission with a collection efficiency near 50%. This can be accomplished for fluorophores located near a semi-transparent silver film on a glass substrate. The emission couples with the surface plasmon resonance on the silver surface and enters the transparent substrate at a sharply defined angle, the surface plasmon angle for the emission wavelength. We estimate that 40–70% of the total emission enters the substrate at the plasmon angle and can thus be directed towards a detector. Background emission from fluorophores distant from the silver does not couple with the plasmon and is not detected. Different emission wavelengths couple at different angles allowing spectral discrimination without additional optics. Surface plasmon-coupled emission represents a new technology which can be used for high detection efficiency with microfluidic and/or surface-bound assay formats. PMID:12893239

  17. Form factor effects in the direct detection of isospin-violating dark matter

    NASA Astrophysics Data System (ADS)

    Zheng, Hao; Zhang, Zhen; Chen, Lie-Wen

    2014-08-01

    Isospin-violating dark matter (IVDM) provides a possible mechanism to ameliorate the tension among recent direct detection experiments. For IVDM, we demonstrate that the results of direct detection experiments based on neutron-rich target nuclei may depend strongly on the density dependence of the symmetry energy which is presently largely unknown and controls the neutron skin thickness that reflects the relative difference of neutron and proton form factors in the neutron-rich nuclei. In particular, using the neutron and proton form factors obtained from Skyrme-Hartree-Fock calculations by varying the symmetry energy within the uncertainty region set by the latest model-independent measurement of the neutron skin thickness of 208Pb from PREX experiment at JLab, we find that, for IVDM with neutron-to-proton coupling ratio fixed to fn/fp=-0.7, the form factor effect may enhance the sensitivity of Xe-based detectors (e.g., XENON100 and LUX) to the DM-proton cross section by a factor of 3 in the DM mass region constrained by CMDS-II(Si) and even by more than an order of magnitude for heavy DM with mass larger than 80 GeV, compared with the results using the empirical Helm form factor. Our results further indicate that the form factor effect can significantly modify the recoil spectrum of Xe-based detectors for heavy IVDM with fn/fp=-0.7.

  18. Calibration of Liquid Xenon Time Projection Chambers for the Direct Detection of Dark Matter

    NASA Astrophysics Data System (ADS)

    Kastens, Louis William, IV

    Contemporary cosmological observations strongly suggest the presence of weakly interacting massive particles (WIMPs) which have not been directly detected to date. In this paper, I discuss the cosmological evidence which suggests the presence of WIMPs, and the justification for believing the cosmological models built around this evidence are sound. I will then discuss the expected WIMP-nucleon interaction rate, and methods of directly detecting these interactions, emphasizing liquid xenon two phase time projection chambers. Two of these liquid xenon time projection chambers will be discussed in detail, from design philosophies, construction, operation, and results to date. Finally, a novel method of calibrating large liquid xenon detectors with 83 mKr will be discussed. Calibration with a 83 mKr source allows for low energy electronic recoils in the fiducial region of the detector, a calibration need which traditional external sources cannot meet. The development of the 83 mKr source for use in a low-background dark matter detector is discussed.

  19. Stratum corneum antibodies detected by hemagglutination are not directed against keratin intermediate filaments.

    PubMed

    Qutaishat, S; Kumar, V; Beutner, E H; Jabłońska, S

    1990-01-01

    Autoantibodies to stratum corneum (SC) occur in virtually all normal adult human sera. These antibodies may be directed against various antigens of the SC. They have been detected by indirect immunofluorescence, passive hemagglutination (HA), immune adherence, and most recently by enzyme immunoassay and immunoblot methods. The purpose of our study was to examine whether antibodies to SC antigens as detected by passive HA are similar to the keratin intermediate filament (KIF) reactive antibodies. SC antigen preparation was prepared from psoriatic scales by the trypsin-phenol-water (TPW) extraction method. KIFs were prepared by 8 M urea extraction of normal callus or psoriatic scales. The anti-SC antibody titers of normal human sera were determined by passive HA before and after absorption with TPW-SC antigen preparation and upon absorption with KIFs. Similarly, titers of anti-KIF antibodies were determined on absorbed and unabsorbed sera by immunoblot assay. The results of this study indicate that the absorption of the sera with KIFs did not affect the titer of antibodies to TPW-extractable SC antigens whereas the titer of KIF antibodies dropped. KIF-reactive antibodies, on the other hand, were not affected by absorption with TPW-SC antigen, whereas the latter absorbed out the corresponding reactive antibodies. These results indicate that antibodies directed against SC antigen are different from the KIF-reactive antibodies.

  20. Direct MRI detection of the neuronal magnetic field: the effect of the dendrite branch.

    PubMed

    Huang, Ying-Ling; Xiong, Hong-Chuan; Yao, De-Zhong

    2010-09-21

    In recent years, neuronal current MRI (nc-MRI) was proposed as a new imaging method to directly map the magnetic field change caused by neuronal activity. Nc-MRI could offer improved spatial and temporal resolution compared to blood hemodynamics-based functional magnetic resonance imaging (fMRI). In this paper, with a finite current dipole as the model of dendrite or dendrite branch, we investigated the spatial distribution of the magnetic field generated by synchronously activated neurons to evaluate the possibility of nc-MRI. Our simulations imply that the existence of a dendrite branch may not only increase the strength of the neuronal magnetic field (NMF), but also raise the non-uniform and unsymmetry of the NMF; therefore, it can enhance the detectability of the neuronal current magnetic field by MRI directly. The results show that the signal phase shift is enlarged, but it is unstable and is still very small, <1 radian, while the magnitude signal may be strong enough for a typical MRI voxel to be detected. We suggest making further efforts to measure the magnitude signal which may induce a large effect in an nc-MRI experiment.

  1. DNA-Directed Antibody Immobilization for Enhanced Detection of Single Viral Pathogens.

    PubMed

    Seymour, Elif; Daaboul, George G; Zhang, Xirui; Scherr, Steven M; Ünlü, Nese Lortlar; Connor, John H; Ünlü, M Selim

    2015-10-20

    Here, we describe the use of DNA-conjugated antibodies for rapid and sensitive detection of whole viruses using a single-particle interferometric reflectance imaging sensor (SP-IRIS), a simple, label-free biosensor capable of imaging individual nanoparticles. First, we characterize the elevation of the antibodies conjugated to a DNA sequence on a three-dimensional (3-D) polymeric surface using a fluorescence axial localization technique, spectral self-interference fluorescence microscopy (SSFM). Our results indicate that using DNA linkers results in significant elevation of the antibodies on the 3-D polymeric surface. We subsequently show the specific detection of pseudotyped vesicular stomatitis virus (VSV) as a model virus on SP-IRIS platform. We demonstrate that DNA-conjugated antibodies improve the capture efficiency by achieving the maximal virus capture for an antibody density as low as 0.72 ng/mm(2), whereas for unmodified antibody, the optimal virus capture requires six times greater antibody density on the sensor surface. We also show that using DNA conjugated anti-EBOV GP (Ebola virus glycoprotein) improves the sensitivity of EBOV-GP carrying VSV detection compared to directly immobilized antibodies. Furthermore, utilizing a DNA surface for conversion to an antibody array offers an easier manufacturing process by replacing the antibody printing step with DNA printing. The DNA-directed immobilization technique also has the added advantages of programmable sensor surface generation based on the need and resistance to high temperatures required for microfluidic device fabrication. These capabilities improve the existing SP-IRIS technology, resulting in a more robust and versatile platform, ideal for point-of-care diagnostics applications. PMID:26378807

  2. Using a CCD for the direct detection of electrons in a low energy space plasma spectrometer

    NASA Astrophysics Data System (ADS)

    Bedington, R.; Kataria, D.; Walton, D.

    2012-01-01

    An E2V CCD64 back-illuminated, ion-implanted CCD (charge-coupled device) has been used as a direct electron imaging detector with CATS (Conceptual And Tiny Spectrometer), a highly miniaturised prototype plasma analyser head. This is in place of an MCP (microchannel plate) with a position sensing anode which would more conventionally be used as a detector in traditional low energy space plasma analyser instruments. The small size of CATS however makes it well matched to the size of the CCD, and the ion implants reduce the depth of the CCD backside electron potential well making it more sensitive to lower energy electrons than standard untreated silicon. Despite ionisation damage from prolonged exposure to excessively energetic electrons, the CCD has been able to detect electrons with energies above 500eV, at temperatures around room temperature. Using both a long integration 'current measuring' mode and a short integration `electron counting' mode it has been used to image the low energy electrons exiting the analyser, enhancing our understanding of the CATS electrostatic optics. The CCD has been selected as the detector for use with CATS for an instrument on a low-altitude student sounding rocket flight. Although it cannot detect the lowest energy electrons that an MCP can detect, and it is more sensitive to stray light, the low voltages required, the lack of vacuum requirements and its novelty and availability made it the most attractive candidate detector.

  3. A new electrochemically active-inactive switching aptamer molecular beacon to detect thrombin directly in solution.

    PubMed

    Cheng, Guifang; Shen, Bijun; Zhang, Fan; Wu, Jikui; Xu, Ying; He, Pingang; Fang, Yuzhi

    2010-06-15

    A new electrochemical aptamer molecular beacon (MB) was designed by the carminic acid (CA) covalently linking at the each end of a special single-stranded stem-loop shaped oligonucleotide and named as CAs-MB. CA is an electrochemically active molecule and two CA molecules at the ends of molecular beacon stem were closed enough to associate each other to be as CA dimer. The dimer was electrochemically inactive. It separated into two CA monomers and produced the electrochemical signal while CAs-MB combined with target. In this protocol, the detection strategy of CAs-MB for thrombin is based on electrochemical active-inactive switching between monomer and dimer forms of CA. In order to enhance the electrochemical signal, magnetic nanobeads (MNB) was applied by connecting CAs-MB with MNB through a duplex of DNA. With the magnetic enrichment, the detection limit for thrombin reached to 42.4 pM. The experiment results showed that this type of electrochemical active-inactive switching aptamer molecular beacon allowed the direct detection of target proteins in the solution with no requirement of removing uncombined CAs-MB. Besides, CAs-MB/MNB can be easily regenerated by using 2M NaCl solution to cleave the thrombin from the aptasensor. PMID:20378327

  4. NEAR-IR DIRECT DETECTION OF WATER VAPOR IN TAU BOÖTIS b

    SciTech Connect

    Lockwood, Alexandra C.; Johnson, John A.; Blake, Geoffrey A.; Bender, Chad F.; Richert, Alexander J. W.; Carr, John S.; Barman, Travis

    2014-03-10

    We use high dynamic range, high-resolution L-band spectroscopy to measure the radial velocity (RV) variations of the hot Jupiter in the τ Boötis planetary system. The detection of an exoplanet by the shift in the stellar spectrum alone provides a measure of the planet's minimum mass, with the true mass degenerate with the unknown orbital inclination. Treating the τ Boo system as a high flux ratio double-lined spectroscopic binary permits the direct measurement of the planet's true mass as well as its atmospheric properties. After removing telluric absorption and cross-correlating with a model planetary spectrum dominated by water opacity, we measure a 6σ detection of the planet at K{sub p} = 111 ± 5 km s{sup –1}, with a 1σ upper limit on the spectroscopic flux ratio of 10{sup –4}. This RV leads to a planetary orbital inclination of i=45{sub −4}{sup +3}° and a mass of M{sub P}=5.90{sub −0.20}{sup +0.35} M{sub Jup}. We report the first detection of water vapor in the atmosphere of a non-transiting hot Jupiter, τ Boo b.

  5. Disposable amperometric magneto-immunosensor for direct detection of tetracyclines antibiotics residues in milk.

    PubMed

    Conzuelo, Felipe; Gamella, María; Campuzano, Susana; Reviejo, A Julio; Pingarrón, José M

    2012-08-01

    The preparation and performance of a disposable amperometric magneto-immunosensor, involving the use of a selective capture antibody immobilized on the surface of protein G-functionalized magnetic beads (ProtG-MBs) and screen-printed carbon electrodes (SPCEs), for the specific detection and quantification of tetracyclines (TCs) residues in milk is reported. A direct competitive immunoassay using a tracer with horseradish peroxidase (HRP) for the enzymatic labeling was performed. The amperometric response measured at -0.2 V vs. the silver pseudo-reference electrode of the SPCE upon the addition of H(2)O(2) in the presence of hydroquinone (HQ) as redox mediator was used as transduction signal. The developed methodology showed very low limits of detection (in the low ppb level) for 4 tetracycline antibiotics tested in untreated milk samples, and a good selectivity against other antibiotic residues frequently detected in milk and dairy products. The usefulness of the magneto-immunosensor was demonstrated by analyzing UHT whole milk samples spiked with 44 ng mL(-1) tetracycline (TC) as well as a reference milk containing a certified oxytetracycline (OTC) content. These features, together with the short analysis time (30 min), the simplicity, and easy automation and miniaturization of the required instrumentation make the developed methodology a promising alternative in the development of devices for on-site analysis.

  6. The Detection System for Existence and Direction of Emergency Vehicle using Microphone on-Vehicle

    NASA Astrophysics Data System (ADS)

    Otsuka, Shinichiro; Hara, Hironori; Ozawa, Shinji

    Problem may arise when the drivers are unable to notice or late in noticing emergency vehicles due to the sealing nature of the vehicles, masking by the car audio system or car navigation operation, which poses a threat for common vehicles and emergency vehicles to collide at many crossing. Every minute, problem may arise at every crossing and it is dangerous to wait for the completion of the information infrastructure system, which requires suitable cost and time. Therefore, we propose a system for common vehicles, which detects emergency vehicles using microphone on-vehicle and produce warning information to the driver. In this research, our focus is for “Ambulance", “Fire Truck" and “Police Car". The siren for these vehicles is detected by means of a microphone on-vehicle. This project utilizes two microphones to in order to detect the direction in which incoming emergency vehicles are present. The system, which we propose, must be helpful to response quickly to emergency and rescue activities.

  7. A new electrochemically active-inactive switching aptamer molecular beacon to detect thrombin directly in solution.

    PubMed

    Cheng, Guifang; Shen, Bijun; Zhang, Fan; Wu, Jikui; Xu, Ying; He, Pingang; Fang, Yuzhi

    2010-06-15

    A new electrochemical aptamer molecular beacon (MB) was designed by the carminic acid (CA) covalently linking at the each end of a special single-stranded stem-loop shaped oligonucleotide and named as CAs-MB. CA is an electrochemically active molecule and two CA molecules at the ends of molecular beacon stem were closed enough to associate each other to be as CA dimer. The dimer was electrochemically inactive. It separated into two CA monomers and produced the electrochemical signal while CAs-MB combined with target. In this protocol, the detection strategy of CAs-MB for thrombin is based on electrochemical active-inactive switching between monomer and dimer forms of CA. In order to enhance the electrochemical signal, magnetic nanobeads (MNB) was applied by connecting CAs-MB with MNB through a duplex of DNA. With the magnetic enrichment, the detection limit for thrombin reached to 42.4 pM. The experiment results showed that this type of electrochemical active-inactive switching aptamer molecular beacon allowed the direct detection of target proteins in the solution with no requirement of removing uncombined CAs-MB. Besides, CAs-MB/MNB can be easily regenerated by using 2M NaCl solution to cleave the thrombin from the aptasensor.

  8. Directed Design of Experiments for Validating Probability of Detection Capability of NDE Systems (DOEPOD)

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.

