RefPlanets: Search for reflected light from extrasolar planets with SPHERE/ZIMPOL

Aims. RefPlanets is a guaranteed time observation programme that uses the Zurich IMaging POLarimeter (ZIMPOL) of Spectro-Polarimetric High-contrast Exoplanet REsearch instrument at the Very Large Telescope to perform a blind search for exoplanets in wavelengths from 600 to 900 nm. The goals of this study are the characterisation of the unprecedented high polarimetic contrast and polarimetric precision capabilities of ZIMPOL for bright targets, the search for polarised reflected light around some of the closest bright stars to the Sun, and potentially the direct detection of an evolved cold exoplanet for the first time. Methods. For our observations of α Cen A and B, Sirius A, Altair, ɛ Eri and τ Ceti we used the polarimetricdifferential imaging (PDI) mode of ZIMPOL which removes the speckle noise down to the photon noise limit for angular separations ≿0.6′′. We describe some of the instrumental effects that dominate the noise for smaller separations and explain how to remove these additional noise effects in post-processing. We then combine PDI with angular differential imaging as a final layer of post-processing to further improve the contrast limits of our data at these separations. Results. For good observing conditions we achieve polarimetric contrast limits of 15.0–16.3 mag at the effective inner working angle of ~0.13′′, 16.3–18.3 mag at 0.5′′, and 18.8–20.4 mag at 1.5′′. The contrast limits closer in (≾0.6′′) display a significant dependence on observing conditions, while in the photon-noise-dominated regime (≿0.6′′) the limits mainly depend on the brightness of the star and the total integration time. We compare our results with contrast limits from other surveys and review the exoplanet detection limits obtained with different detection methods. For all our targets we achieve unprecedented contrast limits. Despite the high polarimetric contrasts we are not able to find any additional companions or extended polarised light sources in the data obtained so far.

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Revealing the Elemental Distribution Within Latent Fingermarks Using Synchrotron Sourced X-Ray Fluorescence Microscopy

10.26434/chemrxiv.7987247 ◽

2019 ◽

Author(s):

Rhiannon Boseley ◽

Buddhika Dorakumbura ◽

Daryl L. Howard ◽

martin de jonge ◽

Mark J. Tobin ◽

...

Keyword(s):

Fluorescence Microscopy ◽

Direct Detection ◽

Detection Methods ◽

Chemical Components ◽

Light Sources ◽

Elemental Distribution ◽

X Ray ◽

Organic Components ◽

Mapping Techniques ◽

Synchrotron Light Sources

<div><div><div><p>Fingermarks are an important form of crime-scene trace evidence; however, their usefulness may be hampered by a variation in response or a lack of robustness in detection methods. Understanding the chemical composition and distribution within fingermarks may help explain variation in latent fingermark detection with existing methods and identify new strategies to increase detection capabilities. The majority of research in the literature describes investigation of organic components of fingermark residue, leaving the elemental distribution less well understood. The relative scarcity of information regarding the elemental distribution within fingermarks is in part due to previous unavailability of direct, micron resolution elemental mapping techniques. This capability is now provided at third generation synchrotron light sources, where X-ray Fluorescence Microscopy (XFM) provides micron or sub-micron spatial resolution and direct detection with sub-μM detection limits. XFM has been applied in this study to reveal the distribution of inorganic components within fingermark residue, including endogenous trace metals (Fe, Cu, Zn), diffusible ions (Cl-, K+, Ca2+), and exogeneous metals (Ni, Ti, Bi). This study incorporated a multi-modal approach using XFM and Infrared Microspectroscopy (IRM) analyses to demonstrate co-localisation of endogenous metals within the hydrophilic organic components of fingermark residue. Additional experiments were then undertaken to investigate how sources of exogenous metals (e.g. coins and cosmetics) may be transferred to, and distributed within latent fingermarks. Lastly, this study reports a preliminary assessment of how environmental factors such as exposure to aqueous environments may effect elemental distribution within fingermarks. Taken together, the results of this study advance our current understanding of fingermark composition and its spatial distribution of chemical components, and may help explain detection variation observed during detection of fingermarks using standard forensic protocols.</p></div></div></div>

