The marine gastropod Conomurex luhuanus (Strombidae) has high-resolution spatial vision and eyes with complex retinas

All species within the conch snail family Strombidae possess large camera-type eyes that are surprisingly well-developed compared to those found in most other gastropods. Although these eyes are known to be structurally complex, very little research on their visual function has been conducted. Here, we use isoluminant expanding visual stimuli to measure the spatial resolution and contrast sensitivity of a strombid, Conomurex luhuanus. Using these stimuli, we show that this species responds to objects as small as 1.06° in its visual field. We also show that C. luhuanus responds to Michelson contrasts of 0.07, a low contrast sensitivity between object and background. The defensive withdrawal response elicited by visual stimuli of such small angular size and low contrast suggests that conch snails may use spatial vision for the early detection of potential predators. We support these findings with morphological estimations of spatial resolution of 1.04 ± 0.14°. These anatomical data therefore agree with the behavioural measures and highlight the benefits of integrating morphological and behavioural approaches in animal vision studies. Furthermore, using contemporary imaging techniques including serial block-face scanning electron microscopy (SBF-SEM), in conjunction with transmission electron microscopy (TEM), we found that C. luhuanus have more complex retinas, in terms of cell type diversity, than previous studies of the group have discovered using TEM alone. We found the C. luhuanus retina is comprised of six cell types, including a newly identified ganglion cell and accessory photoreceptor, rather than the previously described four cell types.

Remnant Radio Galaxy Candidates of Small Angular Sizes

Remnant radio galaxies (RRGs), characterized by the cessation of AGN activity, represent a short-lived last phase of radio galaxy’s life-cycle. Hitherto, searches for RRGs, mainly based on the morphological criteria, have identified large angular size sources resulting into a bias towards the remnants of powerful FR-II radio galaxies. In this study we make the first attempt to perform a systematic search for RRGs of small angular sizes (<30′′) in the XMM−LSS field. By using spectral curvature criterion we discover 48 remnant candidates exhibiting strong spectral curvature i.e., α150MHz325MHz−α325MHz1.4GHz≥ 0.5. Spectral characteristics at higher frequency regime (>1.4 GHz) indicate that some of our remnant candidates can depict recurrent AGN activity with an active core. We place an upper limit on the remnant fraction (frem) to be 3.9%, which increases to 5.4% if flux cutoff limit of S150MHz≥ 10 mJy is considered. Our study unveils, hitherto unexplored, a new population of small-size (<200 kpc) remnant candidates that are often found to reside in less dense environments and at higher redshifts (z) > 1.0. We speculate that a relatively shorter active phase and/or low jet power can be plausible reasons for the small size of remnant candidates.

The HASHTAG Project: The First Submillimeter Images of the Andromeda Galaxy from the Ground

Observing nearby galaxies with submillimeter telescopes on the ground has two major challenges. First, the brightness is significantly reduced at long submillimeter wavelengths compared to the brightness at the peak of the dust emission. Second, it is necessary to use a high-pass spatial filter to remove atmospheric noise on large angular scales, which has the unwelcome side effect of also removing the galaxy’s large-scale structure. We have developed a technique for producing high-resolution submillimeter images of galaxies of large angular size by using the telescope on the ground to determine the small-scale structure (the large Fourier components) and a space telescope (Herschel or Planck) to determine the large-scale structure (the small Fourier components). Using this technique, we are carrying out the HARP and SCUBA-2 High Resolution Terahertz Andromeda Galaxy Survey (HASHTAG), an international Large Program on the James Clerk Maxwell Telescope, with one aim being to produce the first high-fidelity high-resolution submillimeter images of Andromeda. In this paper, we describe the survey, the method we have developed for combining the space-based and ground-based data, and we present the first HASHTAG images of Andromeda at 450 and 850 μm. We also have created a method to predict the CO(J = 3–2) line flux across M31, which contaminates the 850 μm band. We find that while normally the contamination is below our sensitivity limit, it can be significant (up to 28%) in a few of the brightest regions of the 10 kpc ring. We therefore also provide images with the predicted line emission removed.

