scholarly journals When Is Accreting/Deleting Texture Seen as In Front? Interpretation of Depth From Texture Motion

Perception ◽  
2018 ◽  
Vol 47 (7) ◽  
pp. 694-721
Author(s):  
Ömer Dağlar Tanrıkulu ◽  
Vicky Froyen ◽  
Jacob Feldman ◽  
Manish Singh
Keyword(s):  
Critical Factor ◽  
Number Of Factors ◽  
Series Of Experiments ◽  
Occluding Contour ◽  
Depth Ordering

Standard accounts of accretion/deletion of texture treat it as a definite cue to depth ordering: The accreting/deleting surface is interpreted as being behind the adjoining surface. Froyen, Feldman, and Singh showed that accretion/deletion can also, under certain circumstances, be perceived as a 3D column rotating in front, with the accretion/deletion explained by self-occlusion. These displays differ from traditional accretion/deletion displays in a number of factors, including the presence of figure/ground cues, accretion/deletion on both sides of boundaries, and in the number of distinct regions. In a series of experiments, we systematically manipulated each of these factors in order to determine what factors are actually instrumental in creating the rotating column (accretion/deletion in front) interpretation. In Experiment 1, the width of each region was kept fixed while manipulating the number of regions, and in Experiment 2, the width of the overall display was kept fixed. Observers indicated which set of regions they perceived to be in front. In both experiments, accreting/deleting regions were most likely to be seen in front when geometric figural cues favored a figural interpretation and when textural motion was introduced in all regions (rather than on just one side of each boundary). The number of regions had a relatively small effect (although this effect was larger in Experiment 2). These findings indicate that the geometry of the occluding contour is a critical factor in the interpretation of accretion/deleting, and future models of 3D interpretation involving accretion/deletion must include contour geometry as a key component.

scholarly journals Multiplication végétative de Dacryodes edulis (G. Don) H.J. Lam. par marcottage aérien

Afrika Focus ◽  
1970 ◽  
Vol 27 (3) ◽  
Author(s):  
Christiane Elomo ◽  
Blandine Nguénayé ◽  
Zacharie Tchoundjeu ◽  
Ebenezar Assah ◽  
Alain Tsobeng ◽  
...  
Keyword(s):  
Central Africa ◽  
Orientation Factor ◽  
Primary Roots ◽  
Number Of Factors ◽  
West And Central Africa ◽  
Series Of Experiments ◽  
The Mean ◽  
Best Parameters ◽  
Dacryodes Edulis ◽  
Plum Tree

Dacryodes edulis (G. Don) H. J. Lam. (Burseraceae) is a high-value fruit tree in West and Central Africa. Air layering of this species is now under control, but uncertainty remains as to the effect of a number of factors on rooting; these include cloning the type of propagule, the orientation of branches and the position of the marcots in the crown. A series of experiments were conducted to evaluate the effect of cloning, the type of propagule (cuttings and marcots), position in the crown (lower and upper) and the orientation of branches (plagiotropic, oblic and orthotropic) on the tree ́s rooting ability. For the frst three factors, older clones of 10 years with a normal maturation were bedded in equal proportions of decomposed sawdust and arable soil. To test the orientation factor late maturing trees of over 20 years bedded in, decomposed sawdust were used. Ten months after the setting up of marcots, the results showed that the clonal effect significantly (p<0.001) af- fects the rooting of marcots. The best result was obtained for clones MA/DE/40M, BUM/DE/36M and DE/M/2-70C. The type of propagule had a significant effect (p<0.012) on percentage of rooting marcots. On the dead marcots, this effect was significant (p<0.038) from the eighth month. No significant effect (p = 0.124) of the position of the branch in the crown was recorded on the rooting of marcots. However, the upper crown had apparently a high percentage of rooting (39.59 ± 3.37%) compared to that of the lower crown (31.94 ± 3.44%) at 10 months. The percentage of dead marcots recorded was high at lower crown marcots (40.28 ± 4.08%) and the mean number of primary roots was low (6.97 ± 0.87 %) compared to the upper part (33.33 ± 3.91 and 7.36 ± 0.8% respectively). Nine months after the setting up of marcots, the orthotropic branches showed a high number of primary roots (13.55 ± 1.22%) and a low percentage of dead marcots (6.67 ± 4.55%) compared to plagiotropic branches (7.84 ± 0.77 and 26.67 ± 8.05% respectively). With respect to the orientation of branches, no significant (p = 0.45) effect on the rooting of marcots was recorded, but the rooting percentage of marcots on plagiotropic and oblic branches (43.33 ± 9.05%) was high compared to the percentage of orthotropic branch (30 ± 8.34%). It can therefore be concluded from this study that orthotropic branches of D. edulis, upper crown are among the best parameters for air layering. Key words: domestication, African plum tree, clone, marcots, Cameroon 

