Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Binocular observations.
Articles de revues sur le sujet « Binocular observations »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Binocular observations ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Zhang, Bin, Kazuki Matsuura, Takafumi Mori, Janice M. Wensveen, Ronald S. Harwerth, Earl L. Smith et Yuzo Chino. « Binocular Deficits Associated With Early Alternating Monocular Defocus. II. Neurophysiological Observations ». Journal of Neurophysiology 90, no 5 (novembre 2003) : 3012–23. http://dx.doi.org/10.1152/jn.00975.2002.
Texte intégralRésumé :
Experiencing binocularly conflicting signals early in life dramatically alters the binocular responses of cortical neurons. Because visual cortex is highly plastic during a critical period of development, cortical deficits resulting from early abnormal visual experience often mirror the nature of interocular decorrelation of neural signals from the two eyes. In the preceding paper, we demonstrated that monkeys that experienced early alternating monocular defocus (–1.5, –3.0, or –6.0 D) show deficits in stereopsis that generally reflected the magnitude of imposed monocular defocus. Because these results indicated that alternating monocular defocus affected the higher spatial frequency components of visual scenes more severely, we employed microelectrode recording methods to investigate whether V1 neurons in these lens-reared monkeys exhibited spatial-frequency-dependent alterations in their binocular response properties. We found that a neuron's sensitivity to interocular spatial phase disparity was reduced in the treated monkeys and that this reduction was generally more severe for units tuned to higher spatial frequencies. In the majority of the affected units, the disparity-sensitivity loss was associated with interocular differences in monocular receptive field properties. The present results suggest that the behavioral deficits in stereopsis produced by abnormal visual experience reflect at least in part the constraints imposed by alterations at the earliest stages of binocular cortical processing and support the hypothesis that the local disparity processing mechanisms in primates are spatially tuned and can be independently compromised by early abnormal visual experience.
2
Wensveen, Janice M., Ronald S. Harwerth et Earl L. Smith. « Binocular Deficits Associated With Early Alternating Monocular Defocus. I. Behavioral Observations ». Journal of Neurophysiology 90, no 5 (novembre 2003) : 3001–11. http://dx.doi.org/10.1152/jn.00976.2002.
Texte intégralRésumé :
To study the binocular vision deficits associated with anisometropia, monkeys were reared with alternating monocular defocus, which allowed monocular mechanisms to develop normally while binocular mechanisms were selectively compromised. A defocusing contact lens of –1.5 D, –3 D, or –6 D was worn on alternate eyes on successive days ( n = 3 per lens power) from 3 wk to 9 mo of age. The control subjects were two normally reared monkeys and two human observers. Functional binocular vision was assessed through behavioral measurements of stereoscopic depth discrimination thresholds as a function of spatial frequency. To characterize the extent of the deficits in disparity processing at a given spatial frequency, the contrast required to support stereopsis was determined for a range of disparities that exceeded the subjects' measured stereoacuity. The lens-reared monkeys showed spatial-frequency-selective deficits in stereopsis that depended on the magnitude of the simulated anisometropia experienced during the rearing period. For a given spatial frequency, the treated monkeys generally required higher than normal contrasts to support stereopsis even for large disparities. Moreover, a given increase in contrast produced smaller than normal improvements in stereo discrimination in our treated subjects, which suggests that in addition to deficits in contrast sensitivity, disparity-sensitive mechanisms exhibited low contrast gains. The spatial-frequency selective nature of the binocular deficits produced by the imposed anisometropia indicate that disparity processing mechanisms are normally spatial-frequency selective and that mechanisms tuned to different spatial frequencies can be differentially affected by abnormal binocular visual experience.
3
Testa, V., R. P. Mignani, N. Rea, M. Marelli, D. Salvetti, A. A. Breeveld, F. Cusano et R. Carini. « Large Binocular Telescope observations of PSR J2043+2740* ». Monthly Notices of the Royal Astronomical Society 473, no 2 (27 septembre 2017) : 2000–2003. http://dx.doi.org/10.1093/mnras/stx2512.
Texte intégral
4
Read, Jenny C. A., et Bruce G. Cumming. « Testing Quantitative Models of Binocular Disparity Selectivity in Primary Visual Cortex ». Journal of Neurophysiology 90, no 5 (novembre 2003) : 2795–817. http://dx.doi.org/10.1152/jn.01110.2002.
Texte intégralRésumé :
Disparity-selective neurons in striate cortex (V1) probably implement the initial processing that supports binocular vision. Recently, much progress has been made in understanding the computations that these neurons perform on retinal inputs. The binocular energy model has been highly successful in providing a simple theory of these computations. A key feature of the energy model is that it is linear until after inputs from the two eyes are combined. Recently, however, a modified version of the energy model, incorporating threshold nonlinearities before binocular combination, has been proposed to account for the weaker disparity tuning observed with anticorrelated stimuli. In this study, we present new data needed for a critical assessment of these two models. We compare two key predictions of the models with responses of disparity-selective neurons recorded from V1 of awake fixating monkeys. We find that the original energy model, and a family of generalizations retaining linear binocular combination, are quantitatively inconsistent with the response of V1 neurons. In contrast, the modified version incorporating threshold nonlinearities can explain both sets of observations. We conclude that the energy model can be reconciled with experimental observations by adding a threshold before binocular combination. This gives us the clearest picture yet of the computation being carried out by disparity-selective V1 neurons.
5
de Kleer, Katherine, Michael Skrutskie, Jarron Leisenring, Ashley G. Davies, Al Conrad, Imke de Pater, Aaron Resnick et al. « Resolving Io’s Volcanoes from a Mutual Event Observation at the Large Binocular Telescope ». Planetary Science Journal 2, no 6 (12 novembre 2021) : 227. http://dx.doi.org/10.3847/psj/ac28fe.
Texte intégralRésumé :
Abstract Unraveling the geological processes ongoing at Io’s numerous sites of active volcanism requires high spatial resolution to, for example, measure the areal coverage of lava flows or identify the presence of multiple emitting regions within a single volcanic center. In de Kleer et al. (2017) we described observations with the Large Binocular Telescope during an occultation of Io by Europa at ∼6:17 UT on 2015 March 8 and presented a map of the temperature distribution within Loki Patera derived from these data. Here we present emission maps of three other volcanic centers derived from the same observation: Pillan Patera, Kurdalagon Patera, and the vicinity of Ulgen Patera/PV59/N Lerna Regio. The emission is localized by the light curves and resolved into multiple distinct emitting regions in two of the cases. Both Pillan and Kurdalagon Paterae had undergone eruptions in the months prior to our observations, and the location and intensity of the emission are interpreted in the context of the temporal evolution of these eruptions observed from other facilities. The emission from Kurdalagon Patera is resolved into two distinct emitting regions separated by only a few degrees in latitude that were unresolved by Keck observations from the same month.
6
Ono, Hiroshi, Nicholas J. Wade et Linda Lillakas. « Binocular Vision : Defining the Historical Directions ». Perception 38, no 4 (1 janvier 2009) : 492–507. http://dx.doi.org/10.1068/p6130.
Texte intégralRésumé :
Ever since Kepler described the image-forming properties of the eye (400 years ago) there has been a widespread belief, which remains to this day, that an object seen with one eye is always seen where it is. Predictions made by Ptolemy in the first century, Alhazen in the eleventh, and Wells in the eighteenth, and supported by Towne, Hering, and LeConte in the nineteenth century, however, are contrary to this claimed veridicality. We discuss how among eighteenth-and nineteenth-century British researchers, particularly Porterfield, Brewster, and Wheatstone, the erroneous idea continued and also why observations made by Wells were neither understood nor appreciated. Finally, we discuss recent data, obtained with a new method, that further support Wells's predictions and which show that a distinction between headcentric and relative direction tasks is needed to appreciate the predictions.
7
Freeman, Alan W. « Multistage Model for Binocular Rivalry ». Journal of Neurophysiology 94, no 6 (décembre 2005) : 4412–20. http://dx.doi.org/10.1152/jn.00557.2005.
Texte intégralRésumé :
Binocular rivalry is the alternating perception that occurs when incompatible stimuli are presented to the two eyes: one monocular stimulus dominates vision and then the other stimulus dominates, with a perceptual switch occurring every few seconds. There is a need for a binocular rivalry model that accounts for both well-established results on the timing of dominance intervals and for more recent evidence on the distributed neural processing of rivalry. The model for binocular rivalry developed here consists of four parallel visual channels, two driven by the left eye and two by the right. Each channel consists of several consecutive processing stages representing successively higher cortical levels, with mutual inhibition between the channels at each stage. All stages are architecturally identical. With n the number of stages, the model is implemented as 4 n nonlinear differential equations using a total of eight parameters. Despite the simplicity of its architecture, the model accounts for a variety of experimental observations: 1) the increasing depth of rivalry at higher cortical areas, as shown in electrophysiological, imaging, and psychophysical experiments; 2) the unimodal probability density of dominance durations, where the mode is less than the mean; 3) the lack of correlation between successive dominance durations; 4) the effect of interocular stimulus differences on dominance duration; and 5) eye suppression, as opposed to feature suppression. The model is potentially applicable to issues of visual processing more general than binocular rivalry.
