scholarly journals The Killer Fly Hunger Games: Target Size and Speed Predict Decision to Pursuit

2015 ◽  
Vol 86 (1) ◽  
pp. 28-37 ◽  
Author(s):  
Trevor J. Wardill ◽  
Katie Knowles ◽  
Laura Barlow ◽  
Gervasio Tapia ◽  
Karin Nordström ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Compound Eye ◽  
Matched Filter ◽  
Prey Size ◽  
Angular Size ◽  
Distance Estimation ◽  
Metabolic Cost ◽  
Size Estimation ◽  
Acceptance Angle ◽  
Predatory Response

Predatory animals have evolved to optimally detect their prey using exquisite sensory systems such as vision, olfaction and hearing. It may not be so surprising that vertebrates, with large central nervous systems, excel at predatory behaviors. More striking is the fact that many tiny insects, with their miniscule brains and scaled down nerve cords, are also ferocious, highly successful predators. For predation, it is important to determine whether a prey is suitable before initiating pursuit. This is paramount since pursuing a prey that is too large to capture, subdue or dispatch will generate a substantial metabolic cost (in the form of muscle output) without any chance of metabolic gain (in the form of food). In addition, during all pursuits, the predator breaks its potential camouflage and thus runs the risk of becoming prey itself. Many insects use their eyes to initially detect and subsequently pursue prey. Dragonflies, which are extremely efficient predators, therefore have huge eyes with relatively high spatial resolution that allow efficient prey size estimation before initiating pursuit. However, much smaller insects, such as killer flies, also visualize and successfully pursue prey. This is an impressive behavior since the small size of the killer fly naturally limits the neural capacity and also the spatial resolution provided by the compound eye. Despite this, we here show that killer flies efficiently pursue natural (Drosophila melanogaster) and artificial (beads) prey. The natural pursuits are initiated at a distance of 7.9 ± 2.9 cm, which we show is too far away to allow for distance estimation using binocular disparities. Moreover, we show that rather than estimating absolute prey size prior to launching the attack, as dragonflies do, killer flies attack with high probability when the ratio of the prey's subtended retinal velocity and retinal size is 0.37. We also show that killer flies will respond to a stimulus of an angular size that is smaller than that of the photoreceptor acceptance angle, and that the predatory response is strongly modulated by the metabolic state. Our data thus provide an exciting example of a loosely designed matched filter to Drosophila, but one which will still generate successful pursuits of other suitable prey.

scholarly journals High spatial resolution imaging of methane and other trace gases with the airborne Hyperspectral Thermal Emission Spectrometer (HyTES)

2016 ◽  
Author(s):  
G. C. Hulley ◽  
R. M. Duren ◽  
F. M. Hopkins ◽  
S. J. Hook ◽  
N. Vance ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Thermal Emission ◽  
High Spatial Resolution ◽  
Matched Filter ◽  
Study Data ◽  
High Spectral Resolution ◽  
Emission Sources ◽  
Source Attribution ◽  
Economic Sectors ◽  
Strong Emission

Abstract. Currently large uncertainties exist associated with the attribution and quantification of fugitive emissions of criteria pollutants and greenhouse gases such as methane across large regions and key economic sectors. In this study, data from the airborne Hyperspectral Thermal Emission Spectrometer (HyTES) have been used to develop robust and reliable techniques for the detection and wide-area mapping of emission plumes of methane and other atmospheric trace gas species over challenging and diverse environmental conditions with high spatial resolution that permits direct attribution to sources. HyTES is a pushbroom imaging spectrometer with high spectral resolution (256 bands from 7.5–12 µm), wide swath (1–2 km), and high spatial resolution (~2 m at 1 km altitude) that incorporates new thermal infrared (TIR) remote sensing technologies. In this study we introduce a hybrid Clutter Matched Filter (CMF) and plume dilation algorithm applied to HyTES observations to efficiently detect and characterize the spatial structures of individual plumes of CH4, H2S, NH3, NO2, and SO2 emitters. The sensitivity and field of regard of HyTES allows rapid and frequent airborne surveys of large areas including facilities not readily accessible from the surface. The HyTES CMF algorithm produces plume intensity images of methane and other gases from strong emission sources. The combination of high spatial resolution and multi-species imaging capability provides source attribution in complex environments. The CMF-based detection of strong emission sources over large areas is a fast and powerful tool needed to focus more computationally intensive retrieval algorithms to quantify emissions with error estimates, and is useful for expediting mitigation efforts and addressing critical science questions.