Direct Measurements of Giant Star Effective Temperatures and Linear Radii: Calibration against Spectral Types and V − K Color

We calculate directly determined values for effective temperature (T eff) and radius (R) for 191 giant stars based upon high-resolution angular size measurements from optical interferometry at the Palomar Testbed Interferometer. Narrow- to wideband photometry data for the giants are used to establish bolometric fluxes and luminosities through spectral energy distribution fitting, which allows for homogeneously establishing an assessment of spectral type and dereddened V 0 − K 0 color; these two parameters are used as calibration indices for establishing trends in T eff and R. Spectral types range from G0III to M7.75III, V 0 − K 0 from 1.9 to 8.5. For the V 0 − K 0 = {1.9, 6.5} range, median T eff uncertainties in the fit of effective temperature versus color are found to be less than 50 K; over this range, T eff drops from 5050 to 3225 K. Linear sizes are found to be largely constant at 11 R ⊙ from G0III to K0III, increasing linearly with subtype to 50 R ⊙ at K5III, and then further increasing linearly to 150 R ⊙ by M8III. Three examples of the utility of this data set are presented: first, a fully empirical Hertzsprung–Russell diagram is constructed and examined against stellar evolution models; second, values for stellar mass are inferred based on measures of R and literature values for log g ; finally, an improved calibration of an angular size prediction tool, based upon V and K values for a star, is presented.

Discovery of 178 Giant Radio Galaxies in 1059 deg2 of the Rapid ASKAP Continuum Survey at 888 MHz

We report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that reach or exceed linear sizes on the order of one Megaparsec. We searched a contiguous area of 1059 deg2 from RAJ = 20h20m to 06h20m, and −50∘<DecJ<−40∘, which is covered by deep multi-band optical images of the Dark Energy Survey (DES) and in which previously only three ERGs larger than 1 Mpc had been reported. For over 1800 radio galaxy candidates inspected, our search in optical and infrared images resulted in hosts for 1440 ERG, for which spectroscopic and photometric redshifts from various references were used to convert their largest angular size (LAS) to projected linear size (LLS). This resulted in 178 newly discovered giant radio sources (GRS) with LLS >1 Mpc, of which 18 exceed 2 Mpc and the largest one is 3.4 Mpc. Their redshifts range from 0.02 to ∼2.0, but only 10 of the 178 new GRS have spectroscopic redshifts. For the 146 host galaxies, the median r-band magnitude and redshift are 20.9 and 0.64, while for the 32 quasars or candidates these are 19.7 and 0.75. Merging the six most recent large compilations of GRS results in 458 GRS larger than 1 Mpc, so we were able to increase this number by ∼39% to 636.

Improved Measurements of Molecular Cloud Distances Based on Global Search

The principle of the background-eliminated extinction-parallax (BEEP) method is examining the extinction difference between on- and off-cloud regions to reveal the extinction jump caused by molecular clouds, thereby revealing the distance in complex dust environments. The BEEP method requires high-quality images of molecular clouds and high-precision stellar parallaxes and extinction data, which can be provided by the Milky Way Imaging Scroll Painting (MWISP) CO survey and the Gaia DR2 catalog, as well as supplementary A V extinction data. In this work, the BEEP method is further improved (BEEP-II) to measure molecular cloud distances in a global search manner. Applying the BEEP-II method to three regions mapped by the MWISP CO survey, we collectively measured 238 distances for 234 molecular clouds. Compared with previous BEEP results, the BEEP-II method measures distances efficiently, particularly for those molecular clouds with large angular size or in complicated environments, making it suitable for distance measurements of molecular clouds in large samples.