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Spectroscopic direct detection of reflected light from extrasolar planets

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stt1642 ◽

2013 ◽

Vol 436 (2) ◽

pp. 1215-1224 ◽

Cited By ~ 18

Author(s):

J. H. C. Martins ◽

P. Figueira ◽

N. C. Santos ◽

C. Lovis

Keyword(s):

Extrasolar Planets ◽

Direct Detection ◽

Reflected Light

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Revealing the Elemental Distribution Within Latent Fingermarks Using Synchrotron Sourced X-Ray Fluorescence Microscopy

10.26434/chemrxiv.7987247.v1 ◽

2019 ◽

Author(s):

Rhiannon Boseley ◽

Buddhika Dorakumbura ◽

Daryl L. Howard ◽

martin de jonge ◽

Mark J. Tobin ◽

...

Keyword(s):

Fluorescence Microscopy ◽

Direct Detection ◽

Detection Methods ◽

Chemical Components ◽

Light Sources ◽

Elemental Distribution ◽

X Ray ◽

Organic Components ◽

Mapping Techniques ◽

Synchrotron Light Sources

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Robust and fast post-processing of single-shot spin qubit detection events with a neural network

Scientific Reports ◽

10.1038/s41598-021-95562-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tom Struck ◽

Javed Lindner ◽

Arne Hollmann ◽

Floyd Schauer ◽

Andreas Schmidbauer ◽

...

Keyword(s):

Neural Network ◽

Neural Networks ◽

Bayesian Inference ◽

Rabi Oscillation ◽

Detection Methods ◽

Measured Signal ◽

Single Shot ◽

Post Processing ◽

Readout Signal ◽

Spin Qubit

AbstractEstablishing low-error and fast detection methods for qubit readout is crucial for efficient quantum error correction. Here, we test neural networks to classify a collection of single-shot spin detection events, which are the readout signal of our qubit measurements. This readout signal contains a stochastic peak, for which a Bayesian inference filter including Gaussian noise is theoretically optimal. Hence, we benchmark our neural networks trained by various strategies versus this latter algorithm. Training of the network with 106 experimentally recorded single-shot readout traces does not improve the post-processing performance. A network trained by synthetically generated measurement traces performs similar in terms of the detection error and the post-processing speed compared to the Bayesian inference filter. This neural network turns out to be more robust to fluctuations in the signal offset, length and delay as well as in the signal-to-noise ratio. Notably, we find an increase of 7% in the visibility of the Rabi oscillation when we employ a network trained by synthetic readout traces combined with measured signal noise of our setup. Our contribution thus represents an example of the beneficial role which software and hardware implementation of neural networks may play in scalable spin qubit processor architectures.

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Parametric Studies on ArtificialMorphoButterfly Wing Scales for Optical Device Applications

Journal of Nanomaterials ◽

10.1155/2015/451834 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7

Author(s):

Hyun Myung Kim ◽

Sang Hyeok Kim ◽

Gil Ju Lee ◽

Kyujung Kim ◽

Young Min Song

Keyword(s):

Gallium Phosphide ◽

High Sensitivity ◽

Membrane Thickness ◽

Light Sources ◽

Vapor Sensing ◽

Reflected Light ◽

Device Applications ◽

Parametric Studies ◽

Geometrical Effects ◽

Rigorous Coupled Wave

We calculated diffraction efficiencies of grating structures inspired byMorphobutterfly wings by using a rigorous coupled-wave analysis method. The geometrical effects, such as grating width, period, thickness, and material index, were investigated in order to obtain better optical performance. Closely packed grating structures with an optimized membrane thickness show vivid reflected colors and provide high sensitivity to surrounding media variations, which is applicable to vapor sensing or healthcare indicators.Morphostructures with high index materials such as zinc sulfide or gallium phosphide generate white color caused by broadband reflection that can be used as reflected light sources for display applications.

