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Heino Falcke
No abstract text is available yet for this article.
January 4, 2017: Nature
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...
December 27, 2016: Proceedings of the National Academy of Sciences of the United States of America
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
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
Tailin Xu, Wanxin Shi, Jinrong Huang, Yongchao Song, Feilong Zhang, Li-Ping Xu, Xueji Zhang, Shutao Wang
The construction of the Space Station provides a spaceflight laboratory, which enables us to accomplish tremendous short- and long-duration research such as astronomy, physics, material sciences, and life sciences in a microgravity environment. Continuous innovation and development of spaceflight laboratory prompted us to develop a facile detection approach to meet stringent requirements in a microgravity environment that traditional experimental approaches cannot reach. Here we introduce superhydrophilic microwells onto superhydrophobic substrates that are capable of capturing and transferring microdroplets, demonstrating a proof-of-concept study of a biosensing platform toward microgravity application...
December 22, 2016: ACS Nano
P Darré, R Baudoin, J-T Gomes, N J Scott, L Delage, L Grossard, J Sturmann, C Farrington, F Reynaud, T A Ten Brummelaar
The Astronomical Light Optical Hybrid Analysis project investigates the combined use of a telescope array interferometer and nonlinear optics to propose a new generation of instruments dedicated to high-resolution imaging for infrared astronomy. The nonlinear process of optical frequency conversion transfers the astronomical light to a shorter wavelength domain. Here, we report on the first fringes obtained on the sky with the prototype operated at 1.55  μm in the astronomical H band and implemented on the Center for High Angular Resolution Astronomy telescope array...
December 2, 2016: Physical Review Letters
(no author information available yet)
No abstract text is available yet for this article.
December 14, 2016: Nature
C Philipp E Nothaft
The article introduces a previously unknown fourteenth-century treatise on computus and calendrical astronomy entitled Expositio kalendarii novi, whose author proposed elaborate solutions to the technical flaws inherent in the calendar used by the Roman Church. An analysis of verbal parallels to other contemporary works on the same topic makes it possible to establish that the Expositio was produced in the context of a calendar reform initiative led by Pope Clement VI in 1344/45 and that this anonymous text is probably identical to a 'great and laborious work' on the calendar that the monk Johannes de Termis prepared for the pope around this time...
January 2017: Annals of Science
Ellen T Arena, Curtis T Rueden, Mark C Hiner, Shulei Wang, Ming Yuan, Kevin W Eliceiri
Modern biological research particularly in the fields of developmental and cell biology has been transformed by the rapid evolution of the light microscope. The light microscope, long a mainstay of the experimental biologist, is now used for a wide array of biological experimental scenarios and sample types. Much of the great developments in advanced biological imaging have been driven by the digital imaging revolution with powerful processors and algorithms. In particular, this combination of advanced imaging and computational analysis has resulted in the drive of the modern biologist to not only visually inspect dynamic phenomena, but to quantify the involved processes...
December 2, 2016: Wiley Interdisciplinary Reviews. Developmental Biology
S Karki, D Tuyenbayev, S Kandhasamy, B P Abbott, T D Abbott, E H Anders, J Berliner, J Betzwieser, C Cahillane, L Canete, C Conley, H P Daveloza, N De Lillo, J R Gleason, E Goetz, K Izumi, J S Kissel, G Mendell, V Quetschke, M Rodruck, S Sachdev, T Sadecki, P B Schwinberg, A Sottile, M Wade, A J Weinstein, M West, R L Savage
The two interferometers of the Laser Interferometry Gravitational-wave Observatory (LIGO) recently detected gravitational waves from the mergers of binary black hole systems. Accurate calibration of the output of these detectors was crucial for the observation of these events and the extraction of parameters of the sources. The principal tools used to calibrate the responses of the second-generation (Advanced) LIGO detectors to gravitational waves are systems based on radiation pressure and referred to as photon calibrators...
November 2016: Review of Scientific Instruments
Fei Sun, Zhaoliang Cao, Yukun Wang, Caihua Zhang, Xingyun Zhang, Yong Liu, Quanquan Mu, Li Xuan
Almost all the deformable mirror (DM) based adaptive optics systems (AOSs) used on large aperture telescopes work at the infrared waveband due to the limitation of the number of actuators. To extend the imaging waveband to the visible, we propose a DM and Liquid crystal wavefront corrector (DM/LCWFC) combination AOS. The LCWFC is used to correct the high frequency aberration corresponding to the visible waveband and the aberrations of the infrared are corrected by the DM. The calculated results show that, to a 10 m telescope, DM/LCWFC AOS which contains a 1538 actuators DM and a 404 × 404 pixels LCWFC is equivalent to a DM based AOS with 4057 actuators...
November 28, 2016: Optics Express
Stephanie LaMassa
No abstract text is available yet for this article.
December 1, 2016: Nature
Takeru Matsuda, Fumiyasu Komaki
Many time series are naturally considered as a superposition of several oscillation components. For example, electroencephalogram (EEG) time series include oscillation components such as alpha, beta, and gamma. We propose a method for decomposing time series into such oscillation components using state-space models. Based on the concept of random frequency modulation, gaussian linear state-space models for oscillation components are developed. In this model, the frequency of an oscillator fluctuates by noise...
February 2017: Neural Computation
Luo Qi, Felix Just, Gerd Leuchs, Maria V Chekhova
Intensified charge coupled device (ICCD) cameras are widely used in vari-ous applications such as microscopy, astronomy, spectroscopy. Often they are used as single-photon detectors, with thresholding being an essential part of the readout. In this paper, we measure the quantum efficiency of an ICCD camera in the single-photon de-tection mode using the Klyshko absolute calibration technique. The quantum efficiency is obtained as a function of the threshold value and of the wavelength of the detected light. In addition, we study the homogeneity of the photon sensitivity over the camera chip area...
November 14, 2016: Optics Express
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
(no author information available yet)
No abstract text is available yet for this article.
3, 2016: Nature
Tengfei Wu, Ori Katz, Xiaopeng Shao, Sylvain Gigan
Recently introduced speckle correlations-based techniques enable noninvasive imaging of objects hidden behind scattering layers. In these techniques, the hidden object Fourier amplitude is retrieved from the scattered light autocorrelation, and the lost Fourier phase is recovered via iterative phase-retrieval algorithms, which suffer from convergence to wrong local minimums solutions and cannot solve ambiguities in object orientation. Here, inspired by notions used in astronomy, we experimentally demonstrate that in addition to Fourier amplitude, the object-phase information is naturally and inherently encoded in the scattered light bispectrum (the Fourier transform of triple correlation) and can also be extracted from a single high-resolution speckle pattern, based on which we present a single-shot imaging scheme to deterministically and unambiguously retrieve diffraction-limited images of objects hidden behind scattering layers...
November 1, 2016: Optics Letters
E Villa, J Cagigas, B Aja, L de la Fuente, E Artal
A 30% bandwidth phase shifter with four phase states is designed to be integrated in a radio astronomy receiver. The circuit has two 90° out-of-phase microwave phase-shifting branches which are combined by Wilkinson power dividers. Each branch is composed of a 180° phase shifter and a band-pass filter. The 180° phase shifter is made of cascaded hybrid rings with microwave PIN diodes as switching devices. The 90° phase shift is achieved with the two band-pass filters. Experimental characterization has shown significant results, with average phase shift values of -90...
September 2016: Review of Scientific Instruments
(no author information available yet)
No abstract text is available yet for this article.
20, 2016: Nature
(no author information available yet)
No abstract text is available yet for this article.
13, 2016: Nature
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