8
Xie, Wanyi, Yiren Wang, Yingwei Xia, Zhenyu Gao et Dong Liu. « Angular Calibration of Visible and Infrared Binocular All-Sky-View Cameras Using Sun Positions ». Remote Sensing 13, no 13 (23 juin 2021) : 2455. http://dx.doi.org/10.3390/rs13132455.
Texte intégralRésumé :
Visible and infrared binocular all-sky-view cameras can provide continuous and complementary ground-based cloud observations. Accurate angular calibration for every pixel is an essential premise to further cloud analysis and georeferencing. However, most current calibration methods mainly rely on calibration plates, which still remains difficult for simultaneously calibrating visible and infrared binocular cameras, especially with different imaging resolutions. Thus, in this study, we present a simple and convenient angular calibration method for wide field-of-view visible and infrared binocular cameras. Without any extra instruments, the proposed method only utilizes the relation between the angular information of direct sun lights and the projected sun pixel coordinates to compute the geometric imaging parameters of the two cameras. According to the obtained parameters, the pixel-view-angle for the visible and infrared all-sky images is efficiently computed via back projection. Meanwhile, the projected pixel coordinates for the incident lights at any angle can also be computed via reprojection. Experimental results show the effectiveness and accuracy of the proposed angular calibration through the error estimation of reprojection and back projection. As a novel application, we successfully achieve visible and infrared binocular image registration at the pixel level after finishing angular calibration, which not only verifies the accuracy of calibration results, but also contributes to further cloud parameter analysis under these two different imaging features. The registration results, to our knowledge, also provide a reference for the current blank in visible and infrared binocular cloud image registration.
9
Ashcraft, Teresa A., Tyler McCabe, Caleb Redshaw, Rogier A. Windhorst, Rolf A. Jansen, Seth H. Cohen, Timothy Carleton et al. « Deep Large Binocular Camera r-band Observations of the GOODS-N Field ». Publications of the Astronomical Society of the Pacific 135, no 1044 (1 février 2023) : 024101. http://dx.doi.org/10.1088/1538-3873/aca1e0.
Texte intégralRésumé :
Abstract We obtained 838 Sloan r-band images (∼28 hr) of the GOODS-North field with the Large Binocular Camera (LBC) on the Large Binocular Telescope in order to study the presence of extended, low surface brightness features in galaxies and investigate the trade-off between image depth and resolution. The individual images were sorted by effective seeing, which allowed for optimal resolution and optimal depth mosaics to be created with all images with seeing FWHM < 0.″9 and FWHM < 2.″0, respectively. Examining bright galaxies and their substructure as well as accurately deblending overlapping objects requires the optimal resolution mosaic, while detecting the faintest objects possible (to a limiting magnitude of m AB ∼ 29.2 mag) requires the optimal depth mosaic. The better surface brightness sensitivity resulting from the larger LBC pixels, compared to those of extant WFC3/UVIS and ACS/WFC cameras aboard the Hubble Space Telescope allows for unambiguous detection of both diffuse flux and very faint tidal tails. Azimuthally-averaged radial surface brightness profiles were created for the 360 brightest galaxies in each of the two mosaics. On average, these profiles showed minimal difference between the optimal resolution and optimal depth surface brightness profiles. However, ≲15% of the profiles show excess flux in the galaxy outskirts down to surface brightness levels of μ r AB ≃ 31 mag arcsec−2. This is relevant to Extragalactic Background Light (EBL) studies as diffuse light in the outer regions of galaxies are thought to be a major contribution to the EBL. While some additional diffuse light exists in the optimal depth profiles compared to the shallower, optimal resolution profiles, we find that diffuse light in galaxy outskirts is a minor contribution to the EBL overall in the r-band.
10
Blais, Brian S., Mikhail Y. Frenkel, Scott R. Kuindersma, Rahmat Muhammad, Harel Z. Shouval, Leon N. Cooper et Mark F. Bear. « Recovery From Monocular Deprivation Using Binocular Deprivation ». Journal of Neurophysiology 100, no 4 (octobre 2008) : 2217–24. http://dx.doi.org/10.1152/jn.90411.2008.
Texte intégralRésumé :
Ocular dominance (OD) plasticity is a robust paradigm for examining the functional consequences of synaptic plasticity. Previous experimental and theoretical results have shown that OD plasticity can be accounted for by known synaptic plasticity mechanisms, using the assumption that deprivation by lid suture eliminates spatial structure in the deprived channel. Here we show that in the mouse, recovery from monocular lid suture can be obtained by subsequent binocular lid suture but not by dark rearing. This poses a significant challenge to previous theoretical results. We therefore performed simulations with a natural input environment appropriate for mouse visual cortex. In contrast to previous work, we assume that lid suture causes degradation but not elimination of spatial structure, whereas dark rearing produces elimination of spatial structure. We present experimental evidence that supports this assumption, measuring responses through sutured lids in the mouse. The change in assumptions about the input environment is sufficient to account for new experimental observations, while still accounting for previous experimental results.
11
Stollenwerk, Lars, et Mathias Bode. « Lateral Neural Model of Binocular Rivalry ». Neural Computation 15, no 12 (1 décembre 2003) : 2863–82. http://dx.doi.org/10.1162/089976603322518777.
Texte intégralRésumé :
This article introduces a two-dimensionally extended, neuron-based model for binocular rivalry. The basic block of the model is a certain type of astable multivibrator comprising excitatory and inhibitory neurons. Many of these blocks are laterally coupled on a medium range to provide a two-dimensional layer. Our model, like others, needs noise to reproduce typical stochastic oscillations. Due to its spatial extension, the noise has to be laterally correlated. When the contrast ratio of the pictures varies, their share of the perception time changes in a way that is known from comparable experimental data (Levelt, 1965; Mueller & Blake, 1989). This is a result of the lateral coupling and not a property of the single model block. The presentation of simple and suitable inhomogeneous stimuli leads to an easily describable perception of periodically moving pictures like propagating fronts or breathing spots. This suggests new experiments. Under certain conditions, a bifurcation from static to moving perceptions is predicted and may be checked and employed by future experiments. Recent “paradox” (Logothetis, 1999) observations of two different neuron classes in cortical areas MT (Logothetis & Schall, 1989) and V4 (Leopold & Logothetis, 1996), one that behaves alike under rivaling and nonrivaling conditions and another that drastically changes its behavior, are interpreted as being related to separate inhibitor neurons.
12
Dineva, Ekaterina, Carsten Denker, Meetu Verma, Klaus G. Strassmeier, Ilya Ilyin et Ivan Milic. « Sun-as-a-star observations of the 2017 August 21 solar eclipse ». Proceedings of the International Astronomical Union 15, S354 (juin 2019) : 473–80. http://dx.doi.org/10.1017/s1743921319010019.
Texte intégralRésumé :
AbstractThe Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) is a state-of-the-art, thermally stabilized, fiber-fed, high-resolution spectrograph for the Large Binocular Telescope (LBT) at Mt. Graham, Arizona. During daytime the instrument is fed with sunlight from the 10-millimeter aperture, fully automated, binocular Solar Disk-Integrated (SDI) telescope. The observed Sun-as-a-star spectra contain a multitude of photospheric and chromospheric spectral lines in the wavelength ranges 4200–4800 Å and 5300–6300 Å. One of the advantages of PEPSI is that solar spectra are recorded in the exactly same manner as nighttime targets. Thus, solar and stellar spectra can be directly compared. PEPSI/SDI recorded 116 Sun-as-a-star spectra during the 2017 August 21 solar eclipse. The observed maximum obscuration was 61.6%. The spectra were taken with a spectral resolution of ≈ 250000 and an exposure time of 0.3 s. The high-spectral resolution facilitates detecting subtle changes in the spectra while the Moon passes the solar disk. Sun-as-a-star spectra are affected by changing contributions due to limb darkening and solar differential rotation, and to a lesser extend by supergranular velocity pattern and the presence of active regions on the solar surface. The goal of this study is to investigate the temporal evolution of the chromospheric Na D doublet during the eclipse and to compare observations with synthetic line profiles computed with the state-of-the-art Bifrost code.
13
Perna, M., M. Curti, G. Cresci, F. Mannucci, S. Rabien, C. Grillo, S. Belli et al. « LBT/ARGOS adaptive optics observations of z ∼ 2 lensed galaxies ». Astronomy & ; Astrophysics 618 (octobre 2018) : A36. http://dx.doi.org/10.1051/0004-6361/201732387.