    2015-01-01

    Directed Design of Experiments for Validating Probability of Detection Capability of NDE Systems (DOEPOD) Manual v.1.2 The capability of an inspection system is established by applications of various methodologies to determine the probability of detection (POD). One accepted metric of an adequate inspection system is that there is 95% confidence that the POD is greater than 90% (90/95 POD). Design of experiments for validating probability of detection capability of nondestructive evaluation (NDE) systems (DOEPOD) is a methodology that is implemented via software to serve as a diagnostic tool providing detailed analysis of POD test data, guidance on establishing data distribution requirements, and resolving test issues. DOEPOD demands utilization of observance of occurrences. The DOEPOD capability has been developed to provide an efficient and accurate methodology that yields observed POD and confidence bounds for both Hit-Miss or signal amplitude testing. DOEPOD does not assume prescribed POD logarithmic or similar functions with assumed adequacy over a wide range of flaw sizes and inspection system technologies, so that multi-parameter curve fitting or model optimization approaches to generate a POD curve are not required. DOEPOD applications for supporting inspector qualifications is included.

  9. Digital quantification of miRNA directly in plasma using integrated comprehensive droplet digital detection.

    PubMed

    Zhang, Kaixiang; Kang, Dong-Ku; Ali, M Monsur; Liu, Linan; Labanieh, Louai; Lu, Mengrou; Riazifar, Hamidreza; Nguyen, Thi N; Zell, Jason A; Digman, Michelle A; Gratton, Enrico; Li, Jinghong; Zhao, Weian

    2015-11-01

    Quantification of miRNAs in blood can be potentially used for early disease detection, surveillance monitoring and drug response evaluation. However, quantitative and robust measurement of miRNAs in blood is still a major challenge in large part due to their low concentration and complicated sample preparation processes typically required in conventional assays. Here, we present the 'Integrated Comprehensive Droplet Digital Detection' (IC 3D) system where the plasma sample containing target miRNAs is encapsulated into microdroplets, enzymatically amplified and digitally counted using a novel, high-throughput 3D particle counter. Using Let-7a as a target, we demonstrate that IC 3D can specifically quantify target miRNA directly from blood plasma at extremely low concentrations ranging from 10s to 10 000 copies per mL in ≤3 hours without the need for sample processing such as RNA extraction. Using this new tool, we demonstrate that target miRNA content in colon cancer patient blood is significantly higher than that in healthy donor samples. Our IC 3D system has the potential to introduce a new paradigm for rapid, sensitive and specific detection of low-abundance biomarkers in biological samples with minimal sample processing. PMID:26387763

  10. Comparison of immunohistochemistry, electron microscopy, and direct fluorescent antibody test for the detection of bovine coronavirus.

    PubMed

    Dar, A M; Kapil, S; Goyal, S M

    1998-04-01

    Bovine coronavirus (BCV) is 1 of the major causes of calf diarrhea and has also been implicated in respiratory infections of young calves and winter dysentery of adult cattle. Currently, transmission electron microscopy (TEM), direct fluorescent antibody (DFA), and enzyme-linked immunosorbent assay (ELISA) techniques are considered standard methods for the diagnosis of BCV infection. However, these techniques are not useful if fresh tissues and intestinal contents are not available for examination. The detection of viral antigens in formalin-fixed, paraffin-embedded tissues using immunohistochemistry (IHC) is a suitable alternative. In the present study, 166 tissue specimens were tested by IHC for the presence of BCV. These tissues were from animals whose feces were positive for rotavirus and/or coronavirus by TEM. Some of these samples were also tested by DFA. Thus, TEM, DFA, and IHC were compared for the detection of BCV. There was 56% agreement among the 3 methods (overall kappa = 0.368). When IHC was compared with TEM, 78% agreement was observed (kappa = 0.475). Similarly, IHC and DFA had 64% agreement (kappa = 0.277). These kappa values indicate a moderate degree of agreement between IHC and TEM; agreement between IHC and DFA was fair. The results of this study indicate that IHC may be a suitable adjunct for the detection of BCV because of its simplicity, ease of use, and relatively close correlation with TEM results. PMID:9576342

  11. GEM-based TPC with CCD imaging for directional dark matter detection

    NASA Astrophysics Data System (ADS)

    Phan, N. S.; Lauer, R. J.; Lee, E. R.; Loomba, D.; Matthews, J. A. J.; Miller, E. H.

    2016-11-01

    The most mature directional dark matter experiments at present all utilize low-pressure gas Time Projection Chamber (TPC) technologies. We discuss some of the challenges for this technology, for which balancing the goal of achieving the best sensitivity with that of cost effective scale-up requires optimization over a large parameter space. Critical for this are the precision measurements of the fundamental properties of both electron and nuclear recoil tracks down to the lowest detectable energies. Such measurements are necessary to provide a benchmark for background discrimination and directional sensitivity that could be used for future optimization studies for directional dark matter experiments. In this paper we describe a small, high resolution, high signal-to-noise GEM-based TPC with a 2D CCD readout designed for this goal. The performance of the detector was characterized using alpha particles, X-rays, gamma-rays, and neutrons, enabling detailed measurements of electron and nuclear recoil tracks. Stable effective gas gains of greater than 1 × 105 were obtained in 100 Torr of pure CF4 by a cascade of three standard CERN GEMs each with a 140 μm pitch. The high signal-to-noise and sub-millimeter spatial resolution of the GEM amplification and CCD readout, together with low diffusion, allow for excellent background discrimination between electron and nuclear recoils down below ∼10 keVee (∼23 keVr fluorine recoil). Even lower thresholds, necessary for the detection of low mass WIMPs for example, might be achieved by lowering the pressure and utilizing full 3D track reconstruction. These and other paths for improvements are discussed, as are possible fundamental limitations imposed by the physics of energy loss.

  12. Detection of particle flow patterns in tumor by directional spatial frequency analysis

    NASA Astrophysics Data System (ADS)

    Russell, Stewart; Camara, Hawa; Shi, Lingyan; Hoopes, P. Jack; Kaufman, Peter; Pogue, Brian; Alfano, Robert

    2016-04-01

    Drug delivery to tumors is well known to be chaotic and limited, partly from dysfunctional vasculature, but also because of microscopic regional variations in composition. Modeling the of transport of nanoparticle therapeutics, therefore must include not only a description of vascular permeability, but also of the movement of the drug as suspended in tumor interstitial fluid (TIF) once it leaves the blood vessel. Understanding of this area is limited because we currently lack the tools and analytical methods to characterize it. We have previously shown that directional anisotropy of drug delivery can be detected using Directional Fourier Spatial Frequency (DFSF) Analysis. Here we extend this approach to generate flow line maps of nanoparticle transport in TIF relative to tumor ultrastructure, and show that features of tumor spatial heterogeneity can be identified that are directly related to local flow isometries. The identification of these regions of limited flow may be used as a metric for determining response to therapy, or for the optimization of adjuvant therapies such as radiation pre-treatment, or enzymatic degradation.

  13. Markov chain Monte Carlo analysis to constrain dark matter properties with directional detection

    SciTech Connect

    Billard, J.; Mayet, F.; Santos, D.

    2011-04-01

    Directional detection is a promising dark matter search strategy. Indeed, weakly interacting massive particle (WIMP)-induced recoils would present a direction dependence toward the Cygnus constellation, while background-induced recoils exhibit an isotropic distribution in the Galactic rest frame. Taking advantage of these characteristic features, and even in the presence of a sizeable background, it has recently been shown that data from forthcoming directional detectors could lead either to a competitive exclusion or to a conclusive discovery, depending on the value of the WIMP-nucleon cross section. However, it is possible to further exploit these upcoming data by using the strong dependence of the WIMP signal with: the WIMP mass and the local WIMP velocity distribution. Using a Markov chain Monte Carlo analysis of recoil events, we show for the first time the possibility to constrain the unknown WIMP parameters, both from particle physics (mass and cross section) and Galactic halo (velocity dispersion along the three axis), leading to an identification of non-baryonic dark matter.

  14. Detection of magnetic fields in both B-type components of the ɛ Lupi system: a new constraint on the origin of fossil fields?

    NASA Astrophysics Data System (ADS)

    Shultz, M.; Wade, G. A.; Alecian, E.; BinaMIcS Collaboration

    2015-11-01

    High-resolution circular spectropolarimetric observations, obtained with ESPaDOnS in the context of the BinaMIcS Large Program, have revealed a magnetic field in the B3V secondary component of the SB2 binary system ɛ Lupi (B2/B3). As the B2V primary is already known to be magnetic, this is the first detection of a magnetic field in both components of an early-type binary system. The longitudinal magnetic field of the primary is ˜ -200 G; that of the secondary ˜ +100 G. Observations can be approximately reproduced by a model assuming the magnetic axes of the two stars are anti-aligned, and roughly parallel to their respective rotation axes. Estimated magnetospheric radii indicate a high probability that their magnetospheres are interacting. As many of the arguments for the different proposed formation scenarios of fossil magnetic fields rely upon evidence drawn from investigations of close binaries, in particular the rarity of magnetic ABO stars in close binaries and the previous absence of any known close binary with two magnetic, massive stars, this discovery may be an important new constraint on the origin of fossil magnetic fields.

  15. Directional neutron detectors for use with 14 MeV neutrons :fiber scintillation methods for directional neutron detection.

    SciTech Connect

    Sunnarborg, Duane A.; Peel, Justin D.; Mascarenhas, Nicholas; Mengesha, Wondwosen

    2005-10-01

    Current Joint Test Assembly (JTA) neutron monitors rely on knock-on proton type detectors that are susceptible to X-rays and low energy gamma rays. We investigated two novel plastic scintillating fiber directional neutron detector prototypes. One prototype used a fiber selected such that the fiber width was less than 2.1mm which is the range of a proton in plastic. The difference in the distribution of recoil proton energy deposited in the fiber was used to determine the incident neutron direction. The second prototype measured both the recoil proton energy and direction. The neutron direction was determined from the kinematics of single neutron-proton scatters. This report describes the development and performance of these detectors.

  16. The feasibility of detecting cerebral blood flow direction using the indocyanine green video angiography.

    PubMed

    Murai, Yasuo; Nakagawa, Syunsuke; Matano, Fumihiro; Shirokane, Kazutaka; Teramoto, Akira; Morita, Akio

    2016-10-01

    The intraoperative confirmation of blood flow direction is necessary in cerebral vascular surgery. Using indocyanine green video angiography (ICG-VAG) with the FLOW 800 system, we examined the transit time of the blood vessel of interest and semiquantitatively evaluated the delay time (T1/2max) from indocyanine green (ICG) injection into the donor artery in reconstructive surgery and the middle cerebral artery (MCA) in aneurysmal surgery. The direction of cerebral blood flow (CBF), which can often be confirmed by ICG-VAG, may be more difficult to determine with faster blood flow. Here, we report our findings regarding the feasibility of detecting CBF direction using the FLOW 800 system. Twenty patients undergoing superficial temporal artery (STA) to MCA anastomosis for carotid occlusive disease and 13 patients with a small MCA aneurysm clipping were evaluated using the T1/2max, semiquantitative method with the FLOW 800 system. In STA-MCA anastomosis cases, the regions of interest (ROIs) included: the proximal donor STA and a region more than 10 mm on the distal side of the donor STA near the anastomosis site. In MCA aneurysms, the ROIs included the proximal M1 and distal M2 sides of the MCA aneurysm. T1/2max was significantly shorter for the proximal sites compared to the distal sites for all subjects (ps < 0.01). T1/2max was shorter for all subjects in the proximal sites. The direction of CBF can be determined using the FLOW 800 system.

  17. Halo-independent tests of dark matter direct detection signals: local DM density, LHC, and thermal freeze-out

    SciTech Connect

    Blennow, Mattias; Herrero-Garcia, Juan; Schwetz, Thomas; Vogl, Stefan

    2015-08-19

    From an assumed signal in a Dark Matter (DM) direct detection experiment a lower bound on the product of the DM-nucleon scattering cross section and the local DM density is derived, which is independent of the local DM velocity distribution. This can be combined with astrophysical determinations of the local DM density. Within a given particle physics model the bound also allows a robust comparison of a direct detection signal with limits from the LHC. Furthermore, the bound can be used to formulate a condition which has to be fulfilled if the particle responsible for the direct detection signal is a thermal relic, regardless of whether it constitutes all DM or only part of it. We illustrate the arguments by adopting a simplified DM model with a Z{sup ′} mediator and assuming a signal in a future xenon direct detection experiment.

  18. Direct Detection of Pure ac Spin Current by X-Ray Pump-Probe Measurements.

    PubMed

    Li, J; Shelford, L R; Shafer, P; Tan, A; Deng, J X; Keatley, P S; Hwang, C; Arenholz, E; van der Laan, G; Hicken, R J; Qiu, Z Q

    2016-08-12

    Despite recent progress in spin-current research, the detection of spin current has mostly remained indirect. By synchronizing a microwave waveform with synchrotron x-ray pulses, we use the ferromagnetic resonance of the Py (Ni_{81}Fe_{19}) layer in a Py/Cu/Cu_{75}Mn_{25}/Cu/Co multilayer to pump a pure ac spin current into the Cu_{75}Mn_{25} and Co layers, and then directly probe the spin current within the Cu_{75}Mn_{25} layer and the spin dynamics of the Co layer by x-ray magnetic circular dichroism. This element-resolved pump-probe measurement unambiguously identifies the ac spin current in the Cu_{75}Mn_{25} layer. PMID:27563981

  19. Direct detection of resonant electron pitch angle scattering by whistler waves in a laboratory plasma.

    PubMed

    Van Compernolle, B; Bortnik, J; Pribyl, P; Gekelman, W; Nakamoto, M; Tao, X; Thorne, R M

    2014-04-11

    Resonant interactions between energetic electrons and whistler mode waves are an essential ingredient in the space environment, and in particular in controlling the dynamic variability of Earth's natural radiation belts, which is a topic of extreme interest at the moment. Although the theory describing resonant wave-particle interaction has been present for several decades, it has not been hitherto tested in a controlled laboratory setting. In the present Letter we report on the first laboratory experiment to directly detect resonant pitch angle scattering of energetic (∼keV) electrons due to whistler mode waves. We show that the whistler mode wave deflects energetic electrons at precisely the predicted resonant energy, and that varying both the maximum beam energy, and the wave frequency, alters the energetic electron beam very close to the resonant energy.

  20. Atmospheric aerosol and molecular backscatter imaging effects on direct detection LADAR

    NASA Astrophysics Data System (ADS)

    Youmans, Douglas G.

    2015-05-01

    Backscatter from atmospheric aerosols and molecular nitrogen and oxygen causes "clutter" noise in direct detection ladar applications operating within the atmosphere. The backscatter clutter is more pronounced in multiple pulse, high PRF ladars where pulse-averaging is used to increase operating range. As more and more pulses are added to the wavetrain the backscatter increases. We analyze the imaging of a transmitted Gaussian laser-mode multi-pulse wave-train scatteried off of aerosols and molecules at the focal plane including angular-slew rate resulting from optical tracking, angular lead-angle, and bistatic-optics spatial separation. The defocused backscatter images, from those pulses closest to the receiver, are analyzed using a simple geometrical optics approximation. Methods for estimating the aerosol number density versus altitude and the volume backscatter coefficient of the aerosols are also discussed.

  1. Effect of gravitational focusing on annual modulation in dark-matter direct-detection experiments.

    PubMed

    Lee, Samuel K; Lisanti, Mariangela; Peter, Annika H G; Safdi, Benjamin R

    2014-01-10

    The scattering rate in dark-matter direct-detection experiments should modulate annually due to Earth's orbit around the Sun. The rate is typically thought to be extremized around June 1, when the relative velocity of Earth with respect to the dark-matter wind is maximal. We point out that gravitational focusing can alter this modulation phase. Unbound dark-matter particles are focused by the Sun's gravitational potential, affecting their phase-space density in the lab frame. Gravitational focusing can result in a significant overall shift in the annual-modulation phase, which is most relevant for dark matter with low scattering speeds. The induced phase shift for light O(10)  GeV dark matter may also be significant, depending on the threshold energy of the experiment.