scholarly journals Usefulness of Apogee® for the PA Apple Industry

HortScience ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 828C-828
Author(s):  
George M. Greene
Keyword(s):  
Shoot Growth ◽  
Growth Control ◽  
Critical Factor ◽  
Apple Industry ◽  
Initial Application ◽  
Production Problem ◽  
Series Of Experiments ◽  
Terminal Shoot ◽  
Major Factors ◽  
Significant Production

Excessive tree vigor is a significant production problem for the PA apple industry. A series of experiments were conducted from 1994 to 1999, which indicated that Apogee® could effectively reduce vegetative shoot growth. Results from 1994 to 1996 have previously been reported (HortScience 31:598, 32:558). In 1997, 16 treatments composed of four rates (0, 63, 125, and 250 ppm) and four timings (22 May; 4, 11, and 24 June) in various combinations, were applied as dilute handgun sprays. These treatments were applied to sixth leaf `York Imperial' apple trees. Ten peripheral shoots, at a height of 2 m, were tagged and measured on 21 May, 9 and 30 June, 16 July, 12 Aug., and on 10 Oct. Shoots treated with 63, 125, or 250 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June were from 65% to 76% of the length of the controls (25.5 cm). Treated shoots were from 69% to 78% of the length of the controls following sprays with 63 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June. Shoots treated with 125 ppm on 22 May followed by 0 or 63 ppm on 4, 11, or 24 June were from 69% to 73% of the length of the controls. The later applications (11 and 24 June) of 250 ppm gave no growth control but the 22 May treatment gave a 30% reduction in growth. In 1999, dilute handgun sprays of 125, 125, 83, and 83 ppm were made on 22 May and on 4, 11, and 24 June, respectively. Cultivars treated were `Spartan', `Delicious', `York Imperial', `Gala', and `Mutsu'. The length of 10 peripheral shoots at 2 and 3 m were measured on 28 July and on 12 Aug. All cultivars responded and on 12 Aug. treated terminal shoot lengths ranged from 33% to 55% of the controls. With reduced vegetative tree vigor many horticultural factors will be improved. In addition, the severity of shoot fire blight can be reduced and the control of all pests that prosper on young succulent leaves will be easier, especially apple aphids and obliquebanded leafrollers. Major factors to be considered in developing an efficacious Apogee® program appear to be initial tree vigor, length of growing season, and crop load. An initial application at 1 to 3 inches of terminal growth is probably the most critical factor.

scholarly journals Blur Discrimination and its Relation to Blur-Mediated Depth Perception

Perception ◽  
10.1068/p3254 ◽  
2002 ◽  
Vol 31 (10) ◽  
pp. 1211-1219 ◽  
Author(s):  
George Mather ◽  
David R R Smith
Keyword(s):  
Depth Perception ◽  
Three Dimensional ◽  
The Other ◽  
Retinal Images ◽  
Apparent Depth ◽  
Depth Of Focus ◽  
Depth Cue ◽  
Series Of Experiments ◽  
Different Levels ◽  
Depth Ordering