Physiological optics in the hummingbird hawkmoth: a compound eye without ommatidia

1999 ◽  
Vol 202 (5) ◽  
pp. 497-511 ◽  
Author(s):  
E. Warrant ◽  
K. Bartsch ◽  
C. Günther
Keyword(s):  
Spatial Resolution ◽  
Compound Eye ◽  
High Sensitivity ◽  
Diffraction Limit ◽  
Physiological Optics ◽  
Macroglossum Stellatarum ◽  
Superposition Eye ◽  
Eye Region

The fast-flying day-active hawkmoth Macroglossum stellatarum (Lepidoptera: Sphingidae) has a remarkable refracting superposition eye that departs radically from the classical principles of Exnerian superposition optics. Unlike its classical counterparts, this superposition eye is highly aspherical and contains extensive gradients of resolution and sensitivity. While such features are well known in apposition eyes, they were thought to be impossible in superposition eyes because of the imaging principle inherent in this design. We provide the first account of a superposition eye where these gradients are not only possible, but also produce superposition eyes of unsurpassed quality. Using goniometry and ophthalmoscopy, we find that superposition images formed in the eye are close to the diffraction limit. Moreover, the photoreceptors of the superposition eyes of M. stellatarum are organised to form local acute zones, one of which is frontal and slightly ventral, and another of which provides improved resolution along the equator of the eye. This angular packing of rhabdoms bears no resemblance to the angular packing of the overlying corneal facets. In fact, this eye has many more rhabdoms than facets, with up to four rhabdoms per facet in the frontal eye, a situation which means that M. stellatarum does not possess ommatidia in the accepted sense. The size of the facets and the area of the superposition aperture are both maximal at the frontal retinal acute zone. By having larger facets, a wider aperture and denser rhabdom packing, the frontal acute zone of M. stellatarum provides the eye with its sharpest and brightest image and samples the image with the densest photoreceptor matrix. It is this eye region that M. stellatarum uses to fixate flower entrances during hovering and feeding. This radical departure from classical Exnerian principles has resulted in a superposition eye which has not only high sensitivity but also outstanding spatial resolution.

Changes of Acuity during Light and Dark Adaptation in the Dragonfly Compound Eye

1990 ◽  
Vol 45 (1-2) ◽  
pp. 137-142 ◽  
Author(s):  
Eric J. Warrant ◽  
Robert B. Pinter
Keyword(s):  
Dark Adaptation ◽  
Time Course ◽  
Light Adaptation ◽  
Compound Eye ◽  
Sensitivity Function ◽  
The State ◽  
Intracellular Recordings ◽  
Acceptance Angle ◽  
Angular Sensitivity ◽  
Rapid Reduction

Abstract Intracellular recordings of angular sensitivity from the photoreceptors of Aeschnid dragonflies (Hemianax papuensis and Aeschna brevistyla) are used to determine the magnitude and time course of acuity changes following alterations of the state of light or dark adaptation. Acuity is defined on the basis of the acceptance angle, Δρ (the half-width of the angular-sensitivity function). The maximally light-adapted value of Δρ is half the dark-adapted value, indicating greater acuity during light adaptation. Following a change from light to dark adaptation, Δρ increases slowly, requiring at least 3 min to reach its dark-adapted value. In contrast, the reverse change (dark to light) induces a rapid reduction of Δρ , and at maximal adapting luminances, this reduction takes place in less than 10 sec.