  2. Electroweak symmetry breaking from the soft portal into dark matter and prediction for direct detection.

    PubMed

    Kadastik, Mario; Kannike, Kristjan; Racioppi, Antonio; Raidal, Martti

    2010-05-21

    Scalar dark matter (DM) can have dimensionful coupling to the Higgs boson-the soft portal into DM-which is predicted to be unsuppressed by the underlying SO(10) grand unified theory (GUT). The dimensionful coupling can be large, μ/v>1, without spoiling the perturbativity of low energy theory up to the GUT scale. We show that the soft portal into DM naturally triggers radiative electroweak symmetry breaking (EWSB) via large 1-loop DM corrections to the effective potential. In this scenario, EWSB, the DM thermal freeze-out cross section, and DM scattering on nuclei are all dominated by the same coupling, predicting the DM mass range to be 700  GeVdirect detection cross section is predicted to be just below the present experimental bounds.

  3. First direct sulfuric acid detection in the exhaust plume of a jet aircraft in flight

    NASA Astrophysics Data System (ADS)

    Curtius, J.; Sierau, B.; Arnold, F.; Baumann, R.; Busen, R.; Schulte, P.; Schumann, U.

    Sulfuric acid (SA) was for the first time directly detected in the exhaust plume of a jet aircraft in flight. The measurements were made by a novel aircraft-based VACA (Volatile Aerosol Component Analyzer) instrument of MPI-K Heidelberg while the research aircraft Falcon was chasing another research aircraft ATTAS. The VACA measures the total SA in the gas and in volatile submicron aerosol particles. During the chase the engines of the ATTAS alternatively burned sulfur-poor and sulfur-rich fuel. In the sulfur-rich plume very marked enhancements of total SA were observed of up to 1300 pptv which were closely correlated with ΔCO2 and ΔT and were far above the local ambient atmospheric background-level of typically 15-50 pptv. Our observations indicate a lower limit for the efficiency ɛ for fuel-sulfur conversion to SA of 0.34 %.

  4. Hypercharged dark matter and direct detection as a probe of reheating.

    PubMed

    Feldstein, Brian; Ibe, Masahiro; Yanagida, Tsutomu T

    2014-03-14

    The lack of new physics at the LHC so far weakens the argument for TeV scale thermal dark matter. On the other hand, heavier, nonthermal dark matter is generally difficult to test experimentally. Here we consider the interesting and generic case of hypercharged dark matter, which can allow for heavy dark matter masses without spoiling testability. Planned direct detection experiments will be able to see a signal for masses up to an incredible 1010  GeV, and this can further serve to probe the reheating temperature up to about 109  GeV, as determined by the nonthermal dark matter relic abundance. The Z-mediated nature of the dark matter scattering may be determined in principle by comparing scattering rates on different detector nuclei, which in turn can reveal the dark matter mass. We will discuss the extent to which future experiments may be able to make such a determination.

  5. Combined discrete Fourier transform precoding and clipping using direct detection optical OFDM

    NASA Astrophysics Data System (ADS)

    Wang, Zhongpeng; Chen, Shoufa

    2015-07-01

    We propose and demonstrate experimentally the bit error rate (BER) performance of intensity modulation with direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system by combining discrete Fourier transform (DFT) precoding with clipping. The experimental results show that the received sensitivity at a BER of 10-4 for a 12 Gs/s DFT-precoded and clipped OFDM signal and after 100-km standard single-mode fiber transmission has been improved by 3.5 dB when compared with the original OFDM systems in the SMF link, and by 2.5 dB when compared with compared with the DFT-precoded OFDM signals. When compared with the DFT-precoded QPSK OFDM signal, the DFT-precoded and clipped OFDM QPSK signal can achieve approximately 4.5 dB of peak-to-average power ratio (PAPR) reduction at a complementary cumulative distribution functional value of 10-3.

  6. DIRECT DETECTION OF SEASONAL CHANGES ON TRITON WITH HUBBLE SPACE TELESCOPE

    SciTech Connect

    Bauer, James M.; Buratti, Bonnie J.; Mosher, Joel A.; Hicks, Michael D.; Goguen, Jay D.; Li Jianyang; Schmidt, Britney E. E-mail: Bonnie.Buratti@jpl.nasa.go E-mail: hicksm@scn.jpl.nasa.go E-mail: jyli@astro.umd.ed

    2010-11-01

    Triton is one of the few bodies in the solar system with observed cryo-volcanic activity, in the form of plumes at its south pole, which suggests large-scale surface volatile transport over time. Triton's large variations in obliquity have motivated prior predictions of changing atmospheric column densities of several orders of magnitude, driven by seasonal evaporation of surface volatiles. Using the Hubble Space Telescope, we directly imaged Triton's surface and have detected large-scale differences in increased and decreased reflectance when compared with Voyager data at UV, visual, and methane-band wavelengths. Our surface map shows regions of increased brightness at near-equatorial latitudes and near the Neptune-facing side, and darkened regions near longitudes of {+-}180{sup 0}, indicating the presence of ongoing seasonal volatile transport.

  7. Investigation of PMD in direct-detection optical OFDM with zero padding.

    PubMed

    Li, Xiang; Alphones, Arokiaswami; Zhong, Wen-De; Yu, Changyuan

    2013-09-01

    We investigate the polarization-mode dispersion (PMD) effect of zero padding OFDM (ZP-OFDM) in direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) systems. We first study the conventional equalization method for ZP-OFDM. Then an equalization method based on sorted QR decomposition is proposed to further improve the performance. It is found that the performance improvement of ZP-OFDM is due to the frequency domain oversampling (FDO) induced inter-carrier interference (ICI). Numerical simulation results show that compared with cyclic prefix OFDM (CP-OFDM), ZP-OFDM has a significantly higher tolerance to PMD in DDO-OFDM systems when the channel spectral nulls occur at certain differential group delay (DGD) values. PMID:24103957

  8. A comparative study of optimum and suboptimum direct-detection laser ranging receivers

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.

    1978-01-01

    A summary of previously proposed receiver strategies for direct-detection laser ranging receivers is presented. Computer simulations are used to compare performance of candidate implementation strategies in the 1- to 100-photoelectron region. Under the condition of no background radiation, the maximum-likelihood and minimum mean-square error estimators were found to give the same performance for both bell-shaped and rectangular optical-pulse shapes. For signal energies greater than 100 photoelectrons, the root-mean-square range error is shown to decrease as Q to the -1/2 power for bell-shaped pulses and Q to the -1 power for rectangular pulses, where Q represents the average pulse energy. Of several receiver implementations presented, the matched-filter peak detector was found to be preferable. A similar configuration, using a constant-fraction discriminator, exhibited a signal-level dependent time bias.

  9. Direct Detection of Pure ac Spin Current by X-Ray Pump-Probe Measurements

    NASA Astrophysics Data System (ADS)

    Li, J.; Shelford, L. R.; Shafer, P.; Tan, A.; Deng, J. X.; Keatley, P. S.; Hwang, C.; Arenholz, E.; van der Laan, G.; Hicken, R. J.; Qiu, Z. Q.

    2016-08-01

    Despite recent progress in spin-current research, the detection of spin current has mostly remained indirect. By synchronizing a microwave waveform with synchrotron x-ray pulses, we use the ferromagnetic resonance of the Py (Ni81Fe19 ) layer in a Py /Cu /Cu75Mn25/Cu /Co multilayer to pump a pure ac spin current into the Cu75Mn25 and Co layers, and then directly probe the spin current within the Cu75Mn25 layer and the spin dynamics of the Co layer by x-ray magnetic circular dichroism. This element-resolved pump-probe measurement unambiguously identifies the ac spin current in the Cu75Mn25 layer.

  10. 2-Micron Pulsed Direct Detection IPDA Lidar for Atmospheric CO2 Measurement

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Petros, Mulugeta; Refaat, Tamer; Reithmaier, Karl; Remus, Ruben; Singh, Upendra; Johnson, Will; Boyer, Charlie; Fay, James; Johnston, Susan; Murchison, Luke

    2014-01-01

    A 2-micron high energy, pulsed Integrated Path Differential Absorption (IPDA) lidar has been developed for atmospheric CO2 measurements. Development of this lidar heavily leverages the 2-micron laser technologies developed in LaRC over the last decade. The high pulse energy, direct detection lidar operating at CO2 2-micron absorption band provides an alternate approach to measure CO2 concentrations. This new 2-micron pulsed IPDA lidar has been flown in spring of this year for total ten flights with 27 flight hours. It is able to make measurements of the total amount of atmospheric CO2 from the aircraft to the ground or cloud. It is expected to provide high-precision measurement capability by unambiguously eliminating contamination from aerosols and clouds that can bias the IPDA measurement.

  11. High speed QPPM direct detection optical communication receivers for FSDD intersatellite links

    NASA Technical Reports Server (NTRS)

    Davidson, Frederic M.; Sun, Xiaoli

    1993-01-01

    This final report consists of four separate reports, one for each project involved in this contract. The first report is entitled '325 Mbps QPPM (quaternary pulse position modulation) Direct Detection Free Space Optical Communication Encoder and Receiver,' which was our primary work. The second report is entitled 'Test Results of the 325 Mbps QPPM High Speed Data Transmission GaAs ASICs,' which describes our work in connection with Galaxy Microsystems, Inc. who produced these ASICs for NASA. The third report, 'Receiver Performance Analysis of BPPM Optical Communication Systems Using 1.3 micron Wavelength Transmitter and InGaAs PIN Photodiodes,' was prepared at the request of the NASA/Photonics Branch for their efforts in upgrading the 1773 optical fiber data bus. The fourth report, 'Photomultiplier Tubes for Use at 1.064 micron Wavelength,' was also prepared at the request of the NASA/Photonics Branch as a research project.

  12. NASA/GSFC program in direct detection optical communications for intersatellite links

    NASA Technical Reports Server (NTRS)

    Fitzmaurice, M.; Bruno, R.

    1989-01-01

    NASA-Goddard has undertaken the development of direct-detection optical communications for space applications at the Gbps data rate channel capability level. The primary challenges to optical communications designers lie in the development of reliable optical power sources, as well as of high performance pointing/acquisition/tracking systems required by the narrow widths of the transmitted optical beams. GaAlAs diodes and their arrays are currently the most attractive technology for optical transmitters; pioneering work has also been conducted on dichroic and grating techniques for combining the power of several laser diodes. Attention is given to the performance obtained for an optical link acquisition and submicroradian tracking/pointing system.

  13. Directed Design of Experiments for Validating Probability of Detection Capability of a Testing System

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R. (Inventor)

    2012-01-01

    A method of validating a probability of detection (POD) testing system using directed design of experiments (DOE) includes recording an input data set of observed hit and miss or analog data for sample components as a function of size of a flaw in the components. The method also includes processing the input data set to generate an output data set having an optimal class width, assigning a case number to the output data set, and generating validation instructions based on the assigned case number. An apparatus includes a host machine for receiving the input data set from the testing system and an algorithm for executing DOE to validate the test system. The algorithm applies DOE to the input data set to determine a data set having an optimal class width, assigns a case number to that data set, and generates validation instructions based on the case number.

  14. Direct Detection Doppler Lidar Wind Measurements Obtained During the 2002 International H2O Project (IHOP)

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce; Li, Steven; Chen, Huai-Lin; Comer, Joseph; Mathur, Savyasachee; Bobler, Jeremy

    2005-01-01

    The Goddard Lidar Observatory for Winds (GLOW) is a mobile Doppler lidar system that uses direct detection techniques for profiling winds in the troposphere and lower stratosphere. In May and June of 2002 GLOW was deployed to the Southern Great Plains of the US to participate in the International H2O Project (IHOP). GLOW was located at the Homestead profiling site in the Oklahoma panhandle about 15 km east of the SPOL radar. Several other Goddard lidars, the Scanning Raman Lidar (SRL) and HARLIE, as well as radars and passive instruments were permanently operated from the Homestead site during the IHOP campaign providing a unique cluster of observations. During the IHOP observation period (May 14, 2002 to June 25, 2002) over 240 hours of wind profile measurements were obtained with GLOW. In this paper we will describe the GLOW instrument as it was configured for the IHOP campaign and we will present examples of wind profiles obtained.

  15. Electrochemical direct immobilization of DNA sequences for label-free herpes virus detection

    NASA Astrophysics Data System (ADS)

    Tam, Phuong Dinh; Trung, Tran; Tuan, Mai Anh; Chien, Nguyen Duc

    2009-09-01

    DNA sequences/bio-macromolecules of herpes virus (5'-AT CAC CGA CCC GGA GAG GGA C-3') were directly immobilized into polypyrrole matrix by using the cyclic voltammetry method, and grafted onto arrays of interdigitated platinum microelectrodes. The morphology surface of the obtained PPy/DNA of herpes virus composite films was investigated by a FESEM Hitachi-S 4800. Fourier transform infrared spectroscopy (FTIR) was used to characterize the PPy/DNA film and to study the specific interactions that may exist between DNA biomacromolecules and PPy chains. Attempts are made to use these PPy/DNA composite films for label-free herpes virus detection revealed a response time of 60 s in solutions containing as low as 2 nM DNA concentration, and self life of six months when immerged in double distilled water and kept refrigerated.

  16. Electronic polarization-division demultiplexing based on digital signal processing in intensity-modulation direct-detection optical communication systems.

    PubMed

    Kikuchi, Kazuro

    2014-01-27

    We propose a novel configuration of optical receivers for intensity-modulation direct-detection (IM · DD) systems, which can cope with dual-polarization (DP) optical signals electrically. Using a Stokes analyzer and a newly-developed digital signal-processing (DSP) algorithm, we can achieve polarization tracking and demultiplexing in the digital domain after direct detection. Simulation results show that the power penalty stemming from digital polarization manipulations is negligibly small.

  17. Direct magnetic resonance detection of myelin and prospects for quantitative imaging of myelin density

    PubMed Central

    Wilhelm, Michael J.; Ong, Henry H.; Tsai, Ping-Huei; Hackney, David B.; Wehrli, Felix W.