Texte intégralRésumé :
Aims. Gravitationally lensed systems allow a detailed view of galaxies at high redshift. High spatial- and spectral-resolution measurements of arc-like structures can offer unique constraints on the physical and dynamical properties of high-z systems. Methods. We present near-infrared spectra centred on the gravitational arcs of six known z ∼ 2 lensed star-forming galaxies of stellar masses of 109−11 M⊙ and star formation rate (SFR) in the range between 10 and 400 M⊙ yr−1. Ground layer adaptive optics (AO)-assisted observations are obtained at the Large Binocular Telescope (LBT) with the LUCI spectrographs during the commissioning of the ARGOS facility. We used MOS masks with curved slits to follow the extended arched structures and study the diagnostic emission lines. LBT observations are used to demonstrate the spectroscopic capabilities of ARGOS. Results. Combining spatially resolved kinematic properties across the arc-like morphologies, emission line diagnostics and archival information, we distinguish between merging and rotationally supported systems, and reveal the possible presence of ejected gas. For galaxies that have evidence for outflows, we derive outflow energetics and mass-loading factors compatible with those observed for stellar winds in local and high-z galaxies. We also use flux ratio diagnostics to derive gas-phase metallicities. The low signal-to-noise ratio in the faint Hβ and nitrogen lines allows us to derive an upper limit of ≈0.15 dex for the spatial variations in metallicity along the slit for the lensed galaxy J1038. Conclusions. Analysed near-infrared spectra presented here represent the first scientific demonstration of performing AO-assisted multi-object spectroscopy with narrow curved-shape slits. The increased angular and spectral resolution, combined with the binocular operation mode with the 8.4 m wide eyes of LBT, will allow the characterisation of kinematic and chemical properties of a large sample of galaxies at high-z in the near future.
14
Tabandeh, H., L. Ranganath et V. Marks. « Visual Function during Acute Hypoglycaemia ». European Journal of Ophthalmology 6, no 1 (janvier 1996) : 81–86. http://dx.doi.org/10.1177/112067219600600116.
Texte intégralRésumé :
Hypoglycaemia symptoms are of particular interest in view of the importance of hypoglycaemia unawareness. Visual symptoms arising during acute hypoglycaemia may be the result of metabolic disturbances in the visual pathways within the central nervous system or impairment of the refractive apparatus of the eye and binocular function. This study investigated the effect of hypoglycaemia upon visual acuity, binocular interaction and contrast sensitivity. Various aspects of visual function were examined in ten normal subjects before, during and after acute insulin-induced hypoglycaemia. A simultaneous study of hypoglycaemic symptoms enabled us to relate the objective findings to the symptoms as reported by the subjects. Snellen visual acuity, fusion and stereopsis were not affected by hypoglycaemia. Five subjects noted visual disturbance. Eight developed significant impairment of contrast sensitivity, which closely matched the lowered blood glucose concentration. These observations suggest that hypoglycaemic visual symptoms are due to neuroglycopenia of central visual pathways rather than changes within the refractive apparatus or abnormality of binocular function. Although these symptoms are not a constant feature of the hypoglycaemic state, subtle impairment of visual function occurs in most cases. Contrast sensitivity testing can be useful for assessment of fine changes in visual function.
15
Verhoef, Bram-Ernst, Rufin Vogels et Peter Janssen. « Binocular depth processing in the ventral visual pathway ». Philosophical Transactions of the Royal Society B : Biological Sciences 371, no 1697 (19 juin 2016) : 20150259. http://dx.doi.org/10.1098/rstb.2015.0259.
Texte intégralRésumé :
One of the most powerful forms of depth perception capitalizes on the small relative displacements, or binocular disparities, in the images projected onto each eye. The brain employs these disparities to facilitate various computations, including sensori-motor transformations (reaching, grasping), scene segmentation and object recognition. In accordance with these different functions, disparity activates a large number of regions in the brain of both humans and monkeys. Here, we review how disparity processing evolves along different regions of the ventral visual pathway of macaques, emphasizing research based on both correlational and causal techniques. We will discuss the progression in the ventral pathway from a basic absolute disparity representation to a more complex three-dimensional shape code. We will show that, in the course of this evolution, the underlying neuronal activity becomes progressively more bound to the global perceptual experience. We argue that these observations most probably extend beyond disparity processing per se , and pertain to object processing in the ventral pathway in general. We conclude by posing some important unresolved questions whose answers may significantly advance the field, and broaden its scope. This article is part of the themed issue ‘Vision in our three-dimensional world’.
16
Dall’Oglio, G., A. Miriametro, G. Morgante, L. Pizzo et L. Valenziano. « An Instrument Devoted to the Study of mm/sub-mm Galactic Emission at Dome C ». Publications of the Astronomical Society of Australia 13, no 1 (janvier 1996) : 44–47. http://dx.doi.org/10.1017/s1323358000020518.
Texte intégralRésumé :
AbstractAn experiment has been developed in order to map the submillimetre Galactic emission at four different wavelengths between 400 μm and 2 mm at an angular scale of 1°. A binocular telescope system has been realised by means of two off-axis wobbling parabolic mirrors, each one coupled to a two-channel 3He photometer. A first run of observations from Dome C is planned for the Antarctic summer 1995–96.
17
Patil, Kishor G., Deeksha Dabrase et Virendra A. Shende. « Birds of Rawanwadi Region Bhandara, Central India ». Malaysian Journal of Medical and Biological Research 5, no 2 (31 décembre 2018) : 109–16. http://dx.doi.org/10.18034/mjmbr.v5i2.459.
Texte intégralRésumé :
The region of Rawanwadi reservoir is a good habitat for insects, fishes, reptiles as well as birds. Its geographical location is 21.043197 N, 79.729924 E. Observations were done by two visits on every month from May 2015 to April 2016 in the morning and evening hours. Bird observation and recording were done with the help of binocular and digital cameras. Total 143 species of birds were recorded belonging to 15 orders and 41 families. Out of total 143 species 07 are migrant, 95 are Resident and 41 are Resident migrant. Seasonal variation is well marked in birds due to availability of food and nesting and suitable environmental conditions. Largest number (60) of bird species is recorded from order Passeriformes which belonging to 17 families.
18
Radach, R., D. Heller, P. Wiebories et W. Jaschinski. « Binocular Coordination, Fixation Disparity, and Ocular Dominance ». Perception 25, no 1_suppl (août 1996) : 128. http://dx.doi.org/10.1068/v96p0208.
Texte intégralRésumé :
In a series of experiments we have quantified the spatial and temporal dynamics of binocular coordination. Tasks studied ranged from simple scanning and letter detection to complex visual processing in text reading. In all of these paradigms we found similar eye movement characteristics: in 70% to 90% of the observations, the saccade of the abducting eye is larger, relative differences being in the order of 5% to 15% of the amplitude. During the subsequent fixation the disparity is typically reduced by a convergence movement (about 1 deg s−1), which sometimes exceeds the initial saccade amplitude asymmetry. Interestingly, the relative vergence contributions of the eyes depend on saccade length. For progressive 2-letter reading saccades, the left (adducting) eye accounts for only 20% of the total movement as compared to about 70% for 14-letter saccades. Up to now our analysis was limited to relative rather than absolute estimates of fixation disparity. To overcome this restriction, we measured disparity using the psychophysical method of dichoptically presented nonius lines as well as direct infrared pupil-reflection registration of binocular vs monocular fixation. Both measures were independent of target eccentricity (within a range typical for reading) and produced similar subject rank orders (Spearman's \rho=0.75). When we studied vergence movements in a letter detection task using autostereograms with different levels of virtual depth, it became clear that spatiotemporal vergence parameters can be quite asymmetric for both eyes. This led to the question of whether unequal contributions to vergence may be related to ocular dominance. This hypothesis is currently being investigated with a new procedure that provides a reliable estimate of subjective visual direction (the ‘cyclopean eye’) under static viewing conditions.
19
Pedani, Marco. « Sky Surface Brightness at Mount Graham : UBVRI Science Observations with the Large Binocular Telescope ». Publications of the Astronomical Society of the Pacific 121, no 881 (juillet 2009) : 778–86. http://dx.doi.org/10.1086/603605.
Texte intégral
20
Piggins, D., et C. J. C. Phillips. « The eye of the domesticated sheep with implications for vision ». Animal Science 62, no 2 (avril 1996) : 301–8. http://dx.doi.org/10.1017/s1357729800014612.
Texte intégralRésumé :
AbstractThe eyes of eighteen female sheep (Ovis aries) were refracted and details of inter ocular distance, pupil size, shape and fundus presence recorded. The sheep eyes generally possessed very low hyperopia with little astigmatism, such physiological optics being expected to produce a well focused retinal image for objects in the middle and long distance. No evidence was found for accommodation, which would have produced a well focused ocular image for near objects. A further 10 sheep had their monocular and binocular visual fields measured. The estimated visual field suggests the existence of at least binocular vision, if not the presence of stereopsis. Given the lack of accommodation and a wide inter-ocular distance, it is likely that some degree of stereopsis exists in the animal's middle and long distance vision, but is absent in near vision. These findings support those taken from the animal's neurophysiology and observations of its visually guided behaviour.
