7,086 research outputs found

    ELVIS - ELectromagnetic Vector Information Sensor

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    The ELVIS instrument was recently proposed by the authors for the Indian Chandrayaan-1 mission to the Moon and is presently under consideration by the Indian Space Research Organisation (ISRO). The scientific objective of ELVIS is to explore the electromagnetic environment of the moon. ELVIS samples the full three-dimensional (3D) electric field vector, E(x,t), up to 18 MHz, with selective Nyqvist frequency bandwidths down to 5 kHz, and one component of the magnetic field vector, B(x,t), from a few Hz up to 100 kHz.As a transient detector, ELVIS is capable of detecting pulses with a minimum pulse width of 5 ns. The instrument comprises three orthogonal electric dipole antennas, one magnetic search coil antenna and a four-channel digital sampling system, utilising flexible digital down conversion and filtering together with state-of-the-art onboard digital signal processing.Comment: 8 pages, 3 figures. Submitted to the DGLR Int. Symposium "To Moon and Beyond", Bremen, Germany, 2005. Companion paper to arXiv:astro-ph/050921

    Activation of NF- B protein prevents the transition from juvenile ovary to testis and promotes ovarian development in Zebrafish

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    Testis differentiation in zebrafish involves juvenile ovary to testis transformation initiated by an apoptotic wave. The molecular regulation of this transformation process is not fully understood. NF-κB is activated at an early stage of development and has been shown to interact with steroidogenic factor-1 in mammals, leading to the suppression of anti-Müllerian hormone (Amh) gene expression. Because steroidogenic factor-1 and Amh are important for proper testis development, NF-κB-mediated induction of anti-apoptotic genes could, therefore, also play a role in zebrafish gonad differentiation. The aim of this study was to examine the potential role of NF-κB in zebrafish gonad differentiation. Exposure of juvenile zebrafish to heat-killed Escherichia coli activated the NF-κB pathways and resulted in an increased ratio of females from 30 to 85%. Microarray and quantitative real-time-PCR analysis of gonads showed elevated expression of NF-κB-regulated genes. To confirm the involvement of NF-κB-induced anti-apoptotic effects, zebrafish were treated with sodium deoxycholate, a known inducer of NF-κB or NF-κB activation inhibitor (NAI). Sodium deoxycholate treatment mimicked the effect of heat-killed bacteria and resulted in an increased proportion of females from 25 to 45%, whereas the inhibition of NF-κB using NAI resulted in a decrease in females from 45 to 20%. This study provides proof for an essential role of NF-κB in gonadal differentiation of zebrafish and represents an important step toward the complete understanding of the complicated process of sex differentiation in this species and possibly other cyprinid teleosts as well

    Statistical properties of ionospheric stimulated electromagnetic emissions

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    We have analysed the statistical properties of the stimulated electromagnetic emissions (SEE) spectral features in the steady state, reached after a long period of continuous HF pumping of the ionosphere in experiments performed at the Sura ionospheric radio research facility in Russia. Using a digital filter bank method, we have been able to analyse complex valued signals within narrow frequency bands. Each of the SEE spectral features are thereby separated into a number of narrow spectral components. Statistical tests were performed for all these spectral components and the distributions of the spectral amplitudes and phases were evaluated. Also, a test for sinusoidal components was performed. These tests showed that all observed SEE features were indistinguishable from coloured Gaussian noise. The test results exclude that the SEE features can be the result of a single isolated coherent process, but does not rule out that there could be many statistically independent parametric wave-wave processes taking place simultaneously at various parts of the HF-pumped ionosphere, as long as the superposition from all these is incoherent. Furthermore, from the test results, we cannot exclude the possibility that the waveforms of some, or all, of the SEE features may be chaotic

    A measurement of the differential cross section for the two-body photodisintegration of 3He at theta_LAB = 90deg using tagged photons in the energy range 14 -- 31 MeV

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    The two-body photodisintegration of 3He has been investigated using tagged photons with energies from 14 -- 31 MeV at MAX-lab in Lund, Sweden. The two-body breakup channel was unambiguously identified by the (nonsimultaneous) detection of both protons and deuterons. This approach was made feasible by the over-determined kinematic situation afforded by the tagged-photon technique. Proton- and deuteron-energy spectra were measured using four silicon surface-barrier detector telescopes located at a laboratory angle of 90deg with respect to the incident photon-beam direction. Average statistical and systematic uncertainties of 5.7% and 6.6% in the differential cross section were obtained for 11 photon-energy bins with an average width of 1.2 MeV. The results are compared to previous experimental data measured at comparable photon energies as well as to the results of two recent Faddeev calculations which employ realistic potential models and take into account three-nucleon forces and final-state interactions. Both the accuracy and precision of the present data are improved over the previous measurements. The data are in good agreement with most of the previous results, and favor the inclusion of three-nucleon forces in the calculations.Comment: 12 pages, 13 figures; further Referee comments addresse