    2012-01-01

    Magnetic resonance imaging has previously demonstrated its potential for indirectly mapping myelin density, either by relaxometric detection of myelin water or magnetization transfer. Here, we investigated whether myelin can be detected and possibly quantified directly. We identified the spectrum of myelin in the spinal cord in situ as well as in myelin lipids extracted via a sucrose gradient method, and investigated its spectral properties. High-resolution solution NMR spectroscopy showed the extract composition to be in agreement with myelin’s known chemical make-up. The 400-MHz 1H spectrum of the myelin extract, at 20 °C (room temperature) and 37 °C, consists of a narrow water resonance superimposed on a broad envelope shifted ∼3.5 ppm upfield, suggestive of long-chain methylene protons. Superimposed on this signal are narrow components resulting from functional groups matching the chemical shifts of the constituents making up myelin lipids. The spectrum could be modeled as a sum of super-Lorentzians with a T2* distribution covering a wide range of values (0.008–26 ms). Overall, there was a high degree of similarity between the spectral properties of extracted myelin lipids and those found in neural tissue. The normalized difference spectrum had the hallmarks of membrane proteins, not present in the myelin extract. Using 3D radially ramp-sampled proton MRI, with a combination of adiabatic inversion and echo subtraction, the feasibility of direct myelin imaging in situ is demonstrated. Last, the integrated signal from myelin suspensions is shown, both spectroscopically and by imaging, to scale with concentration, suggesting the potential for quantitative determination of myelin density. PMID:22628562

  18. Atypical sensors for direct and rapid neuronal detection of bacterial pathogens.

    PubMed

    Lim, Ji Yeon; Choi, Seung-In; Choi, Geunyeol; Hwang, Sun Wook

    2016-03-09

    Bacterial infection can threaten the normal biological functions of a host, often leading to a disease. Hosts have developed complex immune systems to cope with the danger. Preceding the elimination of pathogens, selective recognition of the non-self invaders is necessary. At the forefront of the body's defenses are the innate immune cells, which are equipped with particular sensor molecules that can detect common exterior patterns of invading pathogens and their secreting toxins as well as with phagocytic machinery. Inflammatory mediators and cytokines released from these innate immune cells and infected tissues can boost the inflammatory cascade and further recruit adaptive immune cells to maximize the elimination and resolution. The nervous system also seems to interact with this process, mostly known to be affected by the inflammatory mediators through the binding of neuronal receptors, consequently activating neural circuits that tune the local and systemic inflammatory states. Recent research has suggested new contact points: direct interactions of sensory neurons with pathogens. Latest findings demonstrated that the sensory neurons not only share pattern recognition mechanisms with innate immune cells, but also utilize endogenous and exogenous electrogenic components for bacterial pathogen detection, by which the electrical firing prompts faster information flow than what could be achieved when the immune system is solely involved. As a result, rapid pain generation and active accommodation of the immune status occur. Here we introduced the sensory neuron-specific detector molecules for directly responding to bacterial pathogens and their signaling mechanisms. We also discussed extended issues that need to be explored in the future.

  19. Rapid Detection of Thrombin and Other Protease Activity Directly in Whole Blood

    NASA Astrophysics Data System (ADS)

    Yu, Johnson Chung Sing

    Thrombin is a serine protease that plays a key role in the clotting cascade to promote hemostasis following injury to the endothelium. From a clinical diagnostic perspective, in-vivo thrombin activity is linked to various blood clotting disorders, as well as cardiovascular disease (DVT, arteriosclerosis, etc). Thus, the ability to rapidly measure protease activity directly in whole blood will provide important new diagnostics, and clinical researchers with a powerful tool to further elucidate the relationship between circulating protease levels and disease. The ultimate goal is to design novel point of care (POC) diagnostic devices that are capable of monitoring protease activities directly in whole blood and biological sample. A charge-changing substrate specific to the thrombin enzyme was engineered and its functionality was confirmed by a series of experiments. This led to the preliminary design, construction, and testing of two device platforms deemed fully functional for the electrophoretic separation and focusing of charged peptide fragments. The concept of using the existing charge-changing substrate platform for bacterial protease detection was also investigated. Certain strains of E coli are associated with severe symptoms such as abdominal cramps, bloody diarrhea, and vomiting. The OmpT protease is expressed on the outer membrane of E coli and plays a role in the cleavage of antimicrobial peptides, the degradation of recombinant heterologous proteins, and the activation of plasminogen in the host. Thus, a synthetic peptide substrate specific to the OmpT protease was designed and modeled for the purpose of detecting E coli in biological sample.

  20. Direct exoplanet detection and characterization using the ANDROMEDA method: Performance on VLT/NaCo data

    NASA Astrophysics Data System (ADS)

    Cantalloube, F.; Mouillet, D.; Mugnier, L. M.; Milli, J.; Absil, O.; Gomez Gonzalez, C. A.; Chauvin, G.; Beuzit, J.-L.; Cornia, A.

    2015-10-01

    Context. The direct detection of exoplanets with high-contrast imaging requires advanced data processing methods to disentangle potential planetary signals from bright quasi-static speckles. Among them, angular differential imaging (ADI) permits potential planetary signals with a known rotation rate to be separated from instrumental speckles that are either statics or slowly variable. The method presented in this paper, called ANDROMEDA for ANgular Differential OptiMal Exoplanet Detection Algorithm, is based on a maximum likelihood approach to ADI and is used to estimate the position and the flux of any point source present in the field of view. Aims: In order to optimize and experimentally validate this previously proposed method, we applied ANDROMEDA to real VLT/NaCo data. In addition to its pure detection capability, we investigated the possibility of defining simple and efficient criteria for automatic point source extraction able to support the processing of large surveys. Methods: To assess the performance of the method, we applied ANDROMEDA on VLT/NaCo data of TYC-8979-1683-1 which is surrounded by numerous bright stars and on which we added synthetic planets of known position and flux in the field. In order to accommodate the real data properties, it was necessary to develop additional pre-processing and post-processing steps to the initially proposed algorithm. We then investigated its skill in the challenging case of a well-known target, β Pictoris, whose companion is close to the detection limit and we compared our results to those obtained by another method based on principal component analysis (PCA). Results: Application on VLT/NaCo data demonstrates the ability of ANDROMEDA to automatically detect and characterize point sources present in the image field. We end up with a robust method bringing consistent results with a sensitivity similar to the recently published algorithms, with only two parameters to be fine tuned. Moreover, the companion flux

  1. Layer-by-layer assembly of functionalized reduced graphene oxide for direct electrochemistry and glucose detection.

    PubMed

    Mascagni, Daniela Branco Tavares; Miyazaki, Celina Massumi; da Cruz, Nilson Cristino; de Moraes, Marli Leite; Riul, Antonio; Ferreira, Marystela

    2016-11-01

    We report an electrochemical glucose biosensor made with layer-by-layer (LbL) films of functionalized reduced graphene oxide (rGO) and glucose oxidase (GOx). The LbL assembly using positively and negatively charged rGO multilayers represents a simple approach to develop enzymatic biosensors. The electron transport properties of graphene were combined with the specificity provided by the enzyme. rGO was obtained and functionalized using chemical methods, being positively charged with poly(diallyldimethylammonium chloride) to form GPDDA, and negatively charged with poly(styrene sulfonate) to form GPSS. Stable aqueous dispersions of GPDDA and GPSS are easily obtained, enabling the growth of LbL films on various solid supports. The use of graphene in the immobilization of GOx promoted Direct Electron Transfer, which was evaluated by Cyclic Voltammetry. Amperometric measurements indicated a detection limit of 13.4μmol·L(-1) and sensitivity of 2.47μA·cm(-2)·mmol(-1)·L for glucose with the (GPDDA/GPSS)1/(GPDDA/GOx)2 architecture, whose thickness was 19.80±0.28nm, as determined by Surface Plasmon Resonance (SPR). The sensor may be useful for clinical analysis since glucose could be detected even in the presence of typical interfering agents and in real samples of a lactose-free milk and an electrolyte solution to prevent dehydration. PMID:27524075

  2. Direct electrochemical sensor for label-free DNA detection based on zero current potentiometry.

    PubMed

    Wu, Nai-ying; Gao, Wei; He, Xu-lun; Chang, Zhu; Xu, Mao-tian

    2013-01-15

    A direct electrochemical DNA biosensor based on zero current potentiometry was fabricated by immobilization of ssDNA onto gold nanoparticles (AuNPs) coated pencil graphite electrode (PGE). One ssDNA/AuNPs/PGE was connected in series between clips of working and counter electrodes of a potentiostat, and then immersed into the solution together with a reference electrode, establishing a novel DNA biosensor for specific DNA detection. The variation of zero current potential difference (ΔE(zcp)) before and after hybridization of the self-assembled probe DNA with the target DNA was used as a signal to characterize and quantify the target DNA sequence. The whole DNA biosensor fabrication process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy with the use of ferricyanide as an electrochemical redox indicator. Under the optimized conditions, ΔE(zcp) was linear with the concentrations of the complementary target DNA in the range from 10nM to 1μM, with a detection limit of 6.9nM. The DNA biosensor showed a good reproducibility and selectivity. Prepared DNA biosensor is facile and sensitive, and it eliminates the need of using exogenous reagents to monitor the oligonucleotides hybridization.

  3. APIC: Absolute Position Interfero Coronagraph for direct exoplanet detection: first laboratory results

    NASA Astrophysics Data System (ADS)

    Allouche, Fatmé; Glindemann, Andreas; Aristidi, Eric; Vakili, Farrokh

    2010-07-01

    For the detection and direct imaging of exoplanets, when the intensity ratio between a star and its orbiting planet can largely exceed 106, coronagraphic methods are mandatory. In 1996, a concept of achromatic interferocoronagraph (AIC) was presented by J. Gay and Y. Rabbia for the detection of very faint stellar companions, such as exoplanets. In an earlier paper, we presented a modified version of the AIC permitting to determine the relative position of these faint companions with respect to the parent star, a problem unsolved in the original design of the AIC. Our modification lied in the use of cylindrical lens doublets as field rotator. By placing two of them in one arm of the interferometric set-up of AIC, we destroyed the axis of symmetry induced by the AIC's original design. Our theoretical study, along with the numerical computations, presented then, and the preliminary test bench results aiming at validating the cylindrical lens doublet field rotation capability, presented in this paper, show that the axis of symmetry is destroyed when one of the cylindrical doublets is rotated around the optic axis.

  4. Direct-detection Free-space Laser Transceiver Test-bed

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Chen, Jeffrey R.; Dabney, Philip W.; Ferrara, Jeffrey F.; Fong, Wai H.; Martino, Anthony J.; McGarry Jan. F.; Merkowitz, Stephen M.; Principe, Caleb M.; Sun, Siaoli; Zagwodzki, Thomas W.

    2008-01-01

    NASA Goddard Space Flight Center is developing a direct-detection free-space laser communications transceiver test bed. The laser transmitter is a master-oscillator power amplifier (MOPA) configuration using a 1060 nm wavelength laser-diode with a two-stage multi-watt Ytterbium fiber amplifier. Dual Mach-Zehnder electro-optic modulators provide an extinction ratio greater than 40 dB. The MOPA design delivered 10-W average power with low-duty-cycle PPM waveforms and achieved 1.7 kW peak power. We use pulse-position modulation format with a pseudo-noise code header to assist clock recovery and frame boundary identification. We are examining the use of low-density-parity-check (LDPC) codes for forward error correction. Our receiver uses an InGaAsP 1 mm diameter photocathode hybrid photomultiplier tube (HPMT) cooled with a thermo-electric cooler. The HPMT has 25% single-photon detection efficiency at 1064 nm wavelength with a dark count rate of 60,000/s at -22 degrees Celsius and a single-photon impulse response of 0.9 ns. We report on progress toward demonstrating a combined laser communications and ranging field experiment.

  5. Direct-detection optical OFDM superchannel for long-reach PON using pilot regeneration.

    PubMed

    Hu, Rong; Yang, Qi; Xiao, Xiao; Gui, Tao; Li, Zhaohui; Luo, Ming; Yu, Shaohua; You, Shanhong

    2013-11-01

    We demonstrate a novel long-reach PON downstream scheme based on the regenerated pilot assisted direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) superchannel transmission. We use the optical comb source to form DDO-OFDM superchannel, and reserve the center carrier as a seed pilot. The seed pilot is further tracked and reused to generate multiple optical carriers at the local exchange. Each regenerated pilot carrier is selected to beat with an adjacent OFDM sub-band at ONU, so that the electrical bandwidth limitation can be much released compared to the conventional DDO-OFDM superchannel detection. With the proposed proof-of-concept architecture, we experimentally demonstrated a 116.7 Gb/s superchannel OFDM-PON system with transmission reach of 100 km, and 1:64 splitting ratio. We analyze the impact of carrier-to-sideband power ratio (CSPR) on system performance. The experiment result shows that, 5 dB power margin is still remained at ONU using such technique.

  6. Direct Detection of Erythromycin-Resistant Bordetella pertussis in Clinical Specimens by PCR.

    PubMed

    Wang, Zengguo; Han, Ruijun; Liu, Ying; Du, Quanli; Liu, Jifeng; Ma, Chaofeng; Li, Hengxin; He, Qiushui; Yan, Yongping

    2015-11-01

    Resistance of Bordetella pertussis to erythromycin has been increasingly reported. We developed an allele-specific PCR method for rapid detection of erythromycin-resistant B. pertussis directly from nasopharyngeal (NP) swab samples submitted for diagnostic PCR. Based on the proven association of erythromycin resistance with the A2047G mutation in the 23S rRNA of B. pertussis, four primers, two of which were designed to be specific for either the wild-type or the mutant allele, were used in two different versions of the allele-specific PCR assay. The methods were verified with results obtained by PCR-based sequencing of 16 recent B. pertussis isolates and 100 NP swab samples submitted for diagnostic PCR. The detection limits of the two PCR assays ranged from 10 to 100 fg per reaction for both erythromycin-susceptible and -resistant B. pertussis. Two amplified fragments of each PCR, of 286 and 112 bp, respectively, were obtained from a mutant allele of the isolates and/or NP swab samples containing B. pertussis DNAs. For the wild-type allele, only a 286-bp fragment was visible when the allele-specific PCR assay 1 was performed. No amplification was found when a number of non-Bordetella bacterial pathogens and NP swab samples that did not contain the DNAs of B. pertussis were examined. This assay can serve as an alternative for PCR-based sequencing, especially for local laboratories in resource-poor countries.

  7. Layered ACO-OFDM for intensity-modulated direct-detection optical wireless transmission.

    PubMed

    Wang, Qi; Qian, Chen; Guo, Xuhan; Wang, Zhaocheng; Cunningham, David G; White, Ian H

    2015-05-01

    Layered asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) with high spectral efficiency is proposed in this paper for optical wireless transmission employing intensity modulation with direct detection. In contrast to the conventional ACO-OFDM, which only utilizes odd subcarriers for modulation, leading to an obvious spectral efficiency loss, in layered ACO-OFDM, the subcarriers are divided into different layers and modulated by different kinds of ACO-OFDM, which are combined for simultaneous transmission. In this way, more subcarriers are used for data transmission and the spectral efficiency is improved. An iterative receiver is also proposed for layered ACO-OFDM, where the negative clipping distortion of each layer is subtracted once it is detected so that the signals from different layers can be recovered. Theoretical analysis shows that the proposed scheme can improve the spectral efficiency by up to 2 times compared with conventional ACO-OFDM approaches with the same modulation order. Meanwhile, simulation results confirm a considerable signal-to-noise ratio gain over ACO-OFDM at the same spectral efficiency. PMID:25969323

  8. How clean is clean: Non-destructive/direct methods of flux, residue detection

    SciTech Connect

    Welch, C.S.; Ray, U.; Stallard, B.R.; Watkins, R.D.; Koch, M.W.; Moya, M.M.

    1994-06-01

    The feasibility of three different non-destructive and direct methods of evaluating PCB (printed circuit boards) cleanliness was demonstrated. The detection limits associated with each method were established. In addition, the pros and cons of these methods as routine quality control inspection tools were discussed. OSEE (Optically Stimulated Electron Emission) was demonstrated to be a sensitive technique for detection of low levels of flux residues on insulating substances. However, future work including development of rugged OSEE instrumentation will determine whether the PCB industry can accept this technique in a production environment. FTIR (Fourier Transform Infrared) microscopy is a well established technique with well known characteristics. The inability of FTIR to discriminate an organic contaminant from an organic substrate limits its usefulness as a PCB line inspection tool, but it will still remain a technique for the QC/QA laboratory. One advantage of FTIR over the other two techniques described here is its ability to identify the chemical nature of the residue, which is important in Failure Mode Analysis. Optical imaging using sophisticated pattern recognition algorithms was found to be limited to high concentrations of residue. Further work on improved sensor techniques is necessary.