21
Aastrup, P., et A. Mosbech. « Transect width and missed observations in counting muskoxen (Ovibos moschatus) from fixed-wing aircraft ». Rangifer 13, no 3 (1 décembre 1993) : 99. http://dx.doi.org/10.7557/2.13.2.1096.
Texte intégralRésumé :
While conductioning muskox-censuses (Ovibos moschatus) in winter in Jameson Land, NE Greenland, from a fixed-wing aircraft, we examined the width of transects covered. We used a laser range-finder binocular for measuring the distance to observed groups. We found that 1000 m was a reasonable limit for observing a high proportion of the muskoxen present even though it was possible to observe muskoxen from 4000 m or even more. Using two observers on the right side of the aircraft each speaking into a tape recorder with an automatic time signal, we recorded observations and performed a double-observer experiment. By matching the group sizes and perpendicular distances with times of observation we could compare observations of the two observers. We found that both observers missed up to 25% of muskoxen within a 2000 m transect width. The main reasons for missing animals is difficulty in obtaining reference points in snow covered landscape and fatigue of the observers. Calibration of estimated distances using read-outs from the laser-range finder is an adequate method of obtaining distance data for line transect calculations. Our double-observer experiment demonstrated that even groups close to the transect are easily missed.
22
Vallely, P. J., M. A. Tucker, B. J. Shappee, J. S. Brown, K. Z. Stanek et C. S. Kochanek. « Signatures of bimodality in nebular phase Type Ia supernova spectra ». Monthly Notices of the Royal Astronomical Society 492, no 3 (10 janvier 2020) : 3553–65. http://dx.doi.org/10.1093/mnras/staa003.
Texte intégralRésumé :
ABSTRACT One observational prediction for Type Ia supernovae (SNe Ia) explosions produced through white dwarf–white dwarf collisions is the presence of bimodal velocity distributions for the 56Ni decay products, although this signature can also be produced by an off-centre ignition in a delayed detonation explosion. These bimodal velocity distributions can manifest as double-peaked or flat-topped spectral features in late-time spectroscopic observations for favourable viewing angles. We present nebular-phase spectroscopic observations of 17 SNe Ia obtained with the Large Binocular Telescope. Combining these observations with an extensive search of publicly available archival data, we collect a total sample of 48 SNe Ia and classify them based on whether they show compelling evidence for bimodal velocity profiles in three features associated with 56Ni decay products: the [Fe ii] and [Fe iii] feature at ∼5300 Å, the [Co iii] λ5891 feature, and the [Co iii] and [Fe ii] feature at ∼6600 Å. We identify nine bimodal SNe in our sample, and we find that these SNe have average peak MV about 0.3 mag fainter than those that do not. This is consistent with theoretical predictions for explosions created by nearly head-on collisions of white dwarfs due to viewing angle effects and 56Ni yields.
23
Howard, Ian P. « Alhazen's Neglected Discoveries of Visual Phenomena ». Perception 25, no 10 (octobre 1996) : 1203–17. http://dx.doi.org/10.1068/p251203.
Texte intégralRésumé :
The first three books of the Book of Optics written by Alhazen in Cairo in the eleventh century were translated into English by A I Sabra in 1989. Book I deals with optics, the structure of the eye, image formation in the eye, and with the visual pathways. This book inspired all other books on optics from the thirteenth to the seventeenth century and formed the basis upon which Kepler solved the problem of image formation. However, Alhazen's work contained in Books II and III has been almost totally ignored. These two books contain an account of hundreds of observations and experiments carried out by Alhazen on a broad range of topics which are now studied under the heading of visual perception. He clearly enunciated many of the fundamental principles which are credited to scientists living in the last two hundred years, including a theory of unconscious inference; the law of equal innervation of the eye muscles; the principles of binocular direction; constancy of size, shape, and colour; induced visual motion; the vertical horopter; the fusional range of binocular disparity; and many others.
24
Pedani, M. « Sky surface brightness at Mount Graham II. First JHKs science observations with the Large Binocular Telescope ». New Astronomy 28 (avril 2014) : 63–69. http://dx.doi.org/10.1016/j.newast.2013.10.005.
Texte intégral
25
Neilson, Peter, Megan Neilson et Robin Bye. « A Riemannian Geometry Theory of Three-Dimensional Binocular Visual Perception ». Vision 2, no 4 (5 décembre 2018) : 43. http://dx.doi.org/10.3390/vision2040043.
Texte intégralRésumé :
We present a Riemannian geometry theory to examine the systematically warped geometry of perceived visual space attributable to the size–distance relationship of retinal images associated with the optics of the human eye. Starting with the notion of a vector field of retinal image features over cortical hypercolumns endowed with a metric compatible with that size–distance relationship, we use Riemannian geometry to construct a place-encoded theory of spatial representation within the human visual system. The theory draws on the concepts of geodesic spray fields, covariant derivatives, geodesics, Christoffel symbols, curvature tensors, vector bundles and fibre bundles to produce a neurally-feasible geometric theory of visuospatial memory. The characteristics of perceived 3D visual space are examined by means of a series of simulations around the egocentre. Perceptions of size and shape are elucidated by the geometry as are the removal of occlusions and the generation of 3D images of objects. Predictions of the theory are compared with experimental observations in the literature. We hold that the variety of reported geometries is accounted for by cognitive perturbations of the invariant physically-determined geometry derived here. When combined with previous description of the Riemannian geometry of human movement this work promises to account for the non-linear dynamical invertible visual-proprioceptive maps and selection of task-compatible movement synergies required for the planning and execution of visuomotor tasks.
26
Karmali, Faisal, Stefano Ramat et Mark Shelhamer. « Vertical skew due to changes in gravitoinertial force : A possible consequence of otolith asymmetry ». Journal of Vestibular Research 16, no 3 (1 novembre 2006) : 117–25. http://dx.doi.org/10.3233/ves-2006-16304.
Texte intégralRésumé :
During the alternating enhanced and reduced "gravity" levels of parabolic flight, subjects noted that a horizontally eccentric point target viewed binocularly in darkness seemed to split into two targets with vertical divergence. The amount of perceived divergence seemed to depend on instantaneous g level. This perceptual observation suggested a vertical misalignment of the eyes (vertical skew), dependent on the magnitude of g level sensed by the otoliths. While performing a different experiment during parabolic flight we recorded binocular eye position and analyzed these data to corroborate the behavioral observations. Records were obtained from seven trials in five subjects, containing eye alignment in both 0 g and 1.8 g. The recordings confirm the presence of vertical skew that changed with g level. "Skew-differential" was quantified for each trial as the difference in vertical skew from 0 g to 1.8 g. Mean skew-differential was 1.37°; the largest was 2.57°. Statistical significance was assessed using the student t-test and the more correct and stringent Generalized Estimating Equations (GEE). The observed skew is equivalent to a mild strabismus, which is known to result in diplopia. The underlying mechanism may be an asymmetry between the otolith organs on either side, which is centrally compensated in 1 g, but is inappropriately compensated in other gravitational fields. If equivalent amounts of vertical skew were to occur during changes in g level during dynamic phases of flight in high-performance aircraft or space shuttle reentry, the impact on visual fixation might be detrimental to piloting performance.
27
Yan, F., N. Espinoza, K. Molaverdikhani, Th Henning, L. Mancini, M. Mallonn, B. V. Rackham et al. « LBT transmission spectroscopy of HAT-P-12b ». Astronomy & ; Astrophysics 642 (octobre 2020) : A98. http://dx.doi.org/10.1051/0004-6361/201937265.
Texte intégralRésumé :
The hot sub-Saturn-mass exoplanet HAT-P-12b is an ideal target for transmission spectroscopy because of its inflated radius. We observed one transit of the planet with the multi-object double spectrograph (MODS) on the Large Binocular Telescope (LBT) with the binocular mode and obtained an atmosphere transmission spectrum with a wavelength coverage of ~0.4–0.9 μm. The spectrum is relatively flat and does not show any significant sodium or potassium absorption features. Our result is consistent with the revised Hubble Space Telescope (HST) transmission spectrum of a previous work, except that the HST result indicates a tentative detection of potassium. The potassium discrepancy could be the result of statistical fluctuation of the HST dataset. We fit the planetary transmission spectrum with an extensive grid of cloudy models and confirm the presence of high-altitude clouds in the planetary atmosphere. The fit was performed on the combined LBT and HST spectrum, which has an overall wavelength range of 0.4–1.6 μm. The LBT/MODS spectrograph has unique advantages in transmission spectroscopy observations because it can cover a wide wavelength range with a single exposure and acquire two sets of independent spectra simultaneously.
28
Izotov, Y. I., T. X. Thuan et N. G. Guseva. « Large binocular telescope observations of new six compact star-forming galaxies with [Ne v] λ3426 Å emission ». Monthly Notices of the Royal Astronomical Society 508, no 2 (2 octobre 2021) : 2556–74. http://dx.doi.org/10.1093/mnras/stab2798.
