Intensive Spectroscopic Monitoring of NGC 5548 with HST and IUE

We present preliminary results on a combined HST/IUE/ground-based monitoring campaign on the Seyfert 1 galaxy NGC 5548 undertaken by the International AGN Watch in order to answer questions that require both high temporal resolution (one day) and high signal-to-noise ratios. Our preliminary conclusions are (1) the ultraviolet and optical continuum variations are simultaneous to within a day (2) the He II λ1640 variations lag behind the continuum by about 1.7 days, and (3) the velocity field of the C IV-emitting region is not characterized by bulk by radial motion, but the higher velocity gas seems to originate closer to the continuum source than the lower velocity gas.

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Spectropolarimetry of Type IIn SN2010jl: Peering Into the Heart of a Monster

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312013178 ◽

2011 ◽

Vol 7 (S279) ◽

pp. 325-326 ◽

Cited By ~ 1

Author(s):

Franz E. Bauer ◽

Paula Zelaya ◽

Alejandro Clocchiatti ◽

Justyn Maund

Keyword(s):

High Signal ◽

Signal To Noise ◽

Polarization Signal ◽

Noise Data ◽

The Continuum ◽

Complex Origin

AbstractWe report results for two epochs of spectropolarimetry on the luminous type IIn SN2010jl, taken at ≈36 and 85 days post-explosion with VLT FORS2-PMOS. The high signal-to-noise data demonstrate distinct evolution in the continuum and the broad lines point to a complex origin for the various emission components and to a potentially common polarization signal for the type IIn class even over 1-2 orders of magnitude in luminosity output.

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Optical measurement of the corneal oscillation for the determination of the intraocular pressure

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2018-0093 ◽

2019 ◽

Vol 64 (4) ◽

pp. 471-480 ◽

Cited By ~ 3

Author(s):

Jan Osmers ◽

Michael Sorg ◽

Andreas Fischer

Keyword(s):

Intraocular Pressure ◽

Optical Measurement ◽

Signal To Noise Ratio ◽

Significant Risk ◽

High Signal ◽

High Temporal Resolution ◽

Signal To Noise ◽

Handheld Device ◽

Noise Ratio ◽

Reference Sensor

Abstract Motivation Glaucoma is currently the most common irreversible cause of blindness worldwide. A significant risk factor is an individually increased intraocular pressure (IOP). A precise measurement method is needed to determine the IOP in order to support the diagnosis of the disease and to monitor the outcome of the IOP reduction as a medical intervention. A handheld device is under development with which the patient can perform self-measurements outside the clinical environment. Method For the measurement principle of the self-tonometer the eye is acoustically excited to oscillate, which is analyzed and attributed to the present IOP. In order to detect the corneal oscillation, an optical sensor is required which meets the demands of a compact, battery driven self-tonometer. A combination of an infrared diode and a phototransistor provides a high-resolution measurement of the corneal oscillation in the range of 10 μm–150 μm, which is compared to a reference sensor in the context of this study. By means of an angular arrangement of the emitter and the detector, the degree of reflected radiation of the cornea can be increased, allowing a measurement with a high signal-to-noise ratio. Results By adjusting the angle of incidence between the detector and the emitter, the signal-to-noise ratio was improved by 40 dB which now allows reasonable measurements of the corneal oscillation. For low amplitudes (10 μm) the signal-to-noise ratio is 10% higher than that of the commercial reference sensor. On the basis of amplitude variations at different IOP levels, the estimated standard uncertainty amounts to <0.5 mm Hg in the physiological pressure range with the proposed measuring approach. Conclusion With a compact and cost-effective approach, that suits the requirements for a handheld self-tonometer, the corneal oscillation can be detected with high temporal resolution. The cross-sensitivity of the sensor concept concerning a distance variation can be reduced by adding a distance sensor. Existing systematic influences of corneal biomechanics will be integrated in the sensor concept as a consecutive step.