Light guides in the dorsal eye of the male mayfly

1982 ◽  
Vol 216 (1202) ◽  
pp. 25-51 ◽  
Keyword(s):  
Ultraviolet Light ◽  
Compound Eye ◽  
Lucifer Yellow ◽  
Single Units ◽  
Polarization Sensitivity ◽  
Clear Zone ◽  
Tight Coupling ◽  
Acceptance Angle ◽  
Yellow Light ◽  
Light Guides

(i) The dorsal eyes are sensitive to ultraviolet light, which is focused by the corneal lens into crystalline cones in the region where these taper progressively to columns across the clear zone. The action of these columns as light guides can be observed in fixed eyes embedded in polymerized resin. In life the light guide part of the column is surrounded by watery non-cellular haemolymph. (ii) Shadowing the eye surface with a thin wire (three facets wide) while recording from individual receptor units shows that ultraviolet light reaches each receptor by its own facet as in an apposition eye, and not, as in a superposition eye, by a group of many facets. (iii) As shown by the dye Lucifer Yellow injected from a microelectrode, the electrophysiological unit consists of all seven retinula cells in the rhabdom region. Consistent with this tight coupling of retinula cells there is no polarization sensitivity. The peak spectral sensitivity of all single units is at 345-365 nm in the ultraviolet. The acceptance angle is 2.0–2.5°. The sensitivity at the spectral peak to a point source on the optical axis of the unit is poor compared to that in other insects tested with the same equipment. (iv) The acceptance angles (∆ ρ ) in the dorsal eye are at the theoretical minimum for the facet diameter and wavelength from diffraction theory. Ultraviolet vision, therefore, has made possible a reduction in facet size but the interommatidial angle ∆ ϕ is greater than expected from the optimum sampling theory of the diffraction limited compound eye. In fact ∆ ρ ≈ ∆ ϕ ≈ 2°. (v) The dorsal eye is effectively a foveal region with greater sampling density and narrower receptive fields but less overlap of fields than the lateral eye. (vi) The square cones and yellow screening pigment strongly suggest that there is superposition by reflexion of yellow light that spreads between ommatidia across the clear zone. This yellow light might photoreisomerize the visual pigment. Attempts to prove this theory during the recording from single units have so far failed but no better function for the clear zone has been suggested.

scholarly journals Interferometric Observations for O-Containing Organic Molecules Towards Orion-KL

1994 ◽  
Vol 140 ◽  
pp. 238-240
Author(s):  
Y. C. Minh ◽  
M. Ohishi ◽  
D. G. Roh ◽  
M. Ishiguro
Keyword(s):  
Spatial Distribution ◽  
Spatial Resolution ◽  
Organic Molecules ◽  
High Spatial Resolution ◽  
Angular Size ◽  
The Core ◽  
Resolution Observation ◽  
Total Column

AbstractHigh spatial resolution observation (~ 5 arcsec) were made for CH3OH, HCOOCH3, and (CH3)2O toward Orion-KL using the Nobeyama Millimeter Array. The spatial distribution of CH3OH appears to be well elongated along the line connecting IRc2 and “the southern condensation (SC)”. The HCOOCH3 and (CH3)2O emissions appear to be well concentrated to SC with an angular size of ~ 6.5 arcsec. We derive the total column densities 6.8 × 1017cm−2, 1.4 × 1016cm−2 and 2.7 × 1016cm−2 for CH3OH, HCOOCH3, and (CH3)2O, respectively, at the core of SC.

scholarly journals Methane Mapping with Future Satellite Imaging Spectrometers

2019 ◽  
Vol 11 (24) ◽  
pp. 3054 ◽  
Author(s):  
Alana K. Ayasse ◽  
Philip E. Dennison ◽  
Markus Foote ◽  
Andrew K. Thorpe ◽  
Sarang Joshi ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Infrared Imaging ◽  
Matched Filter ◽  
Signal To Noise Ratio ◽  
Point Sources ◽  
Anthropogenic Sources ◽  
Next Generation ◽  
Imaging Spectrometer ◽  
Satellite Imaging ◽  
Shortwave Infrared

This study evaluates a new generation of satellite imaging spectrometers to measure point source methane emissions from anthropogenic sources. We used the Airborne Visible and Infrared Imaging Spectrometer Next Generation(AVIRIS-NG) images with known methane plumes to create two simulated satellite products. One simulation had a 30 m spatial resolution with ~200 Signal-to-Noise Ratio (SNR) in the Shortwave Infrared (SWIR) and the other had a 60 m spatial resolution with ~400 SNR in the SWIR; both products had a 7.5 nm spectral spacing. We applied a linear matched filter with a sparsity prior and an albedo correction to detect and quantify the methane emission in the original AVIRIS-NG images and in both satellite simulations. We also calculated an emission flux for all images. We found that all methane plumes were detectable in all satellite simulations. The flux calculations for the simulated satellite images correlated well with the calculated flux for the original AVIRIS-NG images. We also found that coarsening spatial resolution had the largest impact on the sensitivity of the results. These results suggest that methane detection and quantification of point sources will be possible with the next generation of satellite imaging spectrometers.