Texte intégralRésumé :
ABSTRACT We report the discovery of [Ne v] λ3426 emission, in addition to He ii λ4686 emission, in six compact star-forming galaxies. These observations considerably increase the sample of eight such galaxies discovered earlier by our group. For four of the new galaxies, the optical observations are supplemented by near-infrared spectra. All galaxies, but one, have H ii regions that are dense, with electron number densities of ∼ 300–700 cm−3. They are all characterized by high H β equivalent widths EW(H β) ∼ 190–520 Å and high O32 = [O iii] λ5007/[O ii] λ3727 ratios of 10–30, indicating young starburst ages and the presence of high ionization radiation. All are low-metallicity objects with 12 + logO/H = 7.46–7.88. The spectra of all galaxies show a low-intensity broad component of the H α line and five of six objects show Wolf–Rayet features. Comparison with photoionization models shows that pure stellar ionization radiation from massive stars is not hard enough to produce such strong [Ne v] and He ii emission in our galaxies. The [Ne v] λ3426/He ii λ4686 flux ratio of ∼1.2 in J1222+3602 is consistent with some contribution of active galactic nucleus ionizing radiation. However, in the remaining five galaxies, this ratio is considerably lower, $\lesssim$ 0.4. The most plausible models are likely to be non-uniform in density, where He ii and [Ne v] lines are emitted in low-density channels made by outflows and illuminated by harder ionizing radiation from radiative shocks propagating through these channels, whereas [O iii] emission originates in denser regions exposed to softer stellar ionizing sources.
29
Jayadevan, Vijai, Tadamasa Sawada, Edward Delp et Zygmunt Pizlo. « Perception of 3D Symmetrical and Nearly Symmetrical Shapes ». Symmetry 10, no 8 (16 août 2018) : 344. http://dx.doi.org/10.3390/sym10080344.
Texte intégralRésumé :
The human visual system uses priors to convert an ill-posed inverse problem of 3D shape recovery into a well-posed one. In previous studies, we have demonstrated the use of priors like symmetry, compactness and minimal surface in the perception of 3D symmetric shapes. We also showed that binocular perception of symmetric shapes can be well modeled by the above-mentioned priors and binocular depth order information. In this study, which used a shape-matching task, we show that these priors can also be used to model perception of near-symmetrical shapes. Our near-symmetrical shapes are asymmetrical shapes obtained from affine distortions of symmetrical shapes. We found that the perception of symmetrical shapes is closer to veridical than the perception of asymmetrical shapes is. We introduce a metric to measure asymmetry of abstract polyhedral shapes, and a similar metric to measure shape dissimilarity between two polyhedral shapes. We report some key observations obtained by analyzing the data from the experiment. A website was developed with all the shapes used in the experiment, along with the shapes recovered by the subject and the shapes recovered by the model. This website provides a qualitative analysis of the effectiveness of the model and also helps demonstrate the goodness of the shape metric.
30
Hildreth, Ellen C. « Computational studies of the extraction of visual spatial information from binocular and motion cues ». Canadian Journal of Physiology and Pharmacology 66, no 4 (1 avril 1988) : 464–77. http://dx.doi.org/10.1139/y88-076.
Texte intégralRésumé :
This paper reviews some of the contributions that work in computational vision has made to the study of biological vision systems. We concentrate on two areas where there has been strong interaction between computational and experimental studies: the use of binocular stereo to recover the distances to surfaces in space, and the recovery of the three-dimensional shape of objects from relative motion in the image. With regard to stereo, we consider models proposed for solving the stereo correspondence problem, focussing on the way in which physical properties of the world constrain possible methods of solution. We also show how critical observations regarding human stereo vision have helped to shape these models. With regard to the recovery of structure from motion, we focus on how the constraint of object rigidity has been used in computational models of this process.
31
Raczkowski, D., D. J. Uhlrich et S. M. Sherman. « Morphology of retinogeniculate X and Y axon arbors in cats raised with binocular lid suture ». Journal of Neurophysiology 60, no 6 (1 décembre 1988) : 2152–67. http://dx.doi.org/10.1152/jn.1988.60.6.2152.
Texte intégralRésumé :
1. We examined the terminal arbors of single, physiologically identified retinogeniculate X and Y axons in 13 adult cats raised from birth with binocular lid suture. We recorded in the optic tract from 146 retinogeniculate axons. We studied the response properties of each axon encountered and attempted to penetrate it for labeling with horseradish peroxidase. 2. We attempted to classify each retinogeniculate axon as X or Y on a standard battery of tests. We thus identified 46 X and 91 Y axons; 5 axons had unusual response properties, and 4 axons were lost before they could be adequately identified. The X and Y axons had response properties that were completely normal by our criteria. The 5 unusual axons exhibited linear spatial and temporal summation, which is a property of X cells, despite all of their other tested response properties being consistent with those of Y cells. 3. We achieved complete, dark labeling of 13 X and 13 Y axons that form the data base for all of our qualitative and quantitative morphological observations. All of these labeled axons had response properties entirely normal for their X or Y class. Nine of the labeled X axons arise from the contralateral retina and 4 from the ipsilateral retina, whereas the respective numbers for the Y axons are 8 and 5. 4. Each of the individual retinogeniculate X axons form terminal arbors that appeared essentially normal in terms of location within geniculate lamina A or A1, shape, volume, and number of terminal boutons. 5. In contrast, the retinogeniculate Y axons form clearly abnormal arbors with diminished projections, both in terms of bouton numbers and arbor volumes. For Y axons from the contralateral retina, a roughly normal arbor is formed in the C-laminae, despite greatly diminished or absent projections formed in lamina A, something never seen in normal cats. For Y axons from the ipsilateral retina, the projections to lamina A1 are also diminished, and the arbors there are all limited to the ventral half of the lamina, a pattern rarely seen for normal Y axons. 6. The selective reduction in retinogeniculate Y axon arbors in these binocularly lid-sutured cats is consistent with similar observations reported for monocularly lid-sutured and strabismic cats but is quite different from the apparently normal development of retinogeniculate axon arbors in cats raised in complete darkness.(ABSTRACT TRUNCATED AT 400 WORDS)
32
Dave, Sanjev, J. K. Manchanda, Sameer Manchanda, Sheena Manchanda et Chitra Rekha. « Eye ball deviation patterns in traumatic cataract among children in Uttar Pradesh of India ». Indian Journal of Clinical and Experimental Ophthalmology 8, no 3 (15 octobre 2022) : 403–8. http://dx.doi.org/10.18231/j.ijceo.2022.082.
Texte intégralRésumé :
Paediatric cataract is an important cause of treatable childhood blindness, provided it is recognized and managed early. Timely diagnosis, management, and visual rehabilitation of a child with a paediatric cataract are crucial determinants of a favourable prognosis. This particular topic, study of pattern of deviation of eye ball after traumatic cataract in children was selected because of the difference between the firm literature of Keith Lyle and the clinical observations. This study includes analysis of 25 patients. The key findings of this study were: Maximum incidence of traumatic cataract was seen in 6-10 years of age group, that too more commonly in boys and it was 2.5 times more than that of girls. lncidence of perforating injuries leading to cataract was 1.5 times more common than blunt trauma. In paediatrics cataract, the Diminution of vision in cases of traumatic cataract is usually at the level of mature or hypermature cataract. 40% of cases showed deviation in the range of 11-20° (irrespective to divergence or convergence). There was higher incidence of Exotropia than esotropia. Originally eye was divergent as per evolution of binocular vision in primates & our study also came out with a conclusion that when there is no force or compulsion of binocular Vision, most of the eyes tended to be Divergent in children after traumatic cataract.
33
Rabien, S., R. Angel, L. Barl, U. Beckmann, L. Busoni, S. Belli, M. Bonaglia et al. « ARGOS at the LBT ». Astronomy & ; Astrophysics 621 (19 décembre 2018) : A4. http://dx.doi.org/10.1051/0004-6361/201833716.
Texte intégralRésumé :
Having completed its commissioning phase, the Advanced Rayleigh guided Ground-layer adaptive Optics System (ARGOS) facility is coming online for scientific observations at the Large Binocular Telescope (LBT). With six Rayleigh laser guide stars in two constellations and the corresponding wavefront sensing, ARGOS corrects the ground-layer distortions for both LBT 8.4 m eyes with their adaptive secondary mirrors. Under regular observing conditions, this set-up delivers a point spread function (PSF) size reduction by a factor of 2–3 compared to a seeing-limited operation. With the two LUCI infrared imaging and multi-object spectroscopy instruments receiving the corrected images, observations in the near-infrared can be performed at high spatial and spectral resolution. We discuss the final ARGOS technical set-up and the adaptive optics performance. We show that imaging cases with ground-layer adaptive optics (GLAO) are enhancing several scientific programmes, from cluster colour magnitude diagrams and Milky Way embedded star formation, to nuclei of nearby galaxies or extragalactic lensing fields. In the unique combination of ARGOS with the multi-object near-infrared spectroscopy available in LUCI over a 4 × 4 arcmin field of view, the first scientific observations have been performed on local and high-z objects. Those high spatial and spectral resolution observations demonstrate the capabilities now at hand with ARGOS at the LBT.
