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Starlink satellite constellation: simulating its impact on optical observatories

SEA Icosaedro simulations May and June 2020 For the moment, all of them are based on the constellation profile starlink.dat, that considers some 12 thousand satellites. File: bv2020_microsatelites.pdf, report published in the Butlletin of the Spanish Astronomical Society (in Spanish language) All these tests include a photometric model of intermediate complexity, that takes into account distance to the observatory, phase angle, extinction (0.12 mag/airmass was selected for this bunch of simulations) and geometry of the shadow cone of the Earth. This model is very similar to that of Hainaut & Williams (2020) and our results may be directly compared to theirs. Affectation depends on the observatory latitude, but not on longitude. However, the main factors are the width of the field of view (FOV) and integration time (T). We performed tests for several different observatories available to the SEA community and this certainly illustrates latitude effects, but our results underline the strong importance of FOV and T and they are useful mainly to analyse these factors. Observatories and latitudes (degrees): Calar Alto      +037 Javalambre      +040 La Palma        +029 Montsec         +042 Paranal         -024 For each observatory (i.e., each latitude) we perform simulations of two kinds: 1) All-sky simulations: Counting the number of satellites visible as a function of time along one complete night --> For five different Sun declinations: +023, +012, +000, -012, -023 degrees --> For two different elevations over the horizon: satelites visible above +000 deg, and above +030 degrees So, in total, ten simulations are done at each location. File naming conventions: S_+LLL_+DDD_+HHH_NNN.xxx S: means "Starlink" +LLL: observatory latitude, degrees +DDD: Sun declination, degrees +HHH: Elevation over which satellites are counted, degrees NNN:  Number of individual interations that are averaged out (050 in all cases) xxx:  Type of file: xxx = jpg, ps, pdf, graphs with number of visible satellites as a function of time, time is measured from the previous noon and is given in mintutes, vertical lines indicate the instants of beginning and end of civil, nautical and astronomical twilights, and midnight. xxx = mp4, animation with the apparent magnitude histogram of visible satellites at one minute steps; background colour means: white in daylight, grey in civil twilight, light blue in nautical twilighg, deep blue in astronomical twilight, black during astronomical night xxx = dat, files with very detailed information about the simulation, not included here, but may be provided, with indications about their contents Example: S_+037_+012_+030_050.mp4 S: Starlink +037: Calar Alto latitude +012: Solar declination intermediate north +12 degrees +030: Counting satellites at 30 deg or more above horizon 050:  50 simulations were averaged mp4:  Movie with the histogram of apparent magnitudes 2) Pointing-oriented simulations: We select a FOV in arcminutes and an integration time T in seconds. Then, five observing directions are predefined: N, S, E, W at 45 deg elevation, and zenith For the given latitude we select Solar declination (0, +23, -23) and, both fixed, we study the five fields of view for three different solar elevations: -12, -25, -37, both PM and AM. This means that for one given observatory (latitude, FOV, T), 5 x 3 x 3 x 2 = 90 configurations, see: 5 pointing directions 3 solar declinations 3 solar elevations 2 for am/pm conditions This produces quite a large amount of information that is organised in form of detailed files and summary tables. Detailed files are: P_+LLL_+DDD_+HHH_pm_+aaa_+hhh_FOVi_iTim_NCRO.dat p_+LLL_+DDD_+HHH_pm_+aaa_+hhh_FOVi_iTim_NCRO.dat P: very detailed output, p: less detailed output +LLL: observatory latitude +DDD: Sun declination +HHH: Sun elevation pm = "pm" or "am" +aaa: observation azimuth from the South (O = S; 90 = W, 180 = N, 270 = E) +hhh: observation elevation (45 deg for NSEW, 90 deg for Z) FOVi: field of view in arcminutes iTim: integration time in seconds NCRO: number of crossing (multiple shots are simulated until NCRO sat crossings are registered, or until 1000 shots have been simulated) Detailed files are probably intersting only for very technical analysis, so they are not included here, but they may be provided upon request. The main results are contained in pdf tables that are, hopefully, self-explaining.

