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https://www.readbyqxmd.com/read/28422088/clustering-by-fast-search-and-merge-of-local-density-peaks-for-gene-expression-microarray-data
#1
Rashid Mehmood, Saeed El-Ashram, Rongfang Bie, Hussain Dawood, Anton Kos
Clustering is an unsupervised approach to classify elements based on their similarity, and it is used to find the intrinsic patterns of data. There are enormous applications of clustering in bioinformatics, pattern recognition, and astronomy. This paper presents a clustering approach based on the idea that density wise single or multiple connected regions make a cluster, in which density maxima point represents the center of the corresponding density region. More precisely, our approach firstly finds the local density regions and subsequently merges the density connected regions to form the meaningful clusters...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28397644/holding-or-breaking-with-ptolemy-s-generalization-considerations-about-the-motion-of-the-planetary-apsidal-lines-in-medieval-islamic-astronomy
#2
S Mohammad Mozaffari
Argument In the Almagest, Ptolemy finds that the apogee of Mercury moves progressively at a speed equal to his value for the rate of precession, namely one degree per century, in the tropical reference system of the ecliptic coordinates. He generalizes this to the other planets, so that the motions of the apogees of all five planets are assumed to be equal, while the solar apsidal line is taken to be fixed. In medieval Islamic astronomy, one change in this general proposition took place because of the discovery of the motion of the solar apogee in the ninth century, which gave rise to lengthy discussions on the speed of its motion...
March 2017: Science in Context
https://www.readbyqxmd.com/read/28380873/ultrafast-electrical-spectrum-analyzer-based-on-all-optical-fourier-transform-and-temporal-magnification
#3
Yuhua Duan, Liao Chen, Haidong Zhou, Xi Zhou, Chi Zhang, Xinliang Zhang
Real-time electrical spectrum analysis is of great significance for applications involving radio astronomy and electronic warfare, e.g. the dynamic spectrum monitoring of outer space signal, and the instantaneous capture of frequency from other electronic systems. However, conventional electrical spectrum analyzer (ESA) has limited operation speed and observation bandwidth due to the electronic bottleneck. Therefore, a variety of photonics-assisted methods have been extensively explored due to the bandwidth advantage of the optical domain...
April 3, 2017: Optics Express
https://www.readbyqxmd.com/read/28358078/astronomy-landslides-cause-comet-eruptions
#4
(no author information available yet)
No abstract text is available yet for this article.
March 29, 2017: Nature
https://www.readbyqxmd.com/read/28332526/astronomy-star-orbits-close-to-black-hole
#5
(no author information available yet)
No abstract text is available yet for this article.
March 22, 2017: Nature
https://www.readbyqxmd.com/read/28328913/a-beacon-in-the-bush-becomes-an-astronomy-powerhouse
#6
Linda Nordling
No abstract text is available yet for this article.
March 22, 2017: Nature
https://www.readbyqxmd.com/read/28256847/precision-determination-of-the-small-x-gluon-from-charm-production-at-lhcb
#7
Rhorry Gauld, Juan Rojo
The small-x gluon in global fits of parton distributions is affected by large uncertainties from the lack of direct experimental constraints. In this Letter, we provide a precision determination of the small-x gluon from the exploitation of forward charm production data provided by LHCb for three different center-of-mass (c.m.) energies: 5 TeV, 7 TeV, and 13 TeV. The LHCb measurements are included in the parton distribution function (PDF) fit by means of normalized distributions and cross-section ratios between data taken at different c...
February 17, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28241639/solar-multi-conjugate-adaptive-optics-based-on-high-order-ground-layer-adaptive-optics-and-low-order-high-altitude-correction
#8
Lanqiang Zhang, Youming Guo, Changhui Rao
Multi-conjugate adaptive optics (MCAO) is the most promising technique currently developed to enlarge the corrected field of view of adaptive optics for astronomy. In this paper, we propose a new configuration of solar MCAO based on high order ground layer adaptive optics and low order high altitude correction, which result in a homogeneous correction effect in the whole field of view. An individual high order multiple direction Shack-Hartmann wavefront sensor is employed in the configuration to detect the ground layer turbulence for low altitude correction...
February 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28230129/astronomy-earth-s-seven-sisters
#9
Ignas A G Snellen
No abstract text is available yet for this article.
February 22, 2017: Nature
https://www.readbyqxmd.com/read/28230125/seven-temperate-terrestrial-planets-around-the-nearby-ultracool-dwarf-star-trappist-1
#10
Michaël Gillon, Amaury H M J Triaud, Brice-Olivier Demory, Emmanuël Jehin, Eric Agol, Katherine M Deck, Susan M Lederer, Julien de Wit, Artem Burdanov, James G Ingalls, Emeline Bolmont, Jeremy Leconte, Sean N Raymond, Franck Selsis, Martin Turbet, Khalid Barkaoui, Adam Burgasser, Matthew R Burleigh, Sean J Carey, Aleksander Chaushev, Chris M Copperwheat, Laetitia Delrez, Catarina S Fernandes, Daniel L Holdsworth, Enrico J Kotze, Valérie Van Grootel, Yaseen Almleaky, Zouhair Benkhaldoun, Pierre Magain, Didier Queloz
One aim of modern astronomy is to detect temperate, Earth-like exoplanets that are well suited for atmospheric characterization. Recently, three Earth-sized planets were detected that transit (that is, pass in front of) a star with a mass just eight per cent that of the Sun, located 12 parsecs away. The transiting configuration of these planets, combined with the Jupiter-like size of their host star-named TRAPPIST-1-makes possible in-depth studies of their atmospheric properties with present-day and future astronomical facilities...