Daily changes in the compound eye of a beetle ( Macrogyrus )

1983 ◽  
Vol 217 (1208) ◽  
pp. 265-285 ◽  
Keyword(s):  
Point Source ◽  
Light Adaptation ◽  
Compound Eye ◽  
Lucifer Yellow ◽  
Dense Layer ◽  
Clear Zone ◽  
Acceptance Angle ◽  
Crystalline Cone ◽  
Graded Index ◽  
Peak Sensitivity

(i) Graded index lenses in the cornea and the crystalline cone form the optical system in each ommatidium. (ii) By night the crystalline cone has a blunt ellipsoidal proximal end which contributes to the formation of a superposition image across the clear zone. By day the cone is a tapering point that is extended as a light guide through a dense layer of pigment. (iii) The action of extending the cone and moving the pigment towards the clear zone from between the cones occurs as the retinula-cell column contracts. (iv) Modelling of the ommatidial lens system shows how the superposition image is formed in the night eye, and suggests that axial rays are not well focused on the crystalline tract in the day eye. (v) All cells had peak sensitivity in the green near 552 nm. (vi) In the dark-adapted day eye, fields are ∆ ρ (acceptance angle) = 3.4–6.6°, narrowing to 2.8° minimum upon light adaptation. Sensitivity to a point source on axis is reduced during the day: the dark-adapted day eye requires 200 times more light to give the same response as the dark-adapted night eye. There is a further attenuation of about 100 upon light adaptation of the day eye. (vii) The superposition image of the night eye produces fields of width ∆ ρ = 12-15° at 50% sensitivity as recorded electrophysiologically, and therefore the image of a point source covers several rhabdoms. (viii) In recordings from single units in the night eye two bumps (effective photon captures) are counted when the intensity is such that one photon falls on the area of one facet, with parallel axial illumination at the peak of the spectral sensitivity, 552 nm. (ix) Marking of cells with Lucifer Yellow suggests that about four to six receptor units per ommatidium are involved, giving a sensitivity of eight to twelve bumps for the ommatidium at this intensity. (x) Locust apposition eyes, with facets twice the area of those in Macrogyrus eyes, give at best 0.5 bumps with the same intensity, so that the actual superposition gain is 32–48. (xi) All marked cells were of the proximal rhabdom layer; cells 1 and 8 have not been investigated.

Maximum prey size estimation of longtooth grouper,Epinephelus bruneus, using morphological features, and predation experiments on juvenile cannibalism

2014 ◽  
Vol 47 (2) ◽  
pp. 605-611 ◽  
Author(s):  
Nariaki Inoue ◽  
Jun Satoh ◽  
Tohru Mekata ◽  
Takashi Iwasaki ◽  
Koichiro Mori
Keyword(s):  
Prey Size ◽  
Morphological Features ◽  
Size Estimation ◽  
Epinephelus Bruneus

Visual Illusions in Frogs and Toads

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 80-80 ◽  
Author(s):  
V A Bastakov
Keyword(s):  
High Speed ◽  
Rana Temporaria ◽  
Angular Size ◽  
Distance Estimation ◽  
Bufo Bufo ◽  
Critical Distance ◽  
Moving Object ◽  
Small Object ◽  
Real Size ◽  
Escape Reaction