3D structure of the HII region Sh2-235 from tunable-filter optical observations

We present observations of the H-alpha, H-beta, [SII] 6716, 6731, [NII] 6583 emission lines in the galactic HII region Sh2-235 with the Mapper of Narrow Galaxy Lines (MaNGaL), a tunable filter at the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences.

zebrafish larva optic tectum

Drawing uploaded to scidraw.io on: 05 June 2020

zebrafish larva optic tectum

Drawing uploaded to scidraw.io on: 05 June 2020

opencc-by-4.0Jul 2020View details →

Low resolution scanned text dataset for optical character recognition

A collection of scanned pages of English text designed for testing low resolution OCR systems.  There are 11 different pieces of text, each of which contains 5 pages of text.  Each of these 55 pages is typeset in 18 different fonts and then scanned at 300 dpi, producing a total of 990 pages of scanned text.  Downsampled 60 dpi and 75 dpi versions are included.

opencc-zeroJun 2020View details →

Hooded crow genome assembly (PacBio long reads + BioNano optical maps + DoveTail HiC maps)

Structural variation (SV) is an important component of mutations providing the raw material for evolution. Here, we uncover the genome-wide spectrum of intra- and interspecific SV segregating in natural populations of seven songbird species in the genus Corvus. Combining short-read (N = 127) and long-read re-sequencing (N = 31), as well as optical mapping (N = 16), we apply both assembly- and read mapping approaches to detect SV and characterize a total of 220,452 insertions, deletions and inversions. We exploit sampling across wide phylogenetic timescales to validate SV genotypes and assess the contribution of SV to evolutionary processes in an avian model of incipient speciation. We reveal an evolutionary young (~530,000 years) cis-acting 2.25-kb retrotransposon insertion reducing expression of the NDP gene with consequences for premating isolation. Our results attest to the wealth and evolutionary significance of SV segregating in natural populations and highlight the need for reliable SV genotyping.

opencc-zeroJul 2020View details →

Data from: Persistent firing and adaptation in optic-flow-sensitive descending neurons

A general principle of sensory systems is that they adapt to prolonged stimulation by reducing their response over time. Indeed, in many visual systems, including higher-order motion sensitive neurons in the fly optic lobes and the mammalian visual cortex, a reduction in neural activity following prolonged stimulation occurs. In contrast to this phenomenon, the response of the motor system controlling flight maneuvers persists following the offset of visual motion. It has been suggested that this gap is caused by a lingering calcium signal in the output synapses of optic lobe neurons. However, whether this directly affects the responses of the post-synaptic descending neurons, leading to the observed behavioral output, is not known. We use extracellular electrophysiology to record from optic flow sensitive descending neurons in response to prolonged wide-field stimulation. We find that, as opposed to most sensory and visual neurons, and in particular to the motion vision sensitive neurons in the brains of flies and mammals, the descending neurons show little adaption during stimulus motion. In addition, we find that the optic flow sensitive descending neurons display persistent firing, or an after-effect, following the cessation of visual stimulation, consistent with the lingering calcium signal hypothesis. However, if the difference in after-effect is compensated for, subsequent presentation of stimuli in a test-adapt-test paradigm reveals adaptation to visual motion. Our results thus show a combination of adaptation and persistent firing, in the neurons that project to the thoracic ganglia, and thereby control behavioral output.

opencc-zeroAug 2020View details →

Effects of Mn6+ substitution on dielectric and optical characteristics of SrLaLiTeO6 double perovskite

In this paper, SrLaLiTe1-xMnxO6 (x = 0.02, 0.04, 0.06, 0.08, 0.10) double perovskites compounds have been prepared using solid state method. Studies on structural by applying X-ray diffraction (XRD) characterization found that all compounds formed in monoclinic, P21/n symmetry. As dopant concentration increased, field emission scanning electron microscope (FESEM) characterization used to found that larger grains were formed from x = 0.04 to x = 0.08 and affected dielectric properties studied by electrochemical impedance spectroscopy (EIS) characterization which showed enhancement of real dielectric permittivity, ε'. Dielectric property also showed non–Debye trend of DC conductivity, σDC. AC conductivity, σAC revealed frequency dependent plot that obey the universal power law at all temperatures applied and the σAC behaviour in SrLaLiTe1-xMnxO6 is due to the tunnelling of polarons.

opencc-zeroSep 2020View details →

Quantitative analysis of optical coherence tomography for neovascular age-related macular degeneration using deep learning