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Broad Line Variations in NGC 5548

Symposium - International Astronomical Union ◽

10.1017/s0074180900140549 ◽

1989 ◽

Vol 134 ◽

pp. 114-115

Author(s):

Edward I. Rosenblatt ◽

Matthew A. Malkan

Keyword(s):

Monitoring Program ◽

Seyfert Galaxies ◽

Active Galaxies ◽

Broad Line ◽

Line Flux ◽

Continuum Source ◽

Line Region ◽

Profile Changes ◽

Ngc 5548 ◽

The Continuum

Since broad line variations can, in principle, constrain the structure and kinematics of the broad line region in active galaxies we have conducted a monitoring program of 20 Seyfert galaxies over a 5 year period in order to study broad line flux and profile changes. Included in our sample is the Seyfert 1.5 galaxy NGC 5548. Fifteen observations were taken from 1979 to 1984 mainly with the 60″ Palomar telescope and a SIT vidicon spectrograph. Measurements show (Fig. 1) that both the Hβ and Hγ line flux varied by 200% and the continuum varied by 300%. Furthermore, these changes were positively correlated as one would expect from photoionization by a central continuum source.

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Properties of flares and CMEs on EV Lac: possible erupting filament

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3152 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5047-5058

Author(s):

Priscilla Muheki ◽

E W Guenther ◽

T Mutabazi ◽

E Jurua

Keyword(s):

Impulsive Phase ◽

Continuum Source ◽

Spectroscopic Monitoring ◽

Energetic Radiation ◽

Long Time ◽

Balmer Lines ◽

M Stars ◽

Ev Lac ◽

Short Time ◽

The Continuum

ABSTRACT Flares and coronal mass ejections (CMEs) are very powerful events in which energetic radiation and particles are ejected within a short time. These events thus can strongly affect planets that orbit these stars. This is particularly relevant for planets of M-stars, because these stars stay active for a long time during their evolution and yet potentially habitable planets orbit at short distance. Unfortunately, not much is known about the relation between flares and CMEs in M-stars as only very few CMEs have so far been observed in M-stars. In order to learn more about flares and CMEs on M-stars, we monitored the active M-star EV Lac spectroscopically at high resolution. We find 27 flares with energies between 1.6 × 1031 and 1.4 × 1032 erg in $\rm H\alpha$ during 127 h of spectroscopic monitoring and 49 flares with energies between 6.3 × 1031 and 1.1 × 1033 erg during the 457 h of Transiting Exoplanet Survey Satellite (TESS) observation. Statistical analysis shows that the ratio of the continuum flux in the TESS band to the energy emitted in $\rm H\alpha$ is 10.408 ± 0.026. Analysis of the spectra shows an increase in the flux of the He ii 4686 Å line during the impulsive phase of some flares. In three large flares, we detect a continuum source with a temperature between 6900 and 23 000 K. In none of the flares we find a clear CME event indicating that these must be very rare in active M-stars. However, in one relatively weak event, we found an asymmetry in the Balmer lines of ${\sim}220\, \rm km\, s^{-1}$, which we interpret as a signature of an erupting filament.

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A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209409 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 951-958

Author(s):

Tianhao Liu ◽

Yu Jin ◽

Cuixiang Pei ◽

Jie Han ◽

Zhenmao Chen

Keyword(s):

Power Plants ◽

Signal To Noise Ratio ◽

Small Diameter ◽

Performance Testing ◽

Guided Wave ◽

High Signal ◽

Receiver Coil ◽

Signal To Noise ◽

Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

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Computationally Assisted Design of High Signal-to-Noise Photoinduced Electron Transfer-Based Voltage-Sensitive Dyes

10.26434/chemrxiv.12401753 ◽

2020 ◽

Author(s):

Rishikesh Kulkarni ◽

Anneliese Gest ◽

Chun Kei Lam ◽

Benjamin Raliski ◽

Feroz James ◽

...