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Measurements of hydroperoxy radicals (HO<sub>2</sub>) at atmospheric concentrations using bromide chemical ionisation mass spectrometry

Atmospheric Measurement Techniques ◽

10.5194/amt-12-891-2019 ◽

2019 ◽

Vol 12 (2) ◽

pp. 891-902 ◽

Cited By ~ 4

Author(s):

Sascha R. Albrecht ◽

Anna Novelli ◽

Andreas Hofzumahaus ◽

Sungah Kang ◽

Yare Baker ◽

...

Keyword(s):

Water Vapour ◽

Mass Spectrometer ◽

Ion Source ◽

Detection Sensitivity ◽

Detection Methods ◽

Integration Time ◽

Key Species ◽

Atmospheric Concentrations ◽

Chemical Ionisation ◽

Ionisation Mass

Abstract. Hydroxyl and hydroperoxy radicals are key species for the understanding of atmospheric oxidation processes. Their measurement is challenging due to their high reactivity; therefore, very sensitive detection methods are needed. Within this study, the measurement of hydroperoxy radicals (HO2) using chemical ionisation combined with a high-resolution time-of-flight mass spectrometer (Aerodyne Research Inc.) employing bromide as the primary ion is presented. The sensitivity reached is equal to 0.005×108 HO2 cm−3 for 106 cps of bromide and 60 s of integration time, which is below typical HO2 concentrations found in the atmosphere. The detection sensitivity of the instrument is affected by the presence of water vapour. Therefore, a water-vapour-dependent calibration factor that decreases approximately by a factor of 2 if the water vapour mixing ratio increases from 0.1 % to 1.0 % needs to be applied. An instrumental background, most likely generated by the ion source that is equivalent to a HO2 concentration of (1.5±0.2)×108 molecules cm−3, is subtracted to derive atmospheric HO2 concentrations. This background can be determined by overflowing the inlet with zero air. Several experiments were performed in the atmospheric simulation chamber SAPHIR at the Forschungszentrum Jülich to test the instrument performance in comparison to the well-established laser-induced fluorescence (LIF) technique for measurements of HO2. A highly linear correlation coefficient of R2=0.87 is achieved. The slope of the linear regression of 1.07 demonstrates the good absolute agreement of both measurements. Chemical conditions during experiments allowed for testing the instrument's behaviour in the presence of atmospheric concentrations of H2O, NOx, and O3. No significant interferences from these species were observed. All of these facts demonstrate a reliable measurement of HO2 by the chemical ionisation mass spectrometer presented.

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Laboratory Demonstration of Spatial Linear Dark Field Control For Imaging Extrasolar Planets in Reflected Light

Publications of the Astronomical Society of the Pacific ◽

10.1088/1538-3873/aba9ad ◽

2020 ◽

Vol 132 (1016) ◽

pp. 104502

Author(s):

Thayne Currie ◽

Eugene Pluzhnik ◽

Olivier Guyon ◽

Ruslan Belikov ◽

Kelsey Miller ◽

...

Keyword(s):

Extrasolar Planets ◽

Dark Field ◽

Reflected Light ◽

Field Control

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A Novel Counterfeit Feature Extraction Technique for Exposing Face-Swap Images Based on Deep Learning and Error Level Analysis

Entropy ◽

10.3390/e22020249 ◽

2020 ◽

Vol 22 (2) ◽

pp. 249

Author(s):

Weiguo Zhang ◽

Chenggang Zhao ◽

Yuxing Li

Keyword(s):