February 22, 2017: Nature
https://www.readbyqxmd.com/read/28179655/astronomy-a-leisurely-way-to-visit-the-stars
#11
(no author information available yet)
No abstract text is available yet for this article.
February 8, 2017: Nature
https://www.readbyqxmd.com/read/28179654/astronomy-intermediate-mass-black-hole-found
#12
Kayhan Gültekin
No abstract text is available yet for this article.
February 8, 2017: Nature
https://www.readbyqxmd.com/read/28155883/first-on-site-true-gamma-ray-imaging-spectroscopy-of-contamination-near-fukushima-plant
#13
Dai Tomono, Tetsuya Mizumoto, Atsushi Takada, Shotaro Komura, Yoshihiro Matsuoka, Yoshitaka Mizumura, Makoto Oda, Toru Tanimori
We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution...
February 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28129150/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#14
Amir Kiperwas, Daniel Rosenfeld, Yonina C Eldar
We present an algorithm for resampling a function from its values on a non-Cartesian grid onto a Cartesian grid. This problem arises in many applications such as MRI, CT, radio astronomy and geophysics. Our algorithm, termed SParse Uniform ReSampling (SPURS), employs methods from modern sampling theory to achieve a small approximation error while maintaining low computational cost. The given non-Cartesian samples are projected onto a selected intermediate subspace, spanned by integer translations of a compactly supported kernel function...
November 1, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28113847/hyperspectral-image-super-resolution-via-non-negative-structured-sparse-representation
#15
Weisheng Dong, Fazuo Fu, Guangming Shi, Xun Cao, Jinjian Wu, Guangyu Li, Xin Li
Hyperspectral imaging has many applications from agriculture and astronomy to surveillance and mineralogy. However, it is often challenging to obtain High-resolution (HR) hyperspectral images using existing hyperspectral imaging techniques due to various hardware limitations. In this paper, we propose a new Hyperspectral image super-resolution method from a low-resolution (LR) image and a HR reference image of the same scene. The estimation of the HR hyperspectral image is formulated as a joint estimation of the hyperspectral dictionary and the sparse codes based on the prior knowledge of the spatialspectral sparsity of the hyperspectral image...
March 22, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28104845/your-self-driving-car-could-kill-radio-astronomy
#16
Daniel Clery
No abstract text is available yet for this article.
January 20, 2017: Science
https://www.readbyqxmd.com/read/28054609/astronomy-radio-burst-caught-red-handed
#17
COMMENT
Heino Falcke
No abstract text is available yet for this article.
January 4, 2017: Nature
https://www.readbyqxmd.com/read/28028226/single-pixel-interior-filling-function-approach-for-detecting-and-correcting-errors-in-particle-tracking
#18
Stanislav Burov, Patrick Figliozzi, Binhua Lin, Stuart A Rice, Norbert F Scherer, Aaron R Dinner
We present a general method for detecting and correcting biases in the outputs of particle-tracking experiments. Our approach is based on the histogram of estimated positions within pixels, which we term the single-pixel interior filling function (SPIFF). We use the deviation of the SPIFF from a uniform distribution to test the veracity of tracking analyses from different algorithms. Unbiased SPIFFs correspond to uniform pixel filling, whereas biased ones exhibit pixel locking, in which the estimated particle positions concentrate toward the centers of pixels...
January 10, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28005885/efficient-quantization-of-tunable-helix-phase-plates
#19
Adrian Grewe, Stefan Sinzinger
Helix phase plates are used in a variety of applications from optical trapping to astronomy. Tunable helix phase plates based on the Alvarez-Lohmann principle allow variation of the topological charge of the helix by rotating the phase plates with respect to each other around the optical axis. Current designs generate an undesired inverse phase in the section determined by the rotation angle. We present tunable phase plates that use a special quantization to maintain a uniform phase over the tuning range, suppressing the undesired part...
October 15, 2016: Optics Letters
https://www.readbyqxmd.com/read/28005872/flat-top-bandpass-filters-enabled-by-cascaded-resonant-gratings
#20
Yeong Hwan Ko, Robert Magnusson
Narrow bandpass filters are applied in laser systems, imaging, telecommunications, and astronomy. Traditionally implemented with thin-film stacks, there is recent interest in alternative means incorporating photonic resonance effects. Here, we demonstrate a new approach to bandpass filters that engages the guided-mode resonance effect working with a cavity-based Fabry-Perot resonance to flatten and steepen the pass band. Both of these resonance mechanisms are native to simple resonant bandpass filters placed in a cascade...
October 15, 2016: Optics Letters
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