Electrophysiological markers of advanced stages of glaucomatous optic neuropathy

Purpose: to determine the changes in electrophysiological parameters reflecting specific dysfunctions of retinal ganglion cells (RGCs) at advanced stages of glaucomatous optic neuropathy (GON).Material and methods. The study involved 35 patients (55 eyes) aged 51–76 (63.1 ± 7.7 years) with primary open-angle glaucoma (POAG), divided into two subgroups depending on POAG stages: developed (24 patients, 27 eyes) and advanced stages (24 patients, 28 eyes). The age-matched control group (aged 51–72, 59.8 ± 5.9) included 28 relatively healthy individuals (32 eyes). Transient and steady-state pattern ERG (PERG) and photopic negative response (PhNR) were recorded according to ISCEV standards.Results. A decrease in the amplitude of the transient PERG's N95 and P50-waves and steady-state PERG was found, the degree of which showed an inverse dependence on the angular size of the stimulus, which clearly distinguished the developed and advanced POAG stages from the initial GON. The developed stages are characterized by a decrease in the PhNR amplitude, calculated from the baseline, and the PhNR/b index, the reduction of which was the more significant the greater the intensity of the flash. A significant delay of the N95 peak for patterns of all angular sizes and a less pronounced lengthening of the latency of the P50 wave (significant only for small stimuli 0.8° and 0.3°) in comparison with the age norm were found. The latencies of the steady-state PERG and PhNR practically did not differ from the age norm values.Conclusion. The revealed reduction in the amplitudes of N95 and P50 waves of transient and steady-state PERG, PhNR, and the PhNR/b index, as well as an increase in the peak latency of N95 and P50 waves of transient PERG, may be markers of functional changes in the retina associated with non-adaptive plasticity or reflecting a combination of the processes of adaptive plasticity and degeneration of RGCs. Further research in this area will help give a more accurate characterization of the found regularities and apply the obtained results in clinical practice.

Automatic prediction, selection and analysis of occultations to characterize asteroid family members

&lt;p&gt;A new 50 cm telescope, the UniversCity telescope, was recently installed at Plateau de Calern, France, to survey stellar occultation by asteroids from collisional families. A stellar occultation occurs when an asteroid passes in front of a distant star blocking its light temporarily. Measuring the time of the occultations provides an accurate astrometric measurement of the asteroid, comparable with the angular size of the asteroid. Thanks to the astrometric catalog from the Gaia mission, astrometry accuracy from occultation reaches a few milliarcseconds.&lt;/p&gt;&lt;p&gt;The astrometry from the survey is used in turn to improve the orbit of the asteroid, while the duration of the occultation is used to constrain physical characteristics and search for binarity. The orbit improvement aims to detect and measure the drift rate in the orbital elements of asteroids due to the Yarkovsky effect, a non-gravitational force responsible for scattering the orbital elements of collisional family members. Combining the magnitude of the Yarkovsky drift rate from the occultation survey with the accumulated drift since the originating collision, the age determination of the collisional family can be obtained.&lt;/p&gt;&lt;p&gt;The occultation survey takes advantage of the stellar occultation technique and the Gaia astrometric catalog to systematically derive accurate astrometric measurements for collisional family members.&lt;/p&gt;&lt;p&gt;The telescope will be operated robotically, dedicating most of its time to the occultation survey, with a small percentage of time to other science cases. The large number of family members and candidates to stellar occultations demands the automation of the occultation prediction, the selection and prioritization of occultation events, telescope scheduling, data reduction, and data analysis.&lt;/p&gt;&lt;p&gt;The occultation predictions are updated regularly in the light of new astrometric measurements from traditional astrometry and from occultations measurements. The occultations predicted to be visible from the UniversCity site are prioritized based on their chances of detection and contribution to the family age determination. The data acquired each night is automatically reduced to obtain light curves from which detection candidates are analyzed.&lt;/p&gt;&lt;p&gt;We will present the status of the project and the development and performances of the automatic prediction and processing system.&lt;/p&gt;

Influencing the forming zone by altering the contact pressure in a bending process

In a modern production environment, flexible manufacturing methods are important because an overall trend towards mass customization and on-demand production is observed. Kinematic and incremental forming methods with generic tools can provide a large product variation but a deeper understanding of the forming mechanisms is required for process modelling, e.g. Incremental Swivel Bending (ISB). Particularly crucial is to identify the influences on the forming zone in order to purposefully control the material flow of a forming process. For a bending process where the bending moment is transmitted by clamping tools, this paper presents a method to alter the contact pressure distribution in order to affect the angular size and strain gradient of the forming zone. In the light of these results, the presented method can be deployed for a tooling with adaptive contact pressure to directly influence material flow, in particular using generic tools to overall provide a better control of flexible forming methods.