Keyword(s):

Electron Transfer ◽

Dft Calculations ◽

Photoinduced Electron Transfer ◽

Density Functional ◽

Embryonic Stem ◽

High Sensitivity ◽

Md Simulations ◽

High Signal ◽

Signal To Noise ◽

Green Fluorescent

<p>High signal-to-noise optical voltage indicators will enable simultaneous interrogation of membrane potential in large ensembles of neurons. However, design principles for voltage sensors with high sensitivity and brightness remain elusive, limiting the applicability of voltage imaging. In this paper, we use molecular dynamics (MD) simulations and density functional theory (DFT) calculations to guide the design of a bright and sensitive green-fluorescent voltage-sensitive fluorophore, or VoltageFluor (VF dye), that uses photoinduced electron transfer (PeT) as a voltage-sensing mechanism. MD simulations predict an 11% increase in sensitivity due to membrane orientation, while DFT calculations predict an increase in fluorescence quantum yield, but a decrease in sensitivity due to a decrease in rate of PeT. We confirm these predictions by synthesizing a new VF dye and demonstrating that it displays the expected improvements by doubling the brightness and retaining similar sensitivity to prior VF dyes. Combining theoretical predictions and experimental validation has resulted in the synthesis of the highest signal-to-noise green VF dye to date. We use this new voltage indicator to monitor the electrophysiological maturation of human embryonic stem cell-derived medium spiny neurons. </p>

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Electroanalysis of Catecholamine Drugs using Graphene Modified Electrodes

Current Analytical Chemistry ◽

10.2174/1573411014666180917113206 ◽

2019 ◽

Vol 15 (4) ◽

pp. 443-466 ◽

Cited By ~ 1

Author(s):

Mahya Karami Mosammam ◽

Mohammad Reza Ganjali ◽

Mona Habibi-Kool-Gheshlaghi ◽

Farnoush Faridbod

Keyword(s):

Electrochemical Sensors ◽

Modified Electrodes ◽

Electrochemical Methods ◽

High Signal ◽

Signal To Noise ◽

Low Level ◽

Biological Studies

Background: Catecholamine drugs are a family of electroactive pharmaceutics, which are widely analyzed through electrochemical methods. However, for low level online determination and monitoring of these compounds, which is very important for clinical and biological studies, modified electrodes having high signal to noise ratios are needed. Numerous materials including nanomaterials have been widely used as electrode modifies for these families during the years. Among them, graphene and its family, due to their remarkable properties in electrochemistry, were extensively used in modification of electrochemical sensors. Objective: In this review, working electrodes which have been modified with graphene and its derivatives and applied for electroanalyses of some important catecholamine drugs are considered.

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Narrow-frequency sharp-angular filters using all-dielectric cascaded meta-gratings

Nanophotonics ◽

10.1515/nanoph-2020-0141 ◽

2020 ◽

Vol 9 (10) ◽

pp. 3443-3450 ◽

Cited By ~ 1

Author(s):

Wei-Nan Liu ◽

Rui Chen ◽

Wei-Yi Shi ◽

Ke-Bo Zeng ◽

Fu-Li Zhao ◽

...

Keyword(s):

Thin Film ◽

Signal To Noise Ratio ◽

Incident Angle ◽

Design Strategy ◽

Transmission Peak ◽

High Signal ◽

Waveguide Array ◽

Signal To Noise ◽

Center Wavelength ◽

Noise Ratio

AbstractSelective transmission or filtering always responds to either frequency or incident angle, so as hardly to maximize signal-to-noise ratio in communication, detection and sensing. Here, we propose compact meta-filters of narrow-frequency sharp-angular transmission peak along with broad omnidirectional reflection sidebands, in all-dielectric cascaded subwavelength meta-gratings. The inherent collective resonance of waveguide-array modes and thin film approximation of meta-grating are employed as the design strategy. A unity transmission peak, locating at the incident angle of 44.4° and the center wavelength of 1550 nm, is demonstrated in a silicon meta-filter consisting of two-layer silicon rectangular meta-grating. These findings provide possibilities in cascaded meta-gratings spectroscopic design and alternative utilities for high signal-to-noise ratio applications in focus-free spatial filtering and anti-noise systems in telecommunications.

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