Purpose: To apply a deep learning algorithm for automated, objective, and comprehensive quantification of optical coherence tomography (OCT) scans to a large real-world dataset of eyes with neovascular age-related macular degeneration (AMD), and make the raw segmentation output data openly available for further research. Design: Retrospective analysis of OCT images from the Moorfields Eye Hospital AMD Database. Participants: 2473 first-treated eyes and another 493 second-treated eyes that commenced therapy for neovascular AMD between June 2012 and June 2017. Methods: A deep learning algorithm was used to segment all baseline OCT scans. Volumes were calculated for segmented features such as neurosensory retina (NSR), drusen, intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM), retinal pigment epithelium (RPE), hyperreflective foci (HRF), fibrovascular pigment epithelium detachment(fvPED), and serous PED (sPED). Analyses included comparisons between first and second eyes, by visual acuity (VA) and by race/ethnicity, and correlations between volumes. Main outcome measures: Volumes of segmented features (mm3), central subfield thickness (CST). Results: In first-treated eyes, the majority had both IRF and SRF (54.7%). First-treated eyes had greater volumes for all segmented tissues, with the exception of drusen, which was greater in second-treated eyes. In first-treated eyes, older age was associated with lower volumes for RPE, SRF, NSR and sPED; in second-treated eyes, older age was associated with lower volumes of NSR, RPE, sPED, fvPED and SRF. Eyes from black individuals had higher SRF, RPE and serous PED volumes, compared with other ethnic groups. Greater volumes of the vast majority of features were associated with worse VA. Conclusion: We report the results of large scale automated quantification of a novel range of baseline features in neovascular AMD. Major differences between first and second-treated eyes, with increasing age, and between ethnicities are highlighted. In the coming years, enhanced, automated OCT segmentation may assist personalization of real-world care, and the detection of novel structure-function correlations. These data will be made publicly available for replication and future investigation by the AMD research community.

opencc-zeroOct 2020View details →

Data for the effect of optic flow cues on honeybee flight control in wind

To minimise the risk of colliding with the ground or other obstacles, flying animals need to control both their ground speed and ground height. This task is particularly challenging in wind, where head winds require an animal to increase its airspeed to maintain a constant ground speed and tail winds may generate negative airspeeds, rendering flight more difficult to control. In this study, we investigate how head and tail winds affect flight control in the honeybee Apis mellifera, which is known to rely on the pattern of visual motion generated across the eye – known as optic flow – to maintain constant ground speeds and heights. We find that, when provided with optic flow cues in both the longitudinal and transverse directions of flight, honeybees maintain a constant ground speed but fly lower in head winds and higher in tail winds, a response that is also observed when longitudinal optic flow cues are minimised. This change in height with wind does not appear to result in a constant rate of optic flow in the ventral visual field, suggesting that honeybees may rely on a combination of mechanosensory and visual information when controlling flight in wind. We also find that, when the transverse component of optic flow is minimised, or when all optic flow cues are minimised, the effect of wind on ground height is abolished. We propose that the regular sidewards oscillations that the bees make as they fly may be used to extract information about the distance to the ground, independently of the longitudinal optic flow that they use for ground speed control. This computationally simple strategy could have potential uses in the development of lightweight and robust systems for guiding autonomous flying vehicles in natural environments.

opencc-by-4.0Oct 2020View details →

Dataset for: Sensitivity of a satellite algorithm for harmful algal blooms discrimination to the use of laboratory bio-optical data for training

Two files relating to the publication by Martinez-Vicente et al. (2020). meris_data_karenia_alt_chla.xlsx : file containing the chlorophyll concentrations for the different areas in the MODIS images selected for training and evaluation of the algorithm. coefficients_for_LDA_Karenia_mikimotoi.zip: file containing the coefficients for the Linear Discriminant Analysis (LDA) resulting from the training datasets 1,2 and 3.

opencc-by-4.0Oct 2020View details →

Identification of AKARI infrared sources by Deep HSC Optical Survey: Construction of New Band-Merged Catalogue on the NEP-Wide field

