Average fractional polarization of extragalactic sources at Planck frequencies

Recent detailed simulations have shown that an insufficiently accurate characterization of the contamination of unresolved polarized extragalactic sources can seriously bias measurements of the primordial cosmic microwave background (CMB) power spectrum if the tensor-to-scalar ratio r ∼ 0.001, as predicted by models currently of special interest (e.g., Starobinsky’s R2 and Higgs inflation). This has motivated a reanalysis of the median polarization fraction of extragalactic sources (radio-loud AGNs and dusty galaxies) using data from the Planck polarization maps. Our approach, exploiting the intensity distribution analysis, mitigates or overcomes the most delicate aspects of earlier analyses based on stacking techniques. By means of simulations, we have shown that the residual noise bias on the median polarization fraction, Πmedian, of extragalactic sources is generally ≲0.1%. For radio sources, we have found Πmedian ≃ 2.83%, with no significant dependence on either frequency or flux density, in good agreement with the earlier estimate and with high-sensitivity measurements in the frequency range 5–40 GHz. No polarization signal is detected in the case of dusty galaxies, implying 90% confidence upper limits of Πdusty ≲ 2.2% at 353 GHz and of ≲3.9% at 217 GHz. The contamination of CMB polarization maps by unresolved point sources is discussed.

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Fluctuations in the Microwave Sky

Symposium - International Astronomical Union ◽

10.1017/s0074180900109933 ◽

1996 ◽

Vol 168 ◽

pp. 59-70

Author(s):

R. B. Partridge

Keyword(s):

Radio Emission ◽

Large Array ◽

Microwave Background ◽

Very Large Array ◽

Cosmic Background ◽

Upper Limits ◽

Great Progress ◽

Sunyaev Zel'dovich Effect ◽

Made In

This paper reviews the great progress recently made in searches for and the characterization of anisotropies in the cosmic microwave background. We now have secure detections on some angular scales and improved upper limits on others. As the sensitivity of such searches increases, understanding sources of foreground noise (e.g., Galactic and extragalactic radio emission) becomes more important. Also reviewed are the contributions aperture synthesis (interferometric) observations can make in characterizing cosmic background fluctuations and foreground sources of noise. Some recent results from the Very Large Array at λ = 3.6 cm are given; these set a limit δT/T ≲ 1.4 × 10−5on fluctuations at θ ~ 80′. Recent work on the Sunyaev-Zel'dovich effect is summarized.

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Ultrastructural identification of three types of sensory setae on copepod antennae

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141159 ◽

1995 ◽

Vol 53 ◽

pp. 956-957

Author(s):

T. M. Weatherby ◽

P.H. Lenz

Keyword(s):

Phase Locking ◽

Membrane Surface ◽

Reaction Times ◽

High Sensitivity ◽

Structural Features ◽

Calanoid Copepods ◽

Marine Food Webs ◽

Dendritic Membrane ◽

Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

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Complex Permittivity Characterization of Liquid Samples Based on a Split Ring Resonator (SRR)

Sensors ◽

10.3390/s21103385 ◽

2021 ◽

Vol 21 (10) ◽

pp. 3385

Author(s):

Jialu Ma ◽

Jingchao Tang ◽

Kaicheng Wang ◽

Lianghao Guo ◽

Yubin Gong ◽

...

Keyword(s):

Resonant Frequency ◽

Complex Permittivity ◽

Ring Resonator ◽

High Sensitivity ◽

Split Ring Resonator ◽

Debye Model ◽

Split Ring ◽

Liquid Samples ◽

Microwave Sensor

A complex permittivity characterization method for liquid samples has been proposed. The measurement is carried out based on a self-designed microwave sensor with a split ring resonator (SRR), the unload resonant frequency of which is 5.05 GHz. The liquid samples in capillary are placed in the resonant zone of the fabricated senor for high sensitivity measurement. The frequency shift of 58.7 MHz is achieved when the capillary is filled with ethanol, corresponding a sensitivity of 97.46 MHz/μL. The complex permittivity of methanol, ethanol, isopropanol (IPA) and deionized water at the resonant frequency are measured and calibrated by the first order Debye model. Then, the complex permittivity of different concentrations of aqueous solutions of these materials are measured by using the calibrated sensor system. The results show that the proposed sensor has high sensitivity and accuracy in measuring the complex permittivity of liquid samples with volumes as small as 0.13 μL. It provides a useful reference for the complex permittivity characterization of small amount of liquid chemical samples. In addition, the characterization of an important biological sample (inositol) is carried out by using the proposed sensor.