34
Riesenhuber, M., H. U. Bauer, D. Brockmann et T. Geisel. « Breaking Rotational Symmetry in a Self-Organizing Map Model for Orientation Map Development ». Neural Computation 10, no 3 (1 avril 1998) : 717–30. http://dx.doi.org/10.1162/089976698300017719.
Texte intégralRésumé :
We analyze the pattern formation behavior of a high-dimensional self-organizing map (SOM) model for the competitive projection of ON-center-type and OFF-center-type inputs to a common map layer. We mathematically show, and numerically confirm, that even isotropic stimuli can drive the development of oriented receptive fields and an orientation map in this model. This result provides an important missing link in the spectrum of pattern formation behaviors observed in SOM models. Extending the model by including further layers for binocular inputs, we also investigate the combined development of orientation and ocular dominance maps. A parameter region for combined patterns exists; corresponding maps show a preference for perpendicular intersection angles between iso-orientation lines and ocularity domain boundaries, consistent with experimental observations.
35
Zanandréa, Ledilma Inês Duarte Colodetti, Gabriela Mantovanelli Oliveira, Andressa Silva Abreu et Fausto Edmundo Lima Pereira. « Ocular lesions in gerbils (Meriones unguiculatus) infected with low larval burden of Toxocara canis : observations using indirect binocular ophthalmoscopy ». Revista da Sociedade Brasileira de Medicina Tropical 41, no 6 (décembre 2008) : 570–74. http://dx.doi.org/10.1590/s0037-86822008000600005.
Texte intégralRésumé :
To study the frequency of ocular lesions in 30 gerbils infected with 100 embryonated eggs of Toxocara canis, indirect binocular ophthalmoscopy was performed 3, 10, 17, 24, 31 and 38 days after infection. All the animals presented larvae in the tissues and 80% presented ocular lesions. Hemorrhagic foci in the choroid and retina were present in 92% of the animals with ocular lesions. Retinal exudative lesions, vitreous lesions, vasculitis and retinal detachment were less frequent. Mobile larvae or larval tracks were observed in four (13.3%) animals. Histological examination confirmed the ophthalmoscopic observations, showing that the lesions were focal and sparse. In one animal, there was a larva in the retina, without inflammatory reaction around it. The results demonstrated that gerbils presented frequent ocular lesions after infection with Toxocara canis, even when infected with a small number of embryonated eggs. The lesions observed were focal, consisting mainly of hemorrhages with signs of reabsorption or inflammation in different segments of eye, and differing from the granulomatous lesions described in ocular larva migrans in humans.
36
READ, JENNY C. A., ANDREW J. PARKER et BRUCE G. CUMMING. « A simple model accounts for the response of disparity-tuned V1 neurons to anticorrelated images ». Visual Neuroscience 19, no 6 (novembre 2002) : 735–53. http://dx.doi.org/10.1017/s0952523802196052.
Texte intégralRésumé :
Disparity-tuned cells in primary visual cortex (V1) are thought to play a significant role in the processing of stereoscopic depth. The disparity-specific responses of these neurons have been previously described by an energy model based on local, feedforward interactions. This model fails to predict the response to binocularly anticorrelated stimuli, in which images presented to left and right eyes have opposite contrasts. The original energy model predicts that anticorrelation should invert the disparity tuning curve (phase difference π), with no change in the amplitude of the response. Experimentally, the amplitude tends to be reduced with anticorrelated stimuli and a spread of phase differences is observed, although phase differences near π are the most common. These experimental observations could potentially reflect a modulation of the V1 signals by feedback from higher visual areas (because anticorrelated stimuli create a weaker or nonexistent stereoscopic depth sensation). This hypothesis could explain the effects on amplitude, but the spread of phase differences is harder to understand. Here, we demonstrate that changes in both amplitude and phase can be explained by a straightforward modification of the energy model that involves only local processing. Input from each eye is passed through a monocular simple cell, incorporating a threshold, before being combined at a binocular simple cell that feeds into the energy computation. Since this local feedforward model can explain the responses of complex cells to both correlated and anticorrelated stimuli, there is no need to invoke any influence of global stereoscopic matching.
37
Yuliana, Ida, Triawanti Triawanti, Didik Dwi Sanyoto, Husnul Khatimah, Asnawati Asnawati et Rayatul Aminah. « The Potential of Pasak Bumi as a Food Supplement to Improve Spermatogenesis in Mice Model of Malnutrition ». Jurnal Berkala Kesehatan 7, no 1 (31 mai 2021) : 65. http://dx.doi.org/10.20527/jbk.v7i1.10526.
Texte intégralRésumé :
Malnutrition causes disruption of spermatogenesis in children. Pasak Bumi has the potential to increase spermatogenesis due to malnutrition. Aimed of research is to proved Pasak Bumi as a food supplement to improve spermatogenesis disorders due to malnutrition in malnourished rats. The research method used analytical observational method by observing the histological preparations of the testes of malnourished rats. Observations using a binocular microscope were analyzed with Optilab Camera and Image Raster software. There are 5 groups of experimental: M: malnutrition without intervention; P1: malnutrition + standard feed + PB 7.5 mg/kgBW; P2: malnutrition + standard feed + PB 15 mg/kgBW; P3: malnutrition + standard feed + PB 22.5 mg/kgBW; P4: malnutrition + standard feed + PB 30 mg/kgBW; Research parameters were number of seminiferous tubules, primary spermatocytes and Leydig cells. Data analysis used the Anova One way test with a confidence level of 95%. The results showed number of seminiferous tubules, primary spermatocytes and Leydig cells in the M group was less than the P1-P4 group. This suggests malnutrition causes disruption of spermatogenesis. Conclusion the administration of Pasak Bumi extract at various doses increased spermatogenesis in malnourished.
38
Keles, Engin, Matthias Mallonn, Carolina von Essen, Thorsten A. Carroll, Xanthippi Alexoudi, Lorenzo Pino, Ilya Ilyin et al. « The potassium absorption on HD189733b and HD209458b ». Monthly Notices of the Royal Astronomical Society : Letters 489, no 1 (12 août 2019) : L37—L41. http://dx.doi.org/10.1093/mnrasl/slz123.
Texte intégralRésumé :
ABSTRACT In this work, we investigate the potassium excess absorption around 7699 Å of the exoplanets HD189733b and HD209458b. For this purpose, we used high-spectral resolution transit observations acquired with the 2 × 8.4 m Large Binocular Telescope (LBT) and the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI). For a bandwidth of 0.8 Å, we present a detection >7σ with an absorption level of 0.18 per cent for HD189733b. Applying the same analysis to HD209458b, we can set 3σ upper limit of 0.09 per cent, even though we do not detect a K-excess absorption. The investigation suggests that the K feature is less present in the atmosphere of HD209458b than in the one of HD189733b. This comparison confirms previous claims that the atmospheres of these two planets must have fundamentally different properties.
39
Pilo, S., M. Castellano, A. Fontana, A. Grazian, K. Boutsia, L. Pentericci, E. Giallongo, E. Merlin, D. Paris et P. Santini. « UV slope of z ∼ 3 bright (L > ; L*) Lyman-break galaxies in the COSMOS field ». Astronomy & ; Astrophysics 626 (juin 2019) : A45. http://dx.doi.org/10.1051/0004-6361/201834442.
Texte intégralRésumé :
Context. The analysis of the UV slope β of Lyman-break galaxies (LBG) at different luminosities and redshifts is fundamental for understanding their physical properties, and in particular, their dust extinction. Aims. We analyse a unique sample of 517 bright (L > L*) LBGs at redshift z ∼ 3 in order to characterise the distribution of their UV slopes β and infer their dust extinction under standard assumptions. Methods. We exploited multi-band observations over 750 arcmin2 of the COSMOS field that were acquired with three different ground-based facilities: the Large Binocular Camera (LBC) on the Large Binocular Telescope (LBT), the Suprime-Cam on the SUBARU telescope, and the VIRCAM on the VISTA telescope (ULTRAVISTA DR2). Our multi-band photometric catalogue is based on a new method that is designed to maximise the signal-to-noise ratio in the estimate of accurate galaxy colours from images with different point spread functions (PSF). We adopted an improved selection criterion based on deep Y-band data to isolate a sample of galaxies at z ∼ 3 to minimise selection biases. We measured the UV slopes (β) of the objects in our sample and then recovered the intrinsic probability density function of β values (PDF(β)), taking into account the effect of observational uncertainties through detailed simulations. Results. The galaxies in our sample are characterised by mildly red UV slopes with ⟨β⟩≃ − 1.70 throughout the enitre luminosity range that is probed by our data (−24 ≲ M1600 ≲ −21). The resulting dust-corrected star formation rate density (SFRD) is log(SFRD)≃ − 1.6 M⊙ yr−1 Mpc−3, corresponding to a contribution of about 25% to the total SFRD at z ∼ 3 under standard assumptions. Conclusions. Ultra-bright LBGs at z ∼ 3 match the known trends, with UV slopes being redder at decreasing redshifts, and brighter galaxies being more highly dust extinct and more frequently star-forming than fainter galaxies.