There are situations where frogs and toads radically misjudge the size of a moving object, taking an enemy for prey or vice versa. In the present work, the conditions where this occurs were investigated. Frogs ( Rana temporaria) were shown black balls of diameters 0.25 – 20 cm moving at different distances and velocities, either in the presence or absence of a structured background. When the targets moved at 10 – 15 cm s−1 (at a distance where this corresponded to ∼10 deg s−1) in the presence of the background, frogs turned, approached and tried to catch those with small diameters (0.25 – 2 cm) only. Larger targets mainly evoked escape reactions. Without the background, balls of any real size could be perceived as prey: all targets of angular size about 5 deg or less triggered a ‘food’ turning reaction, implying that the critical distance for this reaction depends linearly on object size. ‘Food’ turning towards big targets (10 or 20 cm) indicates incorrect distance estimation. Moreover, if a big target was moved at high speed (100 deg s−1), the frog not only turned but also flicked its tongue at it without approaching it, even when the distance was up to 1 m. Observations on the toad Bufo bufo were qualitatively similar. Thus it is possible to create an illusion of closeness in frogs and toads by increasing the speed of the moving object. Conversely, it is possible to create an illusion of distance by moving a small object at slow speed close to the animal. The 0.25 cm target moving at a 12 cm distance with a velocity of 0.15 cm s−1 (0.7 deg s−1) in the absence of the structured background evoked the ‘food’ reaction on only 4% of the trials and escape reactions on 80% of the trials. When the background was present, the same stimulus evoked ‘food’ turning only. The escape reaction to a small object can be explained by a drastic overestimation of its distance in the absence of other cues.

Mineral mapping at the Ikh Shankhai porphyry Cu deposits, Mongolia using WorldView-3 data

2020 ◽  
Author(s):  
Son Youngsun ◽  
Kim Kwang-Eun
Keyword(s):  
Spatial Resolution ◽  
Near Infrared ◽  
Matched Filter ◽  
Extreme Environments ◽  
Ground Truth ◽  
Spectral Signature ◽  
Ground Truth Data ◽  
Mineral Mapping ◽  
Porphyry Cu ◽  
Porphyry Cu Deposit

<p>Southeastern Mongolia has limited access due to its extreme environments (long and harsh winter) and lack of infrastructure (e.g., road). Satellite remote sensing technique is one of the most effective methods to get geological information in areas where field survey is difficult. WorldView-3 (WV3), launched in August 2014, is high-spatial resolution commercial multispectral sensor developed by DigitalGlobe. WV3 measures reflected radiation in eight visible near infrared (VNIR) bands between 0.42 and 1.04 ㎛ and in eight short-wave infrared (SWIR) bands between 1.20 and 2.33, which have 1.24- and 7.5-m spatial resolution, respectively. In this study, WV3 VNIR and SWIR data were used to identify and map the various minerals in the Ikh Shankhai porphyry Cu deposit district, Mongolia.</p><p>The Ikh-Shankhai porphyry Cu deposit is located within Gurvansayhan island arc terrane in southeastern (SE) Gobi mineral belt, Mongolia. The Ikh-Shankhai district include the porphyry system containing Cu-Au with primary chalcopyrite, which is classified into disseminated type and stockwork quartz type. This district consists of Late Devonian-Early Carboniferous andesite, tuff and siltstone intruded by Carboniferous-Permian granite, granodiorite and granodiorite porphyry.</p><p>The WV 3 data were analyzed using mixture-tuned-matched filter (MTMF) which locates a known spectral signature in the presence of a mixed or unknown background. MTMF does not require knowledge of all of the spectral endmembers and is suited for used where materials with distinct spectral signatures occur within a single pixel. From the WV3 analysis result using mixture-tuned-matched filter (MTMF), we identified the location and abundance of alteration minerals. Advanced argillic minerals (alunite, kaolinite (or dickite), and pyrophyllite) were dominant in the lithocaps of the Budgat and Gashuun Khudag prospects; whereas, phyllic (illite) and propylitic (calcite and epidote) minerals were dominant in the areas surrounding the lithocaps. In addition, the distribution of ferric minerals (hematite and goethite) was mapped because of the oxidation of pyrite. Field work at the Ikh-Shankhai porphyry Cu district to evaluate the accuracy of the mineral mapping results was carried out in August, 2018. Reflectance spectra acquisition using a portable ASD TerraSpec Halo mineral identifier (the attached GPS covered a spectral range of 0.35 – 2.5 µm) was conducted in the altered outcrops of the Ikh-Shankhai porphyry Cu district. Mineral mapping results compared well with the field spectral measurements collected for the ground truth and demonstrated WV3 capability for identifying and mapping minerals associated with hydrothermal alteration. Evaluation of the WV3 mineral mapping results using ground truth data indicates, however, a difficulty in mapping spectrally similar minerals (e.g., kaolinite and dickite) due to spectral resolution limitation.</p>

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