  9. Lenslet Array to Further Suppress Star Light for Direct Exoplanet Detection

    NASA Technical Reports Server (NTRS)

    Gong, Qian; McElwain, Michael; Shiri, Ron

    2016-01-01

    Direct imaging plays a key role in the detection and characterization of exoplanets orbiting within its host star's habitable zone. Many innovative ideas for starlight suppression and wavefront control have been proposed and developed over the past decade. However, several technological challenges still lie ahead to achieve the required contrast, including controlling the observatory pointing performance, fabricating occulting masks with tight optical tolerances, developing wavefront control algorithms, controlling stray light, advancing single photon detecting detectors, and integrated system-level issues. This paper explores how a lenslet array and pinhole mask may be implemented to further suppress uncorrected starlight that leaks through the occulting mask. An external occulter, or star shade, is simulated to demonstrate this concept, although this approach can be implemented for internal coronagraphs as well. We describe how to use simple relay optics to control the scene near the inner working angle and the level of the suppression expected. Furthermore, if the lenslet array is the input to an integral field spectrograph, as planned for the WFIRST mission, the spectral content of the exoplanet atmospheres can be obtained to determine if the observed planet is habitable and ultimately, if it is inhabited.

  10. Direct Imaging Detection of Methane in the Atmosphere of GJ 504 b

    NASA Technical Reports Server (NTRS)

    Janson, Markus; Brandt, Timothy; Kuzuhara, Masayuki; Spiegel, David; Thalmann, Christian; Currie, Thayne; Bonnefoy, Mickael; Zimmerman, Neil; Sorahana, Satoko; Kotani, Takayuki; Schlieder, Joshua; Hashimoto, Jun; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Abe, Lyu; Brandner, Wolfgang; Carson, Joseph; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Grady, Carol; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; McElwain, Michael

    2013-01-01

    Most exoplanets detected by direct imaging so far have been characterized by relatively hot (approximately greater than1000 K) and cloudy atmospheres. A surprising feature in some of their atmospheres has been a distinct lack of methane, possibly implying non-equilibrium chemistry. Recently, we reported the discovery of a planetary companion to the Sun-like star GJ 504 using Subaru/HiCIAO within the SEEDS survey. The planet is substantially colder (less than 600 K) than previously imaged planets, and has indications of fewer clouds, which implies that it represents a new class of planetary atmospheres with expected similarities to late T-type brown dwarfs in the same temperature range. If so, one might also expect the presence of significant methane absorption, which is characteristic of such objects. Here, we report the detection of deep methane absorption in the atmosphere of GJ 504 b, using the Spectral Differential Imaging mode of HiCIAO to distinguish the absorption feature around 1.6 micrometers. We also report updated JHK photometry based on new K(sub s)-band data and a re-analysis of the existing data. The results support the notion that GJ 504 b has atmospheric properties distinct from other imaged exoplanets, and will become a useful reference object for future planets in the same temperature range.

  11. 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.

  12. Direct Detection of Erythromycin-Resistant Bordetella pertussis in Clinical Specimens by PCR

    PubMed Central

    Wang, Zengguo; Han, Ruijun; Liu, Ying; Du, Quanli; Liu, Jifeng; Ma, Chaofeng; Li, Hengxin

    2015-01-01

    Resistance of Bordetella pertussis to erythromycin has been increasingly reported. We developed an allele-specific PCR method for rapid detection of erythromycin-resistant B. pertussis directly from nasopharyngeal (NP) swab samples submitted for diagnostic PCR. Based on the proven association of erythromycin resistance with the A2047G mutation in the 23S rRNA of B. pertussis, four primers, two of which were designed to be specific for either the wild-type or the mutant allele, were used in two different versions of the allele-specific PCR assay. The methods were verified with results obtained by PCR-based sequencing of 16 recent B. pertussis isolates and 100 NP swab samples submitted for diagnostic PCR. The detection limits of the two PCR assays ranged from 10 to 100 fg per reaction for both erythromycin-susceptible and -resistant B. pertussis. Two amplified fragments of each PCR, of 286 and 112 bp, respectively, were obtained from a mutant allele of the isolates and/or NP swab samples containing B. pertussis DNAs. For the wild-type allele, only a 286-bp fragment was visible when the allele-specific PCR assay 1 was performed. No amplification was found when a number of non-Bordetella bacterial pathogens and NP swab samples that did not contain the DNAs of B. pertussis were examined. This assay can serve as an alternative for PCR-based sequencing, especially for local laboratories in resource-poor countries. PMID:26224847

  13. DIRECT IMAGING DETECTION OF METHANE IN THE ATMOSPHERE OF GJ 504 b

    SciTech Connect

    Janson, Markus; Brandt, Timothy D.; Kuzuhara, Masayuki; Spiegel, David S.; Thalmann, Christian; Currie, Thayne; Bonnefoy, Mickaël; Zimmerman, Neil; Schlieder, Joshua; Brandner, Wolfgang; Feldt, Markus; Sorahana, Satoko; Kotani, Takayuki; Hashimoto, Jun; Kusakabe, Nobuhiko; Kudo, Tomoyuki; Egner, Sebastian; Abe, Lyu; Carson, Joseph C.; Goto, Miwa; and others

    2013-11-20

    Most exoplanets detected by direct imaging thus far have been characterized by relatively hot (≳1000 K) and cloudy atmospheres. A surprising feature in some of their atmospheres has been a distinct lack of methane, possibly implying non-equilibrium chemistry. Recently, we reported the discovery of a planetary companion to the Sun-like star GJ 504 using Subaru/HiCIAO within the Strategic Exploration of Exoplanets and Disks with Subaru survey. The planet is substantially colder (<600 K) than previously imaged planets, and has indications of fewer clouds, which implies that it represents a new class of planetary atmospheres with expected similarities to late T-type brown dwarfs in the same temperature range. If so, one might also expect the presence of significant methane absorption, which is characteristic of such objects. Here, we report the detection of deep methane absorption in the atmosphere of GJ 504 b, using the Spectral Differential Imaging mode of HiCIAO to distinguish the absorption features around 1.6 μm. We also report updated JHK photometry based on new K {sub s}-band data and a re-analysis of the existing data. The results support the notion that GJ 504 b has atmospheric properties distinct from other imaged exoplanets, and will become a useful reference object for future planets in the same temperature range.

  14. Bino variations: Effective field theory methods for dark matter direct detection

    NASA Astrophysics Data System (ADS)

    Berlin, Asher; Robertson, Denis S.; Solon, Mikhail P.; Zurek, Kathryn M.

    2016-05-01

    We apply effective field theory methods to compute bino-nucleon scattering, in the case where tree-level interactions are suppressed and the leading contribution is at loop order via heavy flavor squarks or sleptons. We find that leading log corrections to fixed-order calculations can increase the bino mass reach of direct detection experiments by a factor of 2 in some models. These effects are particularly large for the bino-sbottom coannihilation region, where bino dark matter as heavy as 5-10 TeV may be detected by near future experiments. For the case of stop- and selectron-loop mediated scattering, an experiment reaching the neutrino background will probe thermal binos as heavy as 500 and 300 GeV, respectively. We present three key examples that illustrate in detail the framework for determining weak scale coefficients, and for mapping onto a low-energy theory at hadronic scales, through a sequence of effective theories and renormalization group evolution. For the case of a squark degenerate with the bino, we extend the framework to include a squark degree of freedom at low energies using heavy particle effective theory, thus accounting for large logarithms through a "heavy-light current." Benchmark predictions for scattering cross sections are evaluated, including complete leading order matching onto quark and gluon operators, and a systematic treatment of perturbative and hadronic uncertainties.

  15. Direct sequencing of mitochondrial DNA detects highly divergent haplotypes in blue marlin (Makaira nigricans).

    PubMed

    Finnerty, J R; Block, B A

    1992-06-01

    We were able to differentiate between species of billfish (Istiophoridae family) and to detect considerable intraspecific variation in the blue marlin (Makaira nigricans) by directly sequencing a polymerase chain reaction (PCR)-amplified, 612-bp fragment of the mitochondrial cytochrome b gene. Thirteen variable nucleotide sites separated blue marlin (n = 26) into 7 genotypes. On average, these genotypes differed by 5.7 base substitutions. A smaller sample of swordfish from an equally broad geographic distribution displayed relatively little intraspecific variation, with an average of 1.3 substitutions separating different genotypes. A cladistic analysis of blue marlin cytochrome b variants indicates two major divergent evolutionary lines within the species. The frequencies of these two major evolutionary lines differ significantly between Atlantic and Pacific ocean basins. This finding is important given that the Atlantic stocks of blue marlin are considered endangered. Migration from the Pacific can help replenish the numbers of blue marlin in the Atlantic, but the loss of certain mitochondrial DNA haplotypes in the Atlantic due to overfishing probably could not be remedied by an influx of Pacific fish because of their absence in the Pacific population. Fishery management strategies should attempt to preserve the genetic diversity within the species. The detection of DNA sequence polymorphism indicates the utility of PCR technology in pelagic fishery genetics.

  16. Direct In Vivo Electrochemical Detection of Haemoglobin in Red Blood Cells

    NASA Astrophysics Data System (ADS)

    Toh, Rou Jun; Peng, Weng Kung; Han, Jongyoon; Pumera, Martin

    2014-08-01

    The electrochemical behavior of iron ion in haemoglobin provides insight to the chemical activity in the red blood cell which is important in the field of hematology. Herein, the detection of haemoglobin in human red blood cells on glassy carbon electrode (GC) was demonstrated. Red blood cells or raw blood cells was immobilized on a glassy carbon electrode surface with Nafion films employed to sandwich the layer of biological sample firmly on the electrode surface. Cyclic voltammetry (CV) analyses revealed a well-defined reduction peak for haemoglobin at about -0.30 V (vs. Ag/AgCl) at the red blood cell (GC-Nf-RBC-3Nf) and blood (GC-Nf-B-3Nf) film modified GCE in a pH 3.5 phosphate buffer solution. We further demonstrated that the complex biological conditions of a human red blood cell displayed no interference with the detection of haemoglobin. Such findings shall have an implication on the possibilities of studying the electrochemical behaviour of haemoglobin directly from human blood, for various scientific and clinical purposes.

  17. Direct Detection of C_2H_2 in Air and Human Breath by Cw-Crds

    NASA Astrophysics Data System (ADS)

    Schmidt, Florian M.; Vaittinen, Olavi; Metsälä, Markus; Halonen, Lauri

    2010-06-01

    Continuous wave cavity ring-down spectroscopy (cw-CRDS) is an established cavity-enhanced absorption technique that can provide the necessary sensitivity, selectivity and fast acquisition time for many applications involving the detection of trace species. We present a simple but highly sensitive cw-CRDS spectrometer based on an external cavity diode laser operating in the near-infrared region. This instrument allows us to directly detect acetylene (C_2H_2) mixing ratios in air with a detection limit of 120 parts per trillion by volume (pptv) measuring on a C_2H_2 absorption line at 6565.620 cm-1. Acetylene is a combustion product that is routinely used in environmental monitoring as a marker for anthropogenic emissions. In a recent work, the spectrometer was employed to measure the level of acetylene in indoor and outdoor air in Helsinki. Continuous flow measurements with high time resolution (one minute) revealed strong fluctuations in the acetylene mixing ratio in outdoor air during daytime. Due to its non-invasive nature and fast response time, the analysis of exhaled breath for medical diagnostics is an excellent and straightforward alternative to methods using urine or blood samples. In an ongoing study, the cw-CRDS instrument is used to establish the baseline level of acetylene in the breath of the healthy population. An elevated amount of acetylene in breath could indicate exposure to combustion exhausts or other volatile organic compound (VOC) rich sources. The latest results of this investigation will be presented. F. M. Schmidt, O. Vaittinen, M. Metsälä, P. Kraus and L. Halonen, submitted for publication in Appl. Phys. B.

  18. Direct biosensor detection of botulinum neurotoxin endopeptidase activity in sera from patients with type A botulism.

    PubMed

    Lévêque, Christian; Ferracci, Géraldine; Maulet, Yves; Mazuet, Christelle; Popoff, Michel; Seagar, Michael; El Far, Oussama

    2014-07-15

    Botulinum neurotoxin A (BoNT/A) has intrinsic endoprotease activity specific for SNAP-25, a key protein for presynaptic neurotransmitter release. The inactivation of SNAP-25 by BoNT/A underlies botulism, a rare but potentially fatal disease. There is a crucial need for a rapid and sensitive in vitro serological test for BoNT/A to replace the current in vivo mouse bioassay. Cleavage of SNAP-25 by BoNT/A generates neo-epitopes which can be detected by binding of a monoclonal antibody (mAb10F12) and thus measured by surface plasmon resonance (SPR). We have explored two SPR assay formats, with either mAb10F12 or His6-SNAP-25 coupled to the biosensor chip. When BoNT/A was incubated with SNAP-25 in solution and the reaction products were captured on a mAb-coated chip, a sensitivity of 5 fM (0.1LD50/ml serum) was obtained. However, this configuration required prior immunoprecipitation of BoNT/A. A sensitivity of 0.5 fM in 10% serum (0.1 LD50/ml serum) was attained when SNAP-25 was coupled directly to the chip, followed by sequential injection of BoNT/A samples and mAb10F12 into the flow system to achieve on-chip cleavage and detection, respectively. This latter format detected BoNT/A endoprotease activity in 50-100 µl serum samples from all patients (11/11) with type A botulism within 5h. No false positives occurred in sera from healthy subjects or patients with other neurological diseases. The automated chip-based procedure has excellent specificity and sensitivity, with significant advantages over the mouse bioassay in terms of rapidity, required sample volume and animal ethics.

  19. Optimisation of a direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores.

    PubMed

    Henczka, Marek; Djas, Małgorzata; Filipek, Katarzyna

    2013-01-01

    A direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores has been optimised. The results of the application of four types of growth media (BAT agar, YSG agar, K agar and SK agar) regarding the recovery and enumeration of A. acidoterrestris spores were compared. The influence of the type of applied growth medium, heat shock conditions, incubation temperature, incubation time, plating technique and the presence of apple juice in the sample on the accuracy of the detection and enumeration of A. acidoterrestris spores was investigated. Among the investigated media, YSG agar was the most sensitive medium, and its application resulted in the highest recovery of A. acidoterrestris spores, while K agar and BAT agar were the least suitable media. The effect of the heat shock time on the recovery of spores was negligible. When there was a low concentration of spores in a sample, the membrane filtration method was superior to the spread plating method. The obtained results show that heat shock carried out at 80°C for 10 min and plating samples in combination with membrane filtration on YSG agar, followed by incubation at 46°C for 3 days provided the optimal conditions for the detection and enumeration of A. acidoterrestris spores. Application of the presented method allows highly efficient, fast and sensitive identification and enumeration of A. acidoterrestris spores in food products. This methodology will be useful for the fruit juice industry for identifying products contaminated with A. acidoterrestris spores, and its practical application may prevent economic losses for manufacturers.

  20. RadSensor: Xray Detection by Direct Modulation of an Optical Probe Beam

    SciTech Connect

    Lowry, M E; Bennett, C V; Vernon, S P; Bond, T; Welty, R; Behymer, E; Petersen, H; Krey, A; Stewart, R; Kobayashi, N P; Sperry, V; Stephan, P; Reinhardt, C; Simpson, S; Stratton, P; Bionta, R; McKernan, M; Ables, E; Ott, L; Bond, S; Ayers, J.; Landen, O L; Bell, P M

    2003-08-01

    We present a new x-ray detection technique based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. The electron-hole pairs create a frequency dependent shift in optical refractive index and absorption. This is sensed by simultaneously directing an optical carrier beam through the same volume of semiconducting medium that has experienced an xray induced modulation in the electron-hole population. If the operating wavelength of the optical carrier beam is chosen to be close to the semiconductor band-edge, the optical carrier will be modulated significantly in phase and amplitude. This approach should be simultaneously capable of very high sensitivity and excellent temporal response, even in the difficult high-energy xray regime. At xray photon energies near 10 keV and higher, we believe that sub-picosecond temporal responses are possible with near single xray photon sensitivity. The approach also allows for the convenient and EMI robust transport of high-bandwidth information via fiber optics. Furthermore, the technology can be scaled to imaging applications. The basic physics of the detector, implementation considerations, and preliminary experimental data are presented and discussed.