Retinal images of three-dimensional scenes often contain regions that are spatially blurred by different amounts, owing to depth variation in the scene and depth-of-focus limitations in the eye. Variations in blur between regions in the retinal image therefore offer a cue to their relative physical depths. In the first experiment we investigated apparent depth ordering in images containing two regions of random texture separated by a vertical sinusoidal border. The texture was sharp on one side of the border, and blurred on the other side. In some presentations the border itself was also blurred. Results showed that blur variation alone is sufficient to determine the apparent depth ordering. A subsequent series of experiments measured blur-discrimination thresholds with stimuli similar to those used in the depth-ordering experiment. Weber fractions for blur discrimination ranged from 0.28 to 0.56. It is concluded that the utility of blur variation as a depth cue is constrained by the relatively mediocre ability of observers to discriminate different levels of blur. Blur is best viewed as a relatively coarse, qualitative depth cue.

A Variant of the Anomalous Motion Illusion Based upon Contrast and Visual Latency

Perception ◽  
10.1068/p5362 ◽  
2007 ◽  
Vol 36 (7) ◽  
pp. 1019-1035 ◽  
Author(s):  
Akiyoshi Kitaoka ◽  
Hiroshi Ashida
Keyword(s):  
Critical Factor ◽  
Luminance Contrast ◽  
High Contrast ◽  
Illusory Motion ◽  
Low Contrast ◽  
Motion In Depth ◽  
Contrast Pattern ◽  
Pulfrich Effect ◽  
Series Of Experiments ◽  
Visual Delay

We examined a variant of the anomalous motion illusion. In a series of experiments, we ascertained luminance contrast to be the critical factor. Low-contrast random dots showed longer latency than high-contrast ones, irrespective of whether they were dark or light (experiments 1–3). We conjecture that this illusion may share the same mechanism with the Hess effect, which is characterised by visual delay of a low-contrast, dark stimulus in a moving situation. Since the Hess effect is known as the monocular version of the Pulfrich effect, we examined whether illusory motion in depth could be observed if a high-contrast pattern was projected to one eye and the same pattern of low-contrast was presented to the other eye, and they were binocularly fused and swayed horizontally. Observers then reported illusory motion in depth when the low-contrast pattern was dark, but they did not when it was bright (experiment 4). Possible explanations of this inconsistency are discussed.

A General Multivariate Dose–Response Model

1986 ◽  
Vol 43 (9) ◽  
pp. 1684-1693 ◽  
Author(s):  
J. Schnute ◽  
J. O. T. Jensen
Keyword(s):  
Environmental Factors ◽  
General Model ◽  
Arbitrary Number ◽  
Biological Response ◽  
Critical Factor ◽  
Companion Paper ◽  
Community Response ◽  
Relative Importance ◽  
Response Model ◽  
Number Of Factors

This paper presents a general model for describing and predicting biological response to environmental factors. The theory embraces concepts and models used in earlier studies of the effects of toxicity on fish, and it extends these ideas in several directions. It can include an arbitrary number of factors, either detrimental or beneficial to the organism. Also, its statistical formulation allows (1) hypothesis testing to determine the relative importance of various factors and (2) calculation of critical factor levels that (with prescribed confidence) assure a community response no worse than a specified level. Our model is based on earlier work by Schnute and McKinnell, and, like theirs, its parameters have biologically meaningful interpretations. Our discussion includes an explanation of how the model relates specifically to toxicity studies. In a companion paper (Can. J. Fish. Aquat. Sci. 43: 1694–1709), we use our model to investigate salmonid response to gas supersaturation and ancillary factors.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

A Method for Setting the Clearance Angle

1972 ◽  
Vol 30 ◽  
pp. 388-389
Author(s):  
Michael T. Bucek ◽  
Howard J. Arnott
Keyword(s):  
Experimental Evidence ◽  
Light Source ◽