40
Toh, Y., et J. Y. Okamura. « Behavioural responses of the tiger beetle larva to moving objects : role of binocular and monocular vision ». Journal of Experimental Biology 204, no 4 (15 février 2001) : 615–25. http://dx.doi.org/10.1242/jeb.204.4.615.
Texte intégralRésumé :
The larva of the tiger beetle Cicindela chinensis is an ambushing hunter with a body length of 15–22 mm that lives in a tunnel in the ground. It ambushes prey, keeping its head horizontal at the opening of the tunnel. When prey approaches the tunnel, the larva jumps to snap at it. When an object moves beyond its jumping range (approximately 15 mm), however, the larva quickly withdraws deep into the tunnel. These responses are mediated by two of six pairs of stemmata. How does the larva judge the hunting range using such a simple visual system? A previous study suggested that both binocular and monocular vision are used for distance estimation. Range estimation by binocular vision was further confirmed in the present behavioural observations: larvae jumped towards objects beyond the normal hunting range when virtual images of such distant objects were formed close to the larva using prisms or a narrow window. A possible mechanism involved in range estimation by monocular vision was also examined in behavioural experiments. The depth of the image in the retina appears to play a role in distance estimation because a larva with one functional stemma, the other stemmata being occluded, changed its response to a very distant object from an escape to a predatory jump when a concave lens was placed above its head. Two alternative ideas, based on optical and morphological data, are proposed to explain this behavioural change by the one-stemma larvae. First, as for myopic people, the larva might see clearly only objects that are close. Second, an infinitely distant object might produce a focused image only on the central part of the retina, whereas an object within hunting range (<15 mm) might do so on surrounding regions of the retina. The latter idea implies that the region of the retina at which the larva perceives a clear image is concerned with which type of behaviour is released, a predatory jump or an escape. We conclude that visual information about hunting range in the tiger beetle larva is extracted both peripherally by the spatial pattern of image clarity and centrally by binocular vision.
41
Belladitta, S., A. Caccianiga, A. Diana, A. Moretti, P. Severgnini, M. Pedani, L. P. Cassarà et al. « Central engine of the highest redshift blazar ». Astronomy & ; Astrophysics 660 (avril 2022) : A74. http://dx.doi.org/10.1051/0004-6361/202142335.
Texte intégralRésumé :
We present the results of a new LUCI/Large Binocular Telescope near-infrared (NIR) spectroscopic observation of PSO J030947.49+271757.31 (hereafter PSO J0309+27), the highest redshift blazar known to date (z ∼ 6.1). From the CIV λ1549 broad emission line, we found that PSO J0309+27 is powered by a 1.45−0.85+1.89 × 109 M⊙ supermassive black hole (SMBH) with a bolometric luminosity of ∼8 × 1046 erg s−1 and an Eddington ratio equal to 0.44−0.35+0.78. We also obtained new photometric observations with the Telescopio Nazionale Galileo in J and K bands to better constrain the NIR spectral energy distribution of the source. Thanks to these observations, we were able to model the accretion disk and to derive an independent estimate of the black hole mass of PSO J0309+27, confirming the value inferred from the virial technique. The existence of such a massive SMBH just ∼900 million years after the Big Bang challenges models of the earliest SMBH growth, especially if jetted active galactic nuclei are indeed associated with a highly spinning black hole, as is currently assumed. In a Eddington-limited accretion scenario and assuming a radiative efficiency of 0.3, typical of a fast rotating SMBH, a seed black hole of more than 106 M⊙ at z = 30 is indeed required to reproduce the mass of PSO J0309+27 at a redshift of 6. This requirement suggests either earlier periods of rapid black hole growth with super-Eddington accretion or a scenario in which only part of the released gravitational energy goes toward heating the accretion disk and feeding the black hole.
42
Wajer, S. D., et P. H. Cohen. « Fractographic Evaluation of Thermally Stressed Single Crystal Sapphire ». Microscopy and Microanalysis 4, S2 (juillet 1998) : 516–17. http://dx.doi.org/10.1017/s1431927600022704.
Texte intégralRésumé :
Optical, video and scanning electron microscopic observations show fractographic features that are used to determine the crack propagation direction and crack origin in thermally stressed single crystal sapphire hemispherical shells. These features have been typically identified in materials with symmetrically applied stresses and simple geometries. This fractographic evaluation of sapphire is unusual because of the hemispherical geometry and complex mechanical and thermal stress conditions. Computer models predict the thermal stress response of the sapphire from fast acting asymmetrical heating patterns generated during controlled laboratory testing. These experimental tests are conducted to validate the computer model predictions. When an experimental structure fails to meet the survival limits predicted by the computer model, a fractographic evaluation is conducted to determine fracture mode and to locate the crack initiation site.Fractured pieces are examined and photographed using a low magnification, binocular optical microscope and a high resolution video camera with digitizing capabilities.
43
Hubrig, S., S. P. Järvinen, I. Ilyin, K. G. Strassmeier et M. Schöller. « The rapidly oscillating Ap star γ Equ : linear polarization as an enhanced pulsation diagnostic ? » Monthly Notices of the Royal Astronomical Society : Letters 508, no 1 (24 août 2021) : L17—L21. http://dx.doi.org/10.1093/mnrasl/slab101.
Texte intégralRésumé :
ABSTRACT We present the first short time-scale observations of the rapidly oscillating Ap (roAp) star γ Equ in linear polarized light obtained with the Potsdam Echelle Polarimetric and Spectroscopic Instrument installed at the Large Binocular Telescope. These observations are used to search for pulsation variability in Stokes Q and U line profiles belonging to different elements. The atmospheres of roAp stars are significantly stratified with spectral lines of different elements probing different atmospheric depths. roAp stars with strong magnetic fields, such as γ Equ with a magnetic field modulus of 4 kG and a pulsation period of 12.21 min, are of special interest because the effect of the magnetic field on the structure of their atmospheres can be studied with greatest detail and accuracy. Our results show that we may detect changes in the transversal field component in Fe i and rare earth element lines possessing large second-order Landé factors. Such variability can be due to the impact of pulsation on the transverse magnetic field, causing changes in the obliquity angles of the magnetic force lines. Further studies of roAp stars in linear polarized light and subsequent detailed modelling are necessary to improve our understanding of the involved physics.
44
Deng, Licai, Yu Xin, Xiaobin Zhang, Yan Li, Xiaojun Jiang, Guomin Wang, Kun Wang, Jilin Zhou, Zhengzhou Yan et Zhiquan Luo. « SONG China project – participating in the global network ». Proceedings of the International Astronomical Union 8, S288 (août 2012) : 318–19. http://dx.doi.org/10.1017/s1743921312017115.
Texte intégralRésumé :
AbstractSONG (Stellar Observations Network Goup) is a low-cost ground based international collaboration aimed at two cutting edge problems in contemporary astrophysics in the time-domain: 1) Direct diagnostics of the internal structure of stars and 2) looking for and studying extra solar planets, possibly in the habitable zone. The general plan is to set up a network of 1m telescopes uniformly distributed in geographic latitude (in both hemispheres). China jointed the collaboration (initiated by Danish astronomers) at the very beginning. In addition to SONG's original plan (http://song.phys.au.dk), the Chinese team proposed a parallel photometry subnet work in the northern hemisphere, namely 50BiN (50cm Binocular Network, previously known as mini-SONG), to enable a large field photometric capability for the network, therefore maximising the potential of the network platform. The network will be able to produce nearly continuous time series observations of a number of selected objects with high resolution spectroscopy (SONG) and accurate photometry (50BiN), and to produce ultra-high accuracy photometry in dense field to look for micro-lensing events caused by planetary systems. This project has great synergy with Chinese Astronomical activities in Antarctica (Dome A), and other similar networks (e.g. LCOGT). The plan and current status of the project are overviewed in this poster.
45
Paige, G. D., et D. L. Tomko. « Eye movement responses to linear head motion in the squirrel monkey. II. Visual-vestibular interactions and kinematic considerations ». Journal of Neurophysiology 65, no 5 (1 mai 1991) : 1183–96. http://dx.doi.org/10.1152/jn.1991.65.5.1183.