  1. Evaluation of direct and buffy coat films of peripheral blood for the early detection of bacteraemia.

    PubMed

    Rodwell, R L; Leslie, A L; Tudehope, D I

    1989-04-01

    During an 8 month period, 298 evaluations of direct and buffy coat films of peripheral blood for the detection of bacteraemia were undertaken in 287 infants (243 less than 24 h of age and 55 aged between 2 days and 30 days). Bacteraemia was diagnosed by simultaneously drawn aerobic and anaerobic blood cultures. Intracellular organisms were observed in both the direct and buffy coat films of only four of 24 infants with bacteraemia, giving a sensitivity of 17%, specificity of 100% and positive and negative predictive values of 100% and 93%, respectively. Of 12 infants with bacteraemia on the first day of life, eight were asymptomatic when studied, and none of the 12 had positive smears. As two of four infants with positive smears died, it is concluded that in fulminating sepsis the tests seem to correlate with the degree of illness and may give useful information as to the causative organism and the choice of antibiotic. However, as a screening test, the present methodology lacks sensitivity and cost-effectiveness.

  2. Viscosity-density sensor with resonant torsional paddle for direct detection in liquid.

    PubMed

    Li, H; Wang, J; Li, X; Chen, D

    2011-12-01

    A novel micro-machined biosensor based on the resonant torsional paddle with electromagnetic excitation which can work in liquid directly is presented. The sensor designed consists of two paddles with resonant torsional mode, in which the energy loss of the resonator during the vibration is so lower that it can be suitable for detection in liquid. Finite element method analysis was carried out to guarantee the sensitivity of the sensor. Micro electro-mechanical system (MEMS) bulk silicon processes were adopted to accomplish the fabrication. A positive-feedback circuit with energy compensation is designed to improve the characteristics of the sensor in liquid. Experiments show that the resonant torsional paddle can work directly in liquid and the Q-factor of the sensor in liquid can be improved from 2.65 to 40 with energy compensation. Viscosity tests and density tests for the sensor show that the decrease in frequency and the decrease in Q-factor are related to density and viscosity of the solutions, respectively.

  3. Direct spectrophotometric detection of the endpoint in metachromatic titration of polydiallyldimethylammonium chloride in water

    NASA Astrophysics Data System (ADS)

    Gumbi, B.; Ngila, J. C.; Ndungu, P. G.

    Polydiallyldimethylammonium chloride (poly-DADMAC) is a water soluble polymer that easily ionizes when dissolved in water. This cationic polyelectrolyte is mainly used as a flocculant within the water treatment industry, but little is known of its toxicological properties or its fate in the environment. It is often assumed that the polyelectrolyte sorbs onto solid surfaces in the water treatment stream and may be removed with the sludge or by a sand bed filter; which may not always be the case. In any event, reliable analytical techniques are needed for the determination of poly-DADMAC in matrices of environmental relevance. Metachromatic polyelectrolyte titration was used to quantify poly-DADMAC in model and tap water samples. We compared a routine visual titration method with a direct spectrophotometric technique that uses a dip probe, spectrometer, and computer. The direct spectrophotometric technique allowed for the determination of titration curves at 634 nm and 510 nm, whereby the later value has never been successfully utilised in the literature. The method simplifies the data analysis, and our recovery and matrix interference experiments demonstrate that the method is accurate, precise, and robust. The detection limit for this method was 0.1 mg L-1 in model water and 0.5 mg L-1 in tap water. The limit of quantification for both water matrices was 0.5 mg L-1.

  4. Direct Detection of Protein Biomarkers in Human Fluids Using Site-Specific Antibody Immobilization Strategies

    PubMed Central

    Soler, Maria; Estevez, M.-Carmen; Alvarez, Mar; Otte, Marinus A.; Sepulveda, Borja; Lechuga, Laura M.

    2014-01-01

    Design of an optimal surface biofunctionalization still remains an important challenge for the application of biosensors in clinical practice and therapeutic follow-up. Optical biosensors offer real-time monitoring and highly sensitive label-free analysis, along with great potential to be transferred to portable devices. When applied in direct immunoassays, their analytical features depend strongly on the antibody immobilization strategy. A strategy for correct immobilization of antibodies based on the use of ProLinker™ has been evaluated and optimized in terms of sensitivity, selectivity, stability and reproducibility. Special effort has been focused on avoiding antibody manipulation, preventing nonspecific adsorption and obtaining a robust biosurface with regeneration capabilities. ProLinker™-based approach has demonstrated to fulfill those crucial requirements and, in combination with PEG-derivative compounds, has shown encouraging results for direct detection in biological fluids, such as pure urine or diluted serum. Furthermore, we have implemented the ProLinker™ strategy to a novel nanoplasmonic-based biosensor resulting in promising advantages for its application in clinical and biomedical diagnosis. PMID:24481229

  5. Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection

    NASA Astrophysics Data System (ADS)

    Patterson, N.; Adams, D. P.; Hodges, V. C.; Vasile, M. J.; Michael, J. R.; Kotula, P. G.

    2008-06-01

    We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si3N4 and W/Si3N4 to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations.

  6. Controlled fabrication of nanopores using a direct focused ion beam approach with back face particle detection.

    PubMed

    Patterson, N; Adams, D P; Hodges, V C; Vasile, M J; Michael, J R; Kotula, P G

    2008-06-11

    We report a direct, ion drilling technique that enables the reproducible fabrication and placement of nanopores in membranes of different thickness. Using a 30 keV focused Ga ion beam column combined with an in situ, back face, multi-channelplate particle detector, nanopores are sputtered in Si(3)N(4) and W/Si(3)N(4) to have diameters as small as 12 nm. Transmission electron microscopy shows that focused ion beam-drilled holes are near-conical with the diameter decreasing from entry to exit side. By monitoring the detector signal during ion exposure, the drilled hole width can be minimized such that the exit-side diameter is smaller than the full width at half-maximum of the nominally Gaussian-shaped incident beam. Judicious choice of the beam defining aperture combined with back face particle detection allows for reproducible exit-side hole diameters between 18 and 100 nm. The nanopore direct drilling technique does not require potentially damaging broad area exposure to tailor hole sizes. Moreover, this technique successfully achieves breakthrough despite the effects of varying membrane thickness, redeposition, polycrystalline grain structure, and slight ion beam current fluctuations. PMID:21825787

  7. Drug Detection and Quantification Directly from Tissue using Novel Ionization Methods for Mass Spectrometry

    PubMed Central

    Wang, Beixi; Dearring, Chenelle L.; Wager-Miller, James; Mackie, Ken; Trimpin, Sarah

    2016-01-01

    Solvent assisted ionization inlet (SAII) and matrix assisted ionization vacuum (MAIV) were used to rapidly quantify an antipsychotic drug, clozapine, directly from surfaces with minimal sample preparation. This simple surface analysis method based on SAII- and MAIV-mass spectrometry (MS) was developed to allow detection of endogenous lipids, metabolites, and clozapine directly from mouse brain tissue sections. Rapid surface assessment was achieved by SAII with the assistance of heat on the mass spectrometer inlet, and MAIV showed capability on heat-limited instruments with better reproducibility. In addition, isotope dilution and standard addition were used without sample clean-up, and the results correlate well to liquid chromatography (LC)-tandem MS with sample work-up. Using the simple surface methods, standard solutions containing clozapine and deuterated sample (clozapine-d8) at different concentration ratios were used to extract and quantify clozapine from brain tissue sections of drug-treated mouse at different thicknesses. The amount of clozapine extracted by these surface methods was independent of tissue thickness. PMID:26307700

  8. A Mode Detection Method Using the Azimuthal Directivity of a Turbofan Model

    NASA Technical Reports Server (NTRS)

    Thomas, R. H.; Farassat, F.; Clark, L. R.; Gerhold, C. H.; Kelly, J. J.; Becker, L. E.

    1999-01-01

    The azimuthal, far field directivity of a scale fan model was measured in high resolution. The model is a 12 inch diameter rotor with 16 blades followed by 40 stator vanes. The tests were conducted at the nominal 100% speed corresponding to a tip speed of 905 ft/sec. Measurement of the radiated sound field, forward of the fan, was made in an anechoic chamber with an inflow control device and a baffle separating the aft and forward radiated interaction noise. The acoustic field was surveyed with a circular hoop array of 16 microphones which was moved to 14 axial stations. At each axial station the hoop was rotated in half-degree increments to take 736 points in the azimuthal angle. In addition to sound pressure level, the phase angle relative to a reference microphone was measured at each point. The sound pressure level is shown to vary in patterns by 10-15 dB especially for the fundamental tone but also for the first and second harmonic. A far field mode detection method has been developed and used with the data which determines the modes generated by the fan and which then interact to form the azimuthal directivity.

  9. Detection of Baking Soda in Flat Bread by Direct pH Metery and Alkalinity Measurement

    NASA Astrophysics Data System (ADS)

    Jahed Khaniki, G. H. R.; Vaezi, F.; Yunesian, M.; Nabizadeh, R.; Paseban, G. H. A.

    The objective of this study is evaluation of direct pH metery and alkalinity measurement methods for determination of baking soda in lavash bread (a kind of flat bread) in order to introduce and recommend a good practice of control. For running the experiments, various samples of lavash bread having different concentrations of baking soda were prepared. Ten grams of each sample were mixed with distilled water and then the prepared solutions were filtrated. The filtrates were then analyzed for pH and total alkalinity according to the distractions described in Standard Methods. Results show a significant correlation between the pH values of bread samples and the amount of baking soda. Also, a positive correlation has been observed between the alkalinity of bread samples and used baking soda. By comparing the R2-values specified for these two methods it could be concluded that the direct pH metery method is more reasonable. Furthermore, by this simple method it is possible to accelerate the detection of minute amounts of this chemical in bread.

  10. High-resolution imaging of a single atom for direct detection of atomic motion

    NASA Astrophysics Data System (ADS)

    Wong-Campos, Jaime; Johnson, Kale; Neyenhuis, Brian; Mizrahi, Jonathan; Monroe, Christopher; Monroe lab Team

    2015-05-01

    We present the high-resolution detection of the motion of a single trapped 171Yb+ ion using high quality imaging optical elements. Light scattered from a trapped ion is collected in a lens system with 0.6 input numerical aperture and working distance of 11.5 mm. Near diffraction-limited performance from the imaging system is verified through the use of a Zernike expansion over the point spread function, giving a minimum spot size (FWHM) of 375 nm. By means of a position sensitive detector, we measure a photon shot-noise limited sensitivity on the position of the trapped ion to be ~ 5 nm/sqrt(Hz), bottoming out to an minimum absolute sensitivity of ~ 1 nm. We use this technique perform to directly measure the rf-induced micromotion of the trapped ion, and this technique can also be used to directly sense the thermal or driven secular motion of the trapped ion. This work is supported by the NSF Physics Frontier Center at JQI.

  11. Do Experts and Novices Direct Attention Differently in Examining Physics Diagrams? A Study of Change Detection Using the Flicker Technique

    ERIC Educational Resources Information Center

    Morphew, Jason W.; Mestre, Jose P.; Ross, Brian H.; Strand, Natalie E.

    2015-01-01

    It is known that experts identify or perceive meaningful patterns in visual stimuli related to their domain of expertise. This study explores the speed with which experts and novices detect changes in physics diagrams. Since change detection depends on where individuals direct their attention, differences in the speed with which experts and…

  12. Bacteroides fragilis in biopsies of patients with major abscesses and diabetic foot infections: direct molecular versus culture-based detection.

    PubMed

    Stappers, Mark H T; Hagen, Ferry; Reimnitz, Peter; Mouton, Johan W; Meis, Jacques F; Gyssens, Inge C

    2016-06-01

    Direct determination by pathogen-specific real-time PCR assay for Bacteroides fragilis was compared to culture in major abscess and diabetic foot infection biopsy samples. Real-time PCR resulted in an increased detection rate of 12% for B. fragilis and could improve the detection of B. fragilis in clinical samples. PMID:27112830

  13. Development of a modular directional and spectral neutron detection system using solid-state detectors

    NASA Astrophysics Data System (ADS)

    Weltz, A.; Torres, B.; McElwain, L.; Dahal, R.; Huang, J.; Bhat, I.; Lu, J.; Danon, Y.

    2015-08-01

    A detection system using room-temperature, microstructured solid-state thermal neutron detectors with very low leakage current has been developed at Rensselaer Polytechnic Institute (RPI) with the ability to provide positional and spectral information about an unknown neutron source. The Directional and Spectral Neutron Detection System (DSNDS) utilizes a set of small-but-scalable, zero-bias solid-state thermal neutron detectors which have demonstrated high thermal neutron efficiency and adequate gamma insensitivity. The DSNDS can gather spectral information about an unknown neutron source with a relatively small number of detectors, simplifying the detector electronics and minimizing cost; however, the DSNDS is modular in design, providing the capability to increase the detection efficiency and angular resolution. The system used in this paper was comprised of a stack of five high-density polyethylene (HDPE) disks with a thickness of 5 cm and a diameter of 30 cm, the middle disk containing 16 detectors positioned as one internal (moderated) and one external (unmoderated) ring of solid-state neutron detectors. These two detector rings provide the ability to determine the directionality of a neutron source. The system gathers spectral information about a neutron source in two ways: by measuring the relative responses of the internal ring of detectors as well as measuring the ratio of the internal-to-external detector responses. Experiments were performed with variable neutron spectra: a 252Cf spontaneous fission neutron source which was HDPE moderated, HDPE reflected, lead (Pb) shielded, and bare in order to benchmark the system for spectral sensitivity. Simulations were performed in order to characterize the neutron spectra corresponding to each of the source configurations and showed agreement with experimental measurements. The DSNDS demonstrates the ability to determine the relative angle of the source and the hardness of the neutron spectrum. By using the

  14. Erratum: Erratum to: Physics from solar neutrinos in dark matter direct detection experiments

    NASA Astrophysics Data System (ADS)

    Cerdeño, David G.; Fairbairn, Malcolm; Jubb, Thomas; Machado, Pedro A. N.; Vincent, Aaron C.; Bœhm, Céline

    2016-09-01

    We correct 1) missing factors of 2 in cross section expressions in table 4 of the published article; and 2) the LUX bound in figure 6 on the B-L coupling from 2015 data, which displayed erroneously strong constraints due to a computer error. Conclusions remain unchanged.

  15. Direct gas-phase detection of nerve and blister warfare agents utilizing active capillary plasma ionization mass spectrometry.

    PubMed

    Wolf, J-C; Schaer, M; P Siegenthaler, P; Zenobi, R

    2015-01-01

    Ultrasensitive direct gas-phase detection of chemical warfare agents (CWAs) is demonstrated utilizing active capillary plasma ionization and triple quadrupole mass spectrometry (MS) instrumentation. Four G- agents, two V-agents and various blistering agents [including sulfur mustard (HD)] were detected directly in the gas phase with limits of detection in the low parts per trillion (ng m(-3)) range. The direct detection of HD was shown for dry carrier gas conditions, but signals vanished when humidity was present, indicating a possible direct detection of HD after sufficient gas phase pretreatment. The method provided sufficient sensitivity to monitor directly the investigated volatile CWAs way below their corresponding minimal effect dose, and in most cases even below the eight hours worker exposure concentration. In general, the ionization is very soft, with little to no in-source fragmentation. Especially for the G-agents, some dimer formation occurred at higher concentrations. This adds complexity, but also further selectivity, to the corresponding mass spectra. Our results show that the active capillary plasma ionization is a robust, sensitive, "plug and play" ambient ionization source suited (but not exclusively) to the very sensitive detection of CWAs. It has the potential to be used with portable MS instrumentation. PMID:26307710

  16. High resolution biomedical imaging system with direct detection of x-rays via a charge coupled device

    DOEpatents

    Atac, M.; McKay, T.A.