The corresponding paper published in MNRAS. https://<a href="https://doi.org/10.1093/mnras/staa3359">10.1093/mnras/staa3359</a>

opencc-by-4.0Dec 2020View details →

Dynamics of soliton self-injection locking in optical microresonators

<pre>The code and data used to produce the plots within the paper entitled "Dynamics of soliton self-injection locking in optical microresonators." </pre>

opencc-by-4.0Dec 2019View details →

Deep-tissue label-free quantitative optical tomography

Deep-tissue label-free quantitative optical tomography Jelle van der Horst, Anna K. Trull, and Jeroen Kalkman The data sets, software, and figures accompany the publication: "Deep-tissue label-free quantitative optical tomography", Optica 7, 1682 (2020)  <a href="https://doi.org/10.1364/OPTICA.397549">https://doi.org/10.1364/OPTICA.397549</a> <ul> <li>calc_hilbert_cor.m, corrects OCT data for dispersion</li> <li>cascade_measurement.m, analysis of OCT reference data<\li></li> <li>data_A2_polyfit_v1_slice_0198.zip, Peak fitted data for all 200 slices (200 files)<\li></li> <li>Ex18-11-01B, spectral-domain OCT reference data<\li></li> <li>Ex18-11-01D, spectral-domain OCT reference data for background<\li></li> <li>Ex18-11-01E_sweep_0001.dat, Reference power distribution of a sweep<\li></li> <li>loadframes_refdata.m, load spectral-domain OCT data<\li></li> <li>manual_COR_correction.m, perform manual center of rotation correction<\li></li> <li>run_frame_analysis_polyfit.m, fit spatial-domain OCT data<\li></li> <li>run_tomo_ocpt.m, main MATLAB file for the reconstruction <\li></li> <li>shift_correction_galvo.m, correction for galvo offset<\li></li> </ul>

opencc-zeroJan 2021View details →

Brewster angle optical reflection observation of self-limiting nanoparticle monolayer self-assembly at a liquid/liquid interface

Real-time optical reflection of incident p-polarized light near Brewster's angle shows that after drop-casting iron oxide nanoparticles (NPs) in heptane on top of a diethylene glycol (DEG) liquid substrate, an iron oxide NP layer forms at the DEG/heptane interface, and it self-limits to a monolayer even when there are excess NPs dispersed in the upper heptane phase. Most modes of NP self-assembly do not self-limit growth after the formation of a single monolayer. Observations are compared to a reflection model incorporating the reflectances expected at each interface. An effective medium model of the dielectric constant is used to model the reflectance of the NP layer at the DEG/heptane interface.

opencc-by-4.0Jan 2021View details →

Determination of complex refractive indices and optical properties of volcanic ashes in the thermal infrared based on generic petrological compositions: supplementary material

This dataset contains supplementary material to the paper "Determination of complex refractive indices and optical properties of volcanic ashes in the thermal infrared based on generic petrological compositions", doi: 10.1016/j.jvolgeores.2021.107174 It contains a set of volcanic ash refractive indices and optical properties derived for certain microphysical properties. For more information please consider the manuscript or contact the authors.

opencc-by-4.0Dec 2020View details →

Optical Trapping Data for the manuscript "Myosin with hypertrophic cardiomyopathy mutation R712L has a reduced working stroke which is rescued by omecamtiv mecarbil"

Optical Trapping Data for the manuscript "Myosin with hypertrophic cardiomyopathy mutation R712L has a reduced working stroke which is rescued by omecamtiv mecarbil"

opencc-by-4.0Jan 2021View details →

Modeled Atmospheric Optical and Thermodynamic Responses to an Exceptional Trans-Atlantic Dust Outbreak

Nine WRF-Chem 3.8.0 hindcasts, each utilizing a different dust emission configuration, from 1 March – 31 May 2015, coinciding with a Saharan air layer (SAL) dust outbreak during the 2015 Caribbean drought. WRF-Chem modeled aerosol optical depth (AOD) and Gálvez-Davison Index (GDI), a convective forecasting parameter, are provided in the files. These data correspond to the results published in "Modeled Atmospheric Optical and Thermodynamic Responses to an Exceptional Trans-Atlantic Dust Outbreak" by Paul Miller, Marcus Williams, and Thomas Mote, published the Journal of Geophysical Research: Atmospheres.

opencc-zeroDec 2014View details →

Data from: Keeping cool: enhanced optical reflection and heat dissipation in silver ants

Saharan silver ants, Cataglyphis bombycina, forage under extreme temperature conditions in the African desert. We show that the ants' conspicuous silvery appearance is created by a dense array of triangular hairs with two thermoregulatory effects. They enhance not only the reflectivity of the ant's body surface in the visible and near-infrared range of the spectrum, where solar radiation culminates, but also the emissivity of the ant in the mid-infrared. The latter effect enables the animals to efficiently dissipate heat back to the surroundings via blackbody radiation under full daylight conditions. This biological solution for a thermoregulatory problem may lead to the development of biomimetic coatings for passive radiative cooling of objects.