Texte intégralRésumé :
1. Horizontal, vertical, and torsional eye movements were recorded (search coil technique) from five squirrel monkeys during horizontal linear oscillations at 0.5, 1.5, and 5.0 Hz, 0.36 g peak acceleration. Monkeys were positioned to produce linear motion in their nasooccipital (NO), interaural (IA), and dorsoventral (DV) axes. Responses of the linear vestibuloocular reflex (LVOR) were recorded in darkness and in the light with the subjects viewing a head-fixed field 22 or 9.2 cm from the eye. The latter condition provided a measure of "visual suppression" of the LVOR (VSLVOR). Responses were also recorded while monkeys viewed earth-fixed targets, which allowed visual enhancement of the LVOR (VLVOR). Vergence angle was recorded in two monkeys to assess directly the point of binocular fixation in space during linear motion. 2. Two LVOR response types, vertical responses during 0.5-Hz NO-axis translation (NO-vertical) and torsional responses at all frequencies during IA-axis oscillation (IA-torsional) could not be compensatory reflexes for head translation because they either move the eye off target (NO-vertical) or tort the eye relative to the visual world (IA-torsional), thereby degrading visual image stability. 3. Other response types are considered compensatory because they help maintain ocular fixation in space during linear head translation. These include horizontal responses to IA-axis motion (IA-horizontal), vertical responses to DV-axis translation (DV-vertical), and both horizontal and vertical responses to NO-axis oscillation (1.5 and 5 Hz). Observations focus on responses to 5-Hz oscillations, in which visual inputs are essentially ineffective in modifying the LVOR. 4. The kinematics of perfect ocular compensation during head translation indicate that the ideal ocular response is governed by the motion of the eye relative to target position. Relevant variables include target distance, which is crucial for all axes of motion, and target eccentricity, which is important only for head motion roughly parallel to the target (NO-axis translation). Findings are compatible with predictions based on ideal kinematics. However, it is the point of binocular fixation in space, not actual target position, that governs LVOR behavior. 5. The IA-horizontal and DV-vertical LVOR is in response to head motion roughly orthogonal to the line of sight. Responses under all stimulus conditions (LVOR, VSLVOR, and VLVOR) behaved similarly at 5 Hz, and were modulated linearly with vergence [in meter angles (MA), the reciprocal of binocular fixation distance].(ABSTRACT TRUNCATED AT 400 WORDS)
46
Dawkins, Marian Stamp. « How Do Hens View Other Hens ? the Use of Lateral and Binocular Visual Fields in Social Recognition ». Behaviour 132, no 7-8 (1995) : 591–606. http://dx.doi.org/10.1163/156853995x00225.
Texte intégralRésumé :
AbstractWhen shown familiar and unfamiliar birds at different distances, hens viewed birds 0.7 m or 1.4 m away with modal head angles between 54° and 72° from the midline, using the lateral visual field but viewed birds closer (less than 20 cm) binocularly, with the head within 18° either side of the midline (Expt. 1 When faced with a choice between a familiar and an unfamiliar bird at different distances, hens chose the familiar bird if the choice could be made 8 cm away but their choices were random if they had to chose 66 or 124 cm away (Expt. 2). This suggests that hens may be unable to discriminate familiar from unfamiliar birds except when they are very close to them. Observations of freely moving birds suddenly confronted with another hen (Expt. 3) showed that even when the object bird was familiar, it was in all cases initially scrutinized from a close distance (26 cm or less), which is consistent with the hypothesis that hens are unable to recognize other birds except when close enough to view them with the myopic lower frontal field. Reasons for this constraint on social recognition are discussed.
47
Hidayah, Alfi, Alif Nailil Muna AR, Agatha Yolanda Chirstanty et Muhammad Jafar Luthfi. « Anatomy of Trabeculae Lumbar Vertebrae On a Bats (Megachiroptera) ». Proceeding International Conference on Science and Engineering 3 (30 avril 2020) : 81–83. http://dx.doi.org/10.14421/icse.v3.473.
Texte intégralRésumé :
Bats are the only mammals that can fly. Because of their ability to fly, making the tension received by the bat's spine comes from the front and back.Spongy bone, also known as cancellous bone or trabecular bone, is a very porous type of bone found in animals. It is highly vascularized and contains red bone marrow. Spongy bone is usually located at the ends of the long bones (the epiphyses), with the harder compact bone surrounding it. It is also found inside the vertebrae, in the ribs, in the skull and in the bones of the joints. Spongy bone is softer and weaker than compact bone, but is also more flexible. It is characterized by a lattice-like matrix network called trabeculae (Latin for little beam) that gives it its spongy appearance. Observation of trabeculae can be done by removing the flesh, muscles, and all the tissues attached to the lumbar vertebrae bone. Then the lumbar vertebrae was sanded and to know the anatomy of the trabeculae, it was done by observing the lumbraris vertebrae using a binocular microscope and taking pictures using a camera. Then the structure is analyzed. The observations showed that the anatomical structure of the lumbar vertebrae trabeculae in bats are stressed by tension must be withstood, a ligament being as strong for its weight.
48
Hamilton, Timothy S., Marco Berton, Sonia Antón, Lorenzo Busoni, Alessandro Caccianiga, Stefano Ciroi, Wolfgang Gässler et al. « Observations of the γ-ray-emitting narrow-line Seyfert 1, SBS 0846+513, and its host galaxy ». Monthly Notices of the Royal Astronomical Society 504, no 4 (16 avril 2021) : 5188–98. http://dx.doi.org/10.1093/mnras/stab1046.
Texte intégralRésumé :
ABSTRACT The γ-ray-emitting galaxy SBS 0846+513 has been classified as a narrow-line Seyfert 1 (NLS1) from its spectroscopy, and on that basis would be thought likely to have a small central black hole hosted in a spiral galaxy. However, very few of the γ-ray NLS1s have high-resolution imaging of their hosts, so it is unknown how the morphology expectation holds up for the γ-emitting class. We have observed this galaxy in the J band with the Large Binocular Telescope’s LUCI1 camera and the ARGOS adaptive optics system. We estimate its black hole mass to lie between $4.2\times 10^7 \le \frac{\rm{\it{ M}}}{\text{M}_\odot } \le 9.7\times 10^7$, using the correlation with bulge luminosity, or $1.9\times 10^7 \le \frac{\rm{\it{ M}}}{\text{M}_\odot } \le 2.4\times 10^7$ using the correlation with Sérsic index. Our favoured estimate is 4.2 × 107 M⊙, putting its mass at the high end of the NLS1 range in general but consistent with others that are γ-ray emitters. These estimates are independent of the broad-line region viewing geometry and avoid any underestimates due to looking down the jet axis. Its host shows evidence of a bulge + disc structure, from the isophote shape and residual structure in the nuclear-subtracted image. This supports the idea that γ-ray NLS1 may be spiral galaxies, like their non-jetted counterparts.
49
Munin, RL, E. Fischer et JM Longo. « Foraging of Great Kiskadees (Pitangus sulphuratus) and food items offered to nestlings in the Pantanal ». Brazilian Journal of Biology 72, no 3 (août 2012) : 459–62. http://dx.doi.org/10.1590/s1519-69842012000300007.
Texte intégralRésumé :
Feeding of Pitangus sulphuratus (Tyrannidae) nestlings have been poorly studied. Here we describe the foraging behavior of a P. sulphuratus pair and the searching and offering time of food items to nestlings in the Pantanal, Brazil. Data collection was carried out over 25 days on the outskirts of the Base de Estudos do Pantanal building, inhabited by insectivorous bats. Records were based on direct observations with the help of binocular. The pair required little time for searching for small insects and fruits, but these items comprised a little amount of food per event of capture. Some large prey was more time-costly for searching, but the long period that these food items were offered to nestlings overcompensated the searching time. Considering the time of feeding nestlings (benefit) in relation to the searching time by the parents (cost), bats and snails are the most advantageous items for P. sulphuratus parents feeding nestlings at the study site.
50
Doelman, David S., Jordan M. Stone, Zackery W. Briesemeister, Andrew J. I. Skemer, Travis Barman, Laci S. Brock, Philip M. Hinz et al. « L-band Integral Field Spectroscopy of the HR 8799 Planetary System ». Astronomical Journal 163, no 5 (19 avril 2022) : 217. http://dx.doi.org/10.3847/1538-3881/ac5d52.
Texte intégralRésumé :
Abstract Understanding the physical processes sculpting the appearance of young gas-giant planets is complicated by degeneracies confounding effective temperature, surface gravity, cloudiness, and chemistry. To enable more detailed studies, spectroscopic observations covering a wide range of wavelengths are required. Here we present the first L-band spectroscopic observations of HR 8799 d and e and the first low-resolution wide-bandwidth L-band spectroscopic measurements of HR 8799 c. These measurements were facilitated by an upgraded LMIRCam/ALES instrument at the Large Binocular Telescope, together with a new apodizing phase plate coronagraph. Our data are generally consistent with previous photometric observations covering similar wavelengths, yet there exists some tension with narrowband photometry for HR 8799 c. With the addition of our spectra, each of the three innermost observed planets in the HR 8799 system has had its spectral energy distribution measured with integral field spectroscopy covering ∼0.9–4.1 μm. We combine these spectra with measurements from the literature and fit synthetic model atmospheres. We demonstrate that the bolometric luminosity of the planets is not sensitive to the choice of model atmosphere used to interpolate between measurements and extrapolate beyond them. Combining luminosity with age and mass constraints, we show that the predictions of evolutionary models are narrowly peaked for effective temperature, surface gravity, and planetary radius. By holding these parameters at their predicted values, we show that more flexible cloud models can provide good fits to the data while being consistent with the expectations of evolutionary models.