    1998-04-21

    An imaging system is provided for direct detection of x-rays from an irradiated biological tissue. The imaging system includes an energy source for emitting x-rays toward the biological tissue and a charge coupled device (CCD) located immediately adjacent the biological tissue and arranged transverse to the direction of irradiation along which the x-rays travel. The CCD directly receives and detects the x-rays after passing through the biological tissue. The CCD is divided into a matrix of cells, each of which individually stores a count of x-rays directly detected by the cell. The imaging system further includes a pattern generator electrically coupled to the CCD for reading a count from each cell. A display device is provided for displaying an image representative of the count read by the pattern generator from the cells of the CCD. 13 figs.

  17. High resolution biomedical imaging system with direct detection of x-rays via a charge coupled device

    DOEpatents

    Atac, Muzaffer; McKay, Timothy A.

    1998-01-01

    An imaging system is provided for direct detection of x-rays from an irradiated biological tissue. The imaging system includes an energy source for emitting x-rays toward the biological tissue and a charge coupled device (CCD) located immediately adjacent the biological tissue and arranged transverse to the direction of irradiation along which the x-rays travel. The CCD directly receives and detects the x-rays after passing through the biological tissue. The CCD is divided into a matrix of cells, each of which individually stores a count of x-rays directly detected by the cell. The imaging system further includes a pattern generator electrically coupled to the CCD for reading a count from each cell. A display device is provided for displaying an image representative of the count read by the pattern generator from the cells of the CCD.

  18. A direct measurement of the forward shock speed in supernova remnant ``0519‑69.0'': Constraints on the age, ambient density and electron-ion temperature equilibration

    NASA Astrophysics Data System (ADS)

    Hovey, Luke; Hughes, John P.; Eriksen, Kristoffer; Pandya, Viraj

    2016-06-01

    The supernova remnant 0519-69.0 is the second youngest Ia remnant in the Large Magellanic Cloud. The typing of the remnant rests primarily on ejecta abundances inferred from X-ray spectra and the Balmer-dominated nature of its forward shock. Using two narrow-band Hα imaging with the Hubble Space Telescope separated by ~1 year we are able to measure the global shock velocity of the remnant to be 2780 km/s. Using the global shock speed with the measured size of the remnant as constraints we employ one-dimensional hydrodynamic simulations to constrain the age and ambient medium density of the remnant. We also report on the degree of electron-to-ion temperature ratios for select portions of the rim for which we have spectroscopic measurements using the Robert Stobie Spectrograph on the Southern African Large Telescope.

  19. Goal-Directed Modulation of Neural Memory Patterns: Implications for fMRI-Based Memory Detection.

    PubMed

    Uncapher, Melina R; Boyd-Meredith, J Tyler; Chow, Tiffany E; Rissman, Jesse; Wagner, Anthony D

    2015-06-01

    Remembering a past event elicits distributed neural patterns that can be distinguished from patterns elicited when encountering novel information. These differing patterns can be decoded with relatively high diagnostic accuracy for individual memories using multivoxel pattern analysis (MVPA) of fMRI data. Brain-based memory detection--if valid and reliable--would have clear utility beyond the domain of cognitive neuroscience, in the realm of law, marketing, and beyond. However, a significant boundary condition on memory decoding validity may be the deployment of "countermeasures": strategies used to mask memory signals. Here we tested the vulnerability of fMRI-based memory detection to countermeasures, using a paradigm that bears resemblance to eyewitness identification. Participants were scanned while performing two tasks on previously studied and novel faces: (1) a standard recognition memory task; and (2) a task wherein they attempted to conceal their true memory state. Univariate analyses revealed that participants were able to strategically modulate neural responses, averaged across trials, in regions implicated in memory retrieval, including the hippocampus and angular gyrus. Moreover, regions associated with goal-directed shifts of attention and thought substitution supported memory concealment, and those associated with memory generation supported novelty concealment. Critically, whereas MVPA enabled reliable classification of memory states when participants reported memory truthfully, the ability to decode memory on individual trials was compromised, even reversing, during attempts to conceal memory. Together, these findings demonstrate that strategic goal states can be deployed to mask memory-related neural patterns and foil memory decoding technology, placing a significant boundary condition on their real-world utility. PMID:26041920

  20. Direct-detection EPID dosimetry: investigation of a potential clinical configuration for IMRT verification

    NASA Astrophysics Data System (ADS)

    Vial, Philip; Gustafsson, Helen; Oliver, Lyn; Baldock, Clive; Greer, Peter B.

    2009-12-01

    The routine use of electronic portal imaging devices (EPIDs) as dosimeters for radiotherapy quality assurance is complicated by the non-water equivalence of the EPID's dose response. A commercial EPID modified to a direct-detection configuration was previously demonstrated to provide water-equivalent dose response with dmax solid water build-up and 10 cm solid water backscatter. Clinical implementation of the direct EPID (dEPID) requires a design that maintains the water-equivalent dose response, can be incorporated onto existing EPID support arms and maintains sufficient image quality for clinical imaging. This study investigated the dEPID dose response with different configurations of build-up and backscatter using varying thickness of solid water and copper. Field size output factors and beam profiles measured with the dEPID were compared with ionization chamber measurements of dose in water for both 6 MV and 18 MV. The dEPID configured with dmax solid water build-up and no backscatter (except for the support arm) was within 1.5% of dose in water data for both energies. The dEPID was maintained in this configuration for clinical dosimetry and image quality studies. Close agreement between the dEPID and treatment planning system was obtained for an IMRT field with 98.4% of pixels within the field meeting a gamma criterion of 3% and 3 mm. The reduced sensitivity of the dEPID resulted in a poorer image quality based on quantitative (contrast-to-noise ratio) and qualitative (anthropomorphic phantom) studies. However, clinically useful images were obtained with the dEPID using typical treatment field doses. The dEPID is a water-equivalent dosimeter that can be implemented with minimal modifications to the standard commercial EPID design. The proposed dEPID design greatly simplifies the verification of IMRT dose delivery.

  1. Transit dosimetry in IMRT with an a-Si EPID in direct detection configuration

    NASA Astrophysics Data System (ADS)

    Sabet, Mahsheed; Rowshanfarzad, Pejman; Vial, Philip; Menk, Frederick W.; Greer, Peter B.

    2012-08-01

    In this study an amorphous silicon electronic portal imaging device (a-Si EPID) converted to direct detection configuration was investigated as a transit dosimeter for intensity modulated radiation therapy (IMRT). After calibration to dose and correction for a background offset signal, the EPID-measured absolute IMRT transit doses for 29 fields were compared to a MatriXX two-dimensional array of ionization chambers (as reference) using Gamma evaluation (3%, 3 mm). The MatriXX was first evaluated as reference for transit dosimetry. The accuracy of EPID measurements was also investigated by comparison of point dose measurements by an ionization chamber on the central axis with slab and anthropomorphic phantoms in a range of simple to complex fields. The uncertainty in ionization chamber measurements in IMRT fields was also investigated by its displacement from the central axis and comparison with the central axis measurements. Comparison of the absolute doses measured by the EPID and MatriXX with slab phantoms in IMRT fields showed that on average 96.4% and 97.5% of points had a Gamma index<1 in head and neck and prostate fields, respectively. For absolute dose comparisons with anthropomorphic phantoms, the values changed to an average of 93.6%, 93.7% and 94.4% of points with Gamma index<1 in head and neck, brain and prostate fields, respectively. Point doses measured by the EPID and ionization chamber were within 3% difference for all conditions. The deviations introduced in the response of the ionization chamber in IMRT fields were<1%. The direct EPID performance for transit dosimetry showed that it has the potential to perform accurate, efficient and comprehensive in vivo dosimetry for IMRT.

  2. Direct-detection EPID dosimetry: investigation of a potential clinical configuration for IMRT verification.

    PubMed

    Vial, Philip; Gustafsson, Helen; Oliver, Lyn; Baldock, Clive; Greer, Peter B

    2009-12-01

    The routine use of electronic portal imaging devices (EPIDs) as dosimeters for radiotherapy quality assurance is complicated by the non-water equivalence of the EPID's dose response. A commercial EPID modified to a direct-detection configuration was previously demonstrated to provide water-equivalent dose response with d(max) solid water build-up and 10 cm solid water backscatter. Clinical implementation of the direct EPID (dEPID) requires a design that maintains the water-equivalent dose response, can be incorporated onto existing EPID support arms and maintains sufficient image quality for clinical imaging. This study investigated the dEPID dose response with different configurations of build-up and backscatter using varying thickness of solid water and copper. Field size output factors and beam profiles measured with the dEPID were compared with ionization chamber measurements of dose in water for both 6 MV and 18 MV. The dEPID configured with d(max) solid water build-up and no backscatter (except for the support arm) was within 1.5% of dose in water data for both energies. The dEPID was maintained in this configuration for clinical dosimetry and image quality studies. Close agreement between the dEPID and treatment planning system was obtained for an IMRT field with 98.4% of pixels within the field meeting a gamma criterion of 3% and 3 mm. The reduced sensitivity of the dEPID resulted in a poorer image quality based on quantitative (contrast-to-noise ratio) and qualitative (anthropomorphic phantom) studies. However, clinically useful images were obtained with the dEPID using typical treatment field doses. The dEPID is a water-equivalent dosimeter that can be implemented with minimal modifications to the standard commercial EPID design. The proposed dEPID design greatly simplifies the verification of IMRT dose delivery. PMID:19904032

  3. Detection of inhomogeneities in precipitation time series in Portugal using direct sequential simulation

    NASA Astrophysics Data System (ADS)

    Ribeiro, Sara; Caineta, Júlio; Costa, Ana Cristina; Henriques, Roberto; Soares, Amílcar

    2016-05-01

    Climate data homogenisation is of major importance in climate change monitoring, validation of weather forecasting, general circulation and regional atmospheric models, modelling of erosion, drought monitoring, among other studies of hydrological and environmental impacts. The reason is that non-climate factors can cause time series discontinuities which may hide the true climatic signal and patterns, thus potentially bias the conclusions of those studies. In the last two decades, many methods have been developed to identify and remove these inhomogeneities. One of those is based on a geostatistical simulation technique (DSS - direct sequential simulation), where local probability density functions (pdfs) are calculated at candidate monitoring stations using spatial and temporal neighbouring observations, which then are used for the detection of inhomogeneities. Such approach has been previously applied to detect inhomogeneities in four precipitation series (wet day count) from a network with 66 monitoring stations located in the southern region of Portugal (1980-2001). That study revealed promising results and the potential advantages of geostatistical techniques for inhomogeneity detection in climate time series. This work extends the case study presented before and investigates the application of the geostatistical stochastic approach to ten precipitation series that were previously classified as inhomogeneous by one of six absolute homogeneity tests (Mann-Kendall, Wald-Wolfowitz runs, Von Neumann ratio, Pettitt, Buishand range test, and standard normal homogeneity test (SNHT) for a single break). Moreover, a sensitivity analysis is performed to investigate the number of simulated realisations which should be used to infer the local pdfs with more accuracy. Accordingly, the number of simulations per iteration was increased from 50 to 500, which resulted in a more representative local pdf. As in the previous study, the results are compared with those from the

  4. Inhomogeneities detection in annual precipitation time series in Portugal using direct sequential simulation

    NASA Astrophysics Data System (ADS)

    Caineta, Júlio; Ribeiro, Sara; Costa, Ana Cristina; Henriques, Roberto; Soares, Amílcar

    2014-05-01

    Climate data homogenisation is of major importance in monitoring climate change, the validation of weather forecasting, general circulation and regional atmospheric models, modelling of erosion, drought monitoring, among other studies of hydrological and environmental impacts. This happens because non-climate factors can cause time series discontinuities which may hide the true climatic signal and patterns, thus potentially bias the conclusions of those studies. In the last two decades, many methods have been developed to identify and remove these inhomogeneities. One of those is based on geostatistical simulation (DSS - direct sequential simulation), where local probability density functions (pdf) are calculated at candidate monitoring stations, using spatial and temporal neighbouring observations, and then are used for detection of inhomogeneities. This approach has been previously applied to detect inhomogeneities in four precipitation series (wet day count) from a network with 66 monitoring stations located in the southern region of Portugal (1980-2001). This study revealed promising results and the potential advantages of geostatistical techniques for inhomogeneities detection in climate time series. This work extends the case study presented before and investigates the application of the geostatistical stochastic approach to ten precipitation series that were previously classified as inhomogeneous by one of six absolute homogeneity tests (Mann-Kendall test, Wald-Wolfowitz runs test, Von Neumann ratio test, Standard normal homogeneity test (SNHT) for a single break, Pettit test, and Buishand range test). Moreover, a sensibility analysis is implemented to investigate the number of simulated realisations that should be used to accurately infer the local pdfs. Accordingly, the number of simulations per iteration is increased from 50 to 500, which resulted in a more representative local pdf. A set of default and recommended settings is provided, which will help

  5. Source coherence impairments in a direct detection direct sequence optical code-division multiple-access system.

    PubMed

    Fsaifes, Ihsan; Lepers, Catherine; Lourdiane, Mounia; Gallion, Philippe; Beugin, Vincent; Guignard, Philippe

    2007-02-01

    We demonstrate that direct sequence optical code- division multiple-access (DS-OCDMA) encoders and decoders using sampled fiber Bragg gratings (S-FBGs) behave as multipath interferometers. In that case, chip pulses of the prime sequence codes generated by spreading in time-coherent data pulses can result from multiple reflections in the interferometers that can superimpose within a chip time duration. We show that the autocorrelation function has to be considered as the sum of complex amplitudes of the combined chip as the laser source coherence time is much greater than the integration time of the photodetector. To reduce the sensitivity of the DS-OCDMA system to the coherence time of the laser source, we analyze the use of sparse and nonperiodic quadratic congruence and extended quadratic congruence codes.

  6. Performance Evaluation and Optimization of Receivers for Direct Detection Optical Communication.

    NASA Astrophysics Data System (ADS)

    Schumacher, Klaus

    Available from UMI in association with The British Library. This thesis is concerned with performance evaluation and optimization of direct detection optical communication systems. It is based on a comprehensive model of a fibre -optic receiver which accounts for the stochastic nature of the signals in a mathematically rigorous manner. Special emphasis is placed on the inclusion of jitter into the receiver description since this impairment is of increasing importance in very high speed communication systems. A tight upper bound on the error probability, the modified Chernoff bound, is employed for performance assessment. Its formulation incorporates timing imperfections either of the received signal or of the extracted clock. A distribution-free bound is derived which is based on jitter range and variance only. Using variational calculus techniques receiver filters are identified which minimize the bound on the error probability, taking into account simultaneously all impairments including jitter and arbitrarily coloured additive noise. The optimum filter impulse responses are obtained as solutions of a differential equation. This approach does not address the problem of filter realizability. However, realizable, low-order filters can be obtained--again on the basis of the modified Chernoff bound --by means of numerical optimization. This approach is particularly attractive because it results in considerable performance advantages over conventionally used filters of the same complexity. The performance of these practical filters is further found to be only marginally inferior to that of the theoretical optimum filter.