Feature Extraction ◽

Deep Learning ◽

Image Compression ◽

Direct Detection ◽

Detection Methods ◽

Extraction Technique ◽

Error Level ◽

Face Area ◽

Level Analysis ◽

Feature Extraction Technique

The quality and efficiency of generating face-swap images have been markedly strengthened by deep learning. For instance, the face-swap manipulations by DeepFake are so real that it is tricky to distinguish authenticity through automatic or manual detection. To augment the efficiency of distinguishing face-swap images generated by DeepFake from real facial ones, a novel counterfeit feature extraction technique was developed based on deep learning and error level analysis (ELA). It is related to entropy and information theory such as cross-entropy loss function in the final softmax layer. The DeepFake algorithm is only able to generate limited resolutions. Therefore, this algorithm results in two different image compression ratios between the fake face area as the foreground and the original area as the background, which would leave distinctive counterfeit traces. Through the ELA method, we can detect whether there are different image compression ratios. Convolution neural network (CNN), one of the representative technologies of deep learning, can extract the counterfeit feature and detect whether images are fake. Experiments show that the training efficiency of the CNN model can be significantly improved by the ELA method. In addition, the proposed technique can accurately extract the counterfeit feature, and therefore achieves outperformance in simplicity and efficiency compared with direct detection methods. Specifically, without loss of accuracy, the amount of computation can be significantly reduced (where the required floating-point computing power is reduced by more than 90%).

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Emerging approaches for detection of methylation sites in RNA

Open Biology ◽

10.1098/rsob.180121 ◽

2018 ◽

Vol 8 (9) ◽

pp. 180121 ◽

Cited By ~ 11

Author(s):

Anna Ovcharenko ◽

Andrea Rentmeister

Keyword(s):

High Throughput Sequencing ◽

De Novo ◽

Direct Detection ◽

False Negative ◽

Detection Methods ◽

Rna Modifications ◽

Negative Results ◽

Third Generation Sequencing ◽

False Negative Results ◽

Generation Sequencing

RNA methylations play a significant regulatory role in diverse biological processes. Although the transcriptome-wide discovery of unknown RNA methylation sites is essential to elucidate their function, the development of a bigger variety of detection approaches is desirable for multiple reasons. Many established detection methods for RNA modifications heavily rely on the specificity of the respective antibodies. Thus, the development of antibody-independent transcriptome-wide methods is beneficial. Even the antibody-independent high-throughput sequencing-based methods are liable to produce false-positive or false-negative results. The development of an independent method for each modification could help validate the detected modification sites. Apart from the transcriptome-wide methods for methylation detection de novo , methods for monitoring the presence of a single methylation at a determined site are also needed. In contrast to the transcriptome-wide detection methods, the techniques used for monitoring purposes need to be cheap, fast and easy to perform. This review considers modern approaches for site-specific detection of methylated nucleotides in RNA. We also discuss the potential of third-generation sequencing methods for direct detection of RNA methylations.

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Challenges in vitamin D analysis / Izazovi u analizi vitamina D

Journal of Medical Biochemistry ◽

10.2478/v10011-012-0016-z ◽

2012 ◽

Vol 31 (4) ◽

pp. 326-332 ◽

Cited By ~ 1

Author(s):

Mustafa Serteser ◽

Abdurrahman Coskun ◽

Tamer C Inal ◽

Ibrahim Unsal

Keyword(s):

Vitamin D ◽

Clinical Laboratory ◽

Direct Detection ◽

Reference Method ◽

Detection Methods ◽

Binding Assays ◽

External Quality Assessment Scheme ◽

Specificity And Sensitivity ◽

Competitive Protein Binding ◽

Phosphorus Levels

Summary Vitamin D is an important determinant for the regulation of calcium and phosphorus levels and mineralization of the bone. The most reliable indicator of vitamin D status is the measurement of plasma or serum 25OH-D concentration. Several studies reported discrepancies between the results of assays. These high variabilities in 25OH-D measurements are due to used assay technologies and lack of standardization against the reference materials. Different assays have been employed for the measurement of 25OHD levels: Competitive Protein Binding Assays, immunoassays, direct detection methods. Choosing an assay platform is important both for clinical laboratory professionals and researchers, and several factors affect this process. Recently, liquid chromatography and tandem mass spectrometry is an alternative method to traditional assays and provides higher specificity and sensitivity than many assays; therefore, it has been suggested as a candidate reference method for circulating 25OH-D3. Standardization of methods for the quantification of 25OH-D by using the human-based samples would reduce the inter-method variability. The best way for laboratories to demonstrate the accuracy of their results is by participating in the external quality assessment scheme. Standardization of the assays is also required to provide clinicians with the accurate tools to diagnose hypovitaminosis. In addition, assay-specific decision limits are needed to define appropriate thresholds of treatment.

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