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Characterization of volcanic thermal anomalies by means of sub-pixel temperature distribution analysis

Bulletin of Volcanology ◽

10.1007/s00445-005-0037-2 ◽

2005 ◽

Vol 68 (7-8) ◽

pp. 641-651 ◽

Cited By ~ 12

Author(s):

Valerio Lombardo ◽

Maria Fabrizia Buongiorno ◽

Stefania Amici

Keyword(s):

Temperature Distribution ◽

Distribution Analysis ◽

Thermal Anomalies

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Reconstruction of the activity of point sources for the accurate characterization of nuclear waste drums by segmented gamma scanning

Applied Radiation and Isotopes ◽

10.1016/j.apradiso.2011.02.009 ◽

2011 ◽

Vol 69 (6) ◽

pp. 880-889 ◽

Cited By ~ 13

Author(s):

Thomas Krings ◽

Eric Mauerhofer

Keyword(s):

Nuclear Waste ◽

Point Sources ◽

Waste Drums ◽

Gamma Scanning

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Statistical characterization of cosmic microwave background temperature patterns in anisotropic cosmologies

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2010.17922.x ◽

2011 ◽

Vol 412 (1) ◽

pp. 492-502 ◽

Cited By ~ 7

Author(s):

Rockhee Sung ◽

Jo Short ◽

Peter Coles

Keyword(s):

Cosmic Microwave Background ◽

Microwave Background ◽

Statistical Characterization ◽

Cosmic Microwave Background Temperature ◽

Background Temperature

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Characterization of Piezoelectric Nanofiber Composites Acoustic Emission Sensor for Structure Health Monitoring

Volume 5: 6th International Conference on Micro- and Nanosystems; 17th Design for Manufacturing and the Life Cycle Conference ◽

10.1115/detc2012-71538 ◽

2012 ◽

Cited By ~ 1

Author(s):

Xi Chen ◽

Yong Shi

Keyword(s):

Acoustic Emission ◽

Lead Zirconate Titanate ◽

High Sensitivity ◽

Lead Zirconate ◽

Steel Bar ◽

Promising Application ◽

Soft Polymer ◽

Active Fiber Composites ◽

The Mathematical Model

A nanoscale active fiber composites (NAFCs) based acoustic emission (AE) sensor with high sensitivity is developed. The lead zirconate titanate (PZT) nanofibers, with the diameter of approximately 80 nm, were electrospun on a silicon substrate. Nanofibers were parallel aligned on the substrate under a controlled electric field. The interdigitated electrodes were deposited on the PZT nanofibers and packaged by spinning a thin soft polymer layer on the top of the sensor. The hysteresis loop shows a typical ferroelectric property of as-spun PZT nanofibers. The mathematical model of the voltage generation when the elastic waves were reaching the sensor was studied. The sensor was tested by mounting on a steel surface and the measured output voltage under the periodic impact of a grounded steel bar was over 35 mV. The small size of the developed PZT NAFCs AE sensor shows a promising application in monitoring the structures by integration into composites.

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Electrophysiological characterization and computational models of HVC neurons in the zebra finch

Journal of Neurophysiology ◽

10.1152/jn.00162.2013 ◽

2013 ◽

Vol 110 (5) ◽

pp. 1227-1245 ◽

Cited By ~ 20

Author(s):

Arij Daou ◽

Matthew T. Ross ◽

Frank Johnson ◽

Richard L. Hyson ◽

Richard Bertram

Keyword(s):

Computational Models ◽

Premotor Cortex ◽

Brain Slices ◽

Ionic Currents ◽

Proper Name ◽

Using Data ◽

Electrophysiological Characterization

The nucleus HVC (proper name) within the avian analog of mammal premotor cortex produces stereotyped instructions through the motor pathway leading to precise, learned vocalization by songbirds. Electrophysiological characterization of component HVC neurons is an important requirement in building a model to understand HVC function. The HVC contains three neural populations: neurons that project to the RA (robust nucleus of arcopallium), neurons that project to Area X (of the avian basal ganglia), and interneurons. These three populations are interconnected with specific patterns of excitatory and inhibitory connectivity, and they fire with characteristic patterns both in vivo and in vitro. We performed whole cell current-clamp recordings on HVC neurons within brain slices to examine their intrinsic firing properties and determine which ionic currents are responsible for their characteristic firing patterns. We also developed conductance-based models for the different neurons and calibrated the models using data from our brain slice work. These models were then used to generate predictions about the makeup of the ionic currents that are responsible for the different responses to stimuli. These predictions were then tested and verified in the slice using pharmacological manipulations. The model and the slice work highlight roles of a hyperpolarization-activated inward current ( Ih), a low-threshold T-type Ca2+ current ( ICa-T), an A-type K+ current ( IA), a Ca2+-activated K+ current ( ISK), and a Na+-dependent K+ current ( IKNa) in driving the characteristic neural patterns observed in the three HVC neuronal populations. The result is an improved characterization of the HVC neurons responsible for song production in the songbird.

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