  7. Direct detection of nasal Staphylococcus aureus carriage via helicase-dependent isothermal amplification and chip hybridization

    PubMed Central

    2012-01-01

    Background The bacterium Staphylococcus aureus constitutes one of the most important causes of nosocomial infections. One out of every three individuals naturally carries S. aureus in their anterior nares, and nasal carriage is associated with a significantly higher infection rate in hospital settings. Nasal carriage can be either persistent or intermittent, and it is the persistent carriers who, as a group, are at the highest risk of infection and who have the highest nasal S. aureus cell counts. Prophylactic decolonization of S. aureus from patients’ noses is known to reduce the incidence of postsurgical infections, and there is a clear rationale for rapid identification of nasal S. aureus carriers among hospital patients. Findings A molecular diagnostic assay was developed which is based on helicase-dependent target amplification and amplicon detection by chip hybridization to a chip surface, producing a visible readout. Nasal swabs from 70 subjects were used to compare the molecular assay against culturing on “CHROMagar Staph aureus” agar plates. The overall relative sensitivity was 89%, and the relative specificity was 94%. The sensitivity rose to 100% when excluding low-count subjects (<100 S. aureus colony-forming units per swab). Conclusions This molecular assay is much faster than direct culture and has sensitivity that is appropriate for identification of high-count (>100 S. aureus colony-forming units per swab) nasal S. aureus carriers who are at greatest risk for nosocomial infections. PMID:22882800

  8. Direct detection signatures of self-interacting dark matter with a light mediator

    SciTech Connect

    Nobile, Eugenio Del; Kaplinghat, Manoj; Yu, Hai-Bo E-mail: mkapling@uci.edu

    2015-10-01

    Self-interacting dark matter (SIDM) is a simple and well-motivated scenario that could explain long-standing puzzles in structure formation on small scales. If the required self-interaction arises through a light mediator (with mass ∼ 10 MeV) in the dark sector, this new particle must be unstable to avoid overclosing the universe. The decay of the light mediator could happen due to a weak coupling of the hidden and visible sectors, providing new signatures for direct detection experiments. The SIDM nuclear recoil spectrum is more peaked towards low energies compared to the usual case of contact interactions, because the mediator mass is comparable to the momentum transfer of nuclear recoils. We show that the SIDM signal could be distinguished from that of DM particles with contact interactions by considering the time-average energy spectrum in experiments employing different target materials, or the average and modulated spectra in a single experiment. Using current limits from LUX and SuperCDMS, we also derive strong bounds on the mixing parameter between hidden and visible sector.

  9. What is the probability that direct detection experiments have observed dark matter?

    SciTech Connect

    Bozorgnia, Nassim; Schwetz, Thomas E-mail: schwetz@fysik.su.se

    2014-12-01

    In Dark Matter direct detection we are facing the situation of some experiments reporting positive signals which are in conflict with limits from other experiments. Such conclusions are subject to large uncertainties introduced by the poorly known local Dark Matter distribution. We present a method to calculate an upper bound on the joint probability of obtaining the outcome of two potentially conflicting experiments under the assumption that the Dark Matter hypothesis is correct, but completely independent of assumptions about the Dark Matter distribution. In this way we can quantify the compatibility of two experiments in an astrophysics independent way. We illustrate our method by testing the compatibility of the hints reported by DAMA and CDMS-Si with the limits from the LUX and SuperCDMS experiments. The method does not require Monte Carlo simulations but is mostly based on using Poisson statistics. In order to deal with signals of few events we introduce the so-called ''signal length'' to take into account energy information. The signal length method provides a simple way to calculate the probability to obtain a given experimental outcome under a specified Dark Matter and background hypothesis.

  10. Directly detected 55Mn MRI: Application to phantoms for human hyperpolarized 13C MRI development

    PubMed Central

    von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D.; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B.

    2014-01-01

    In this work we demonstrate for the first time directly detected manganese-55 (55Mn) MRI using a clinical 3T MRI scanner designed for human hyperpolarized 13C clinical studies with no additional hardware modifications. Due to the similar frequency of the 55Mn and 13C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective “13C” MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, 55Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical 13C phantom MRI, at greatly reduced cost as compared with large 13C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d= 8 cm) containing concentrated aqueous sodium permanganate (2.7M) was scanned rapidly by 55Mn MRI in a human head coil tuned for 13C, using a balanced SSFP acquisition. The requisite penetration of RF magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for 55Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image SNR of ~60 at 0.5cm3 spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP 13C coils and methods designed for human studies. PMID:25179135

  11. Direct detection signatures of self-interacting dark matter with a light mediator

    SciTech Connect

    Nobile, Eugenio Del; Kaplinghat, Manoj; Yu, Hai-Bo

    2015-10-27

    Self-interacting dark matter (SIDM) is a simple and well-motivated scenario that could explain long-standing puzzles in structure formation on small scales. If the required self-interaction arises through a light mediator (with mass ∼10 MeV) in the dark sector, this new particle must be unstable to avoid overclosing the universe. The decay of the light mediator could happen due to a weak coupling of the hidden and visible sectors, providing new signatures for direct detection experiments. The SIDM nuclear recoil spectrum is more peaked towards low energies compared to the usual case of contact interactions, because the mediator mass is comparable to the momentum transfer of nuclear recoils. We show that the SIDM signal could be distinguished from that of DM particles with contact interactions by considering the time-average energy spectrum in experiments employing different target materials, or the average and modulated spectra in a single experiment. Using current limits from LUX and SuperCDMS, we also derive strong bounds on the mixing parameter between hidden and visible sector.

  12. Unified explanation for dark matter and electroweak baryogenesis with direct detection and gravitational wave signatures

    NASA Astrophysics Data System (ADS)

    Chala, Mikael; Nardini, Germano; Sobolev, Ivan

    2016-09-01

    A minimal extension of the Standard Model that provides both a dark matter candidate and a strong first-order electroweak phase transition (EWPT) consists of two additional Lorentz and gauge singlets. In this paper we work out a composite Higgs version of this scenario, based on the coset S O (7 )/S O (6 ). We show that by embedding the elementary fermions in appropriate representations of S O (7 ), all dominant interactions are described by only three free effective parameters. Within the model dependencies of the embedding, the theory predicts one of the singlets to be stable and responsible for the observed dark matter abundance. At the same time, the second singlet introduces new C P -violation phases and triggers a strong first-order EWPT, making electroweak baryogenesis feasible. It turns out that this scenario does not conflict with current observations and it is promising for solving the dark matter and baryon asymmetry puzzles. The tight predictions of the model will be accessible at the forthcoming dark matter direct detection and gravitational wave experiments.

  13. A powerful weighted statistic for detecting group differences of directed biological networks

    PubMed Central

    Yuan, Zhongshang; Ji, Jiadong; Zhang, Xiaoshuai; Xu, Jing; Ma, Daoxin; Xue, Fuzhong

    2016-01-01

    Complex disease is largely determined by a number of biomolecules interwoven into networks, rather than a single biomolecule. Different physiological conditions such as cases and controls may manifest as different networks. Statistical comparison between biological networks can provide not only new insight into the disease mechanism but statistical guidance for drug development. However, the methods developed in previous studies are inadequate to capture the changes in both the nodes and edges, and often ignore the network structure. In this study, we present a powerful weighted statistical test for group differences of directed biological networks, which is independent of the network attributes and can capture the changes in both the nodes and edges, as well as simultaneously accounting for the network structure through putting more weights on the difference of nodes locating on relatively more important position. Simulation studies illustrate that this method had better performance than previous ones under various sample sizes and network structures. One application to GWAS of leprosy successfully identifies the specific gene interaction network contributing to leprosy. Another real data analysis significantly identifies a new biological network, which is related to acute myeloid leukemia. One potential network responsible for lung cancer has also been significantly detected. The source R code is available on our website. PMID:27686331

  14. Alignment of direct detection device micrographs using a robust Optical Flow approach.

    PubMed

    Abrishami, Vahid; Vargas, Javier; Li, Xueming; Cheng, Yifan; Marabini, Roberto; Sorzano, Carlos Óscar Sánchez; Carazo, José María

    2015-03-01

    The introduction of direct detection devices in cryo-EM has shown that specimens present beam-induced motion (BIM). Consequently, in this work, we develop a BIM correction method at the image level, resulting in an integrated image in which the in-plane BIM blurring is compensated prior to particle picking. The methodology is based on a robust Optical Flow (OF) approach that can efficiently correct for local movements in a rapid manner. The OF works particularly well if the BIM pattern presents a substantial degree of local movements, which occurs in our data sets for Falcon II data. However, for those cases in which the BIM pattern corresponds to global movements, we have found it advantageous to first run a global motion correction approach and to subsequently apply OF. Additionally, spatial analysis of the Optical Flow allows for quantitative analysis of the BIM pattern. The software that incorporates the new approach is available in XMIPP (http://xmipp.cnb.csic.es).

  15. Initial evaluation of a direct detection device detector for single particle cryo-electron microscopy.

    PubMed

    Milazzo, Anna-Clare; Cheng, Anchi; Moeller, Arne; Lyumkis, Dmitry; Jacovetty, Erica; Polukas, James; Ellisman, Mark H; Xuong, Nguyen-Huu; Carragher, Bridget; Potter, Clinton S

    2011-12-01

    We report on initial results of using a new direct detection device (DDD) for single particle reconstruction of vitreous ice embedded specimens. Images were acquired on a Tecnai F20 at 200keV and a nominal magnification of 29,000×. This camera has a significantly improved signal to noise ratio and modulation transfer function (MTF) at 200keV compared to a standard CCD camera installed on the same microscope. Control of the DDD has been integrated into Leginon, an automated data collection system. Using GroEL as a test specimen, we obtained images of ∼30K particles with the CCD and the DDD from the same specimen sample using essentially identical imaging conditions. Comparison of the maps reconstructed from the CCD images and the DDD images demonstrates the improved performance of the DDD. We also obtained a 3D reconstruction from ∼70K GroEL particles acquired using the DDD; the quality of the density map demonstrates the potential of this new recording device for cryoEM data acquisition.

  16. Direct detection of light “Ge-phobic” exothermic dark matter

    SciTech Connect

    Gelmini, Graciela B.; Georgescu, Andreea; Huh, Ji-Haeng

    2014-07-15

    We present comparisons of direct dark matter (DM) detection data for light WIMPs with exothermic scattering with nuclei (exoDM), both assuming the Standard Halo Model (SHM) and in a halo model — independent manner. Exothermic interactions favor light targets, thus reducing the importance of upper limits derived from xenon targets, the most restrictive of which is at present the LUX limit. In our SHM analysis the CDMS-II-Si and CoGeNT regions become allowed by these bounds, however the recent SuperCDMS limit rejects both regions for exoDM with isospin-conserving couplings. An isospin-violating coupling of the exoDM, in particular one with a neutron to proton coupling ratio of −0.8 (which we call “Ge-phobic”), maximally reduces the DM coupling to germanium and allows the CDMS-II-Si region to become compatible with all bounds. This is also clearly shown in our halo-independent analysis.

  17. Direct Measurement of Trace Elemental Mercury in Hydrocarbon Matrices by Gas Chromatography with Ultraviolet Photometric Detection.

    PubMed

    Gras, Ronda; Luong, Jim; Shellie, Robert A

    2015-11-17

    We introduce a technique for the direct measurement of elemental mercury in light hydrocarbons such as natural gas. We determined elemental mercury at the parts-per-trillion level with high precision [<3% RSD (n = 20 manual injection)] using gas chromatography with ultraviolet photometric detection (GC-UV) at 254 nm. Our approach requires a small sample volume (1 mL) and does not rely on any form of sample preconcentration. The GC-UV separation employs an inert divinylbenzene porous layer open tubular column set to separate mercury from other components in the sample matrix. We incorporated a 10-port gas-sampling valve in the GC-UV system, which enables automated sampling, as well as back flushing capability to enhance system cleanliness and sample throughput. Total analysis time is <2 min, and the procedure is linear over a range of 2-83 μg/m(3) [correlation coefficient of R(2) = 0.998] with a measured recovery of >98% over this range.

  18. Direct detection of singlet oxygen generated by UVA irradiation in human cells and skin.

    PubMed

    Baier, Jürgen; Maisch, Tim; Maier, Max; Landthaler, Michael; Bäumler, Wolfgang

    2007-06-01

    UVA light produces deleterious biological effects in which singlet oxygen plays a major role. These effects comprise a significant risk of carcinogenesis in the skin and cataract formation of the eye lens. Singlet oxygen is generated by UVA light absorption in endogenous molecules present in the cells. To elucidate the primary processes and sources of singlet oxygen in tissue, it is a major goal to uncover the hidden process of singlet oxygen generation, in particular in living tissue. When exposing keratinocytes or human skin in vivo to UVA laser light (355 nm) at 6 J/cm2, we measured the luminescence of singlet oxygen at 1,270 nm. This is a positive and direct proof of singlet oxygen generation in cells and skin by UVA light. Moreover, a clear signal of singlet oxygen luminescence was detected in phosphatidylcholine suspensions (water or ethanol) irradiated by UVA. Oxidized products of phosphatidylcholine are the likely chromophores because phosphatidylcholine itself does not absorb at 355 nm. The signal intensity was reduced by mannitol or super oxide dismutase. Additionally, the monochromatic UVA irradiation at 355 nm leads to upregulation of the key cytokine IL-12. This affects the balance of UV radiation on the immune system, which is comparable to effects of broadband UVA irradiation. PMID:17363921

  19. Spectrally efficient direct-detected OFDM transmission employing an iterative estimation and cancellation technique.

    PubMed

    Peng, Wei-Ren; Wu, Xiaoxia; Feng, Kai-Ming; Arbab, Vahid R; Shamee, Bishara; Yang, Jeng-Yuan; Christen, Louis C; Willner, Alan E; Chi, Sien

    2009-05-25

    We demonstrate a linearly field-modulated, direct-detected virtual SSB-OFDM (VSSB-OFDM) transmission with an RF tone placed at the edge of the signal band. By employing the iterative estimation and cancellation technique for the signal-signal beat interference (SSBI) at the receiver, our approach alleviates the need of the frequency gap, which is typically reserved for isolating the SSBI, and saves half the electrical bandwidth, thus being very spectrally efficient. We derive the theoretical model for the VSSB-OFDM system and detail the signal processing for the iterative approach conducted at the receiver. Possible limitations for this iterative approach are also given and discussed. We successfully transmit a 10 Gbps, 4-quadrature-amplitude-modulation (QAM) VSSB-OFDM signal through 340 km of uncompensated standard single mode fiber (SSMF) with almost no penalty. In addition, the simulated results show that the proposed scheme has an approximately 2 dB optical-signal-to-noise-ratio (OSNR) gain and has a better chromatic dispersion (CD) tolerance compared with the previous intensity-modulated SSB-OFDM system.

  20. Rapid analytical procedure for neomycin determination in ointments by CE with direct UV detection.

    PubMed

    Huidobro, A L; García, A; Barbas, C

    2009-07-12

    The purpose of this study was the development of an analytical methodology for the determination of neomycin in a complex pharmaceutical preparation. The simplified methodology consisted of a primary liquid-liquid extraction, employing a mixture of chloroform and water (1.25:1, v/v) and subsequent analysis by CE applying a capillary zone electrophoresis method with a 30 cm (effective length), 50 microm (internal diameter) polyacrylamide-coated silica capillary. The background electrolyte consisted of 35 mM phosphate and 15 mM acetate buffer set at pH 4.7, under normal polarity mode and direct UV detection at 200 nm. The separation of the target analyte from the complex matrix was accomplished in less than 3 min. The analytical method was successfully validated in order to verify its proper selectivity, linearity, accuracy and precision for the goal intended and its further implementation for the quantification of the active compound in the pharmaceutical speciality for quality control.