    A Quantum solution to the Byzantine agreement problem

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    We present a solution to an old and timely problem in distributed computing. Like Quantum Key Distribution (QKD), quantum channels make it possible to achieve taks classically impossible. However, unlike QKD, here the goal is not secrecy but agreement, and the adversary is not outside but inside the game, and the resources require qutrits.Comment: 4 pages, 1 figur

    The association of maternal-fetal attachment with smoking and smoking cessation during pregnancy in The FinnBrain Birth Cohort Study

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    BackgroundSmoking in pregnancy constitutes a preventable risk factor for fetal/child development and maternal-fetal attachment (MFA) seems to contain a momentum that can break the chain of adverse outcomes by promoting maternal prenatal health practices. This study aimed to explore the association of MFA with smoking at any time during pregnancy and smoking cessation in early pregnancy, and the modifying role of MFA on the expected effects of education and prenatal psychological distress (PPD) on prenatal smoking behavior.MethodsThe pregnant women (n=3766) participated in the The FinnBrain Birth Cohort Study in Finland between December 2011 and April 2015. The binary outcomes, smoking at any time during pregnancy and smoking cessation in early pregnancy, were obtained from self-reports at gestational weeks (gwks) 14 and 34 and The Finnish Medical Birth Register. MFA was assessed with the Maternal-Fetal Attachment Scale (MFAS) at gwks 24 and 34. Logistic regression analyses were used to determine the association between MFA and maternal prenatal smoking behavior.FindingsThe prevalence of smoking was 16.5%, and 58.1% of the smokers quit smoking during pregnancy. The independent associations of total MFA scores with prenatal smoking behavior were not established (aOR=1.00-1.02, multiplicity adjusted p>0.05). A higher score in the altruistic subscale of MFA, Giving of self, associated with a higher probability of smoking cessation (24 gwks: aOR=1.13, 95% CI [1.04, 1.24], p=0.007, multiplicity adjusted p=0.062; 34 gwks: aOR=1.17, 95% CI [1.07, 1.29], p<0.001, multiplicity adjusted p=0.008). The modifying effect of MFA on the observed associations between PPD and smoking in pregnancy and between maternal education and smoking in pregnancy / smoking cessation in early pregnancy was not demonstrated. ConclusionsThe altruistic dimension of maternal-fetal attachment associates with an increased probability of smoking cessation during pregnancy and therefore strengthening altruistic maternal-fetal attachment may constitute a promising novel approach for interventions aiming at promoting smoking cessation during pregnancy

    The Distribution of Redshifts in New Samples of Quasi-stellar Objects

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    Two new samples of QSOs have been constructed from recent surveys to test the hypothesis that the redshift distribution of bright QSOs is periodic in log(1+z)\log(1+z). The first of these comprises 57 different redshifts among all known close pairs or multiple QSOs, with image separations \leq 10\arcsec, and the second consists of 39 QSOs selected through their X-ray emission and their proximity to bright comparatively nearby active galaxies. The redshift distributions of the samples are found to exhibit distinct peaks with a periodic separation of 0.089\sim 0.089 in log(1+z)\log(1+z) identical to that claimed in earlier samples but now extended out to higher redshift peaks z=2.63,3.45z = 2.63, 3.45 and 4.47, predicted by the formula but never seen before. The periodicity is also seen in a third sample, the 78 QSOs of the 3C and 3CR catalogues. It is present in these three datasets at an overall significance level 10510^{-5} - 10610^{-6}, and appears not to be explicable by spectroscopic or similar selection effects. Possible interpretations are briefly discussed.Comment: submitted for publication in the Astronomical Journal, 15 figure

    Exciton enhanced dye sensitized solar cells

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    Date du colloque&nbsp;: 05/2009</p

    L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCam

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    We present the first observations obtained with the L'-band AGPM vortex coronagraph recently installed on LBTI/LMIRCam. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from diamond subwavelength gratings. It is designed to improve the sensitivity and dynamic range of high-resolution imaging at very small inner working angles, down to 0.09 arcseconds in the case of LBTI/LMIRCam in the L' band. During the first hours on sky, we observed the young A5V star HR\,8799 with the goal to demonstrate the AGPM performance and assess its relevance for the ongoing LBTI planet survey (LEECH). Preliminary analyses of the data reveal the four known planets clearly at high SNR and provide unprecedented sensitivity limits in the inner planetary system (down to the diffraction limit of 0.09 arcseconds).Comment: 9 pages, 4 figures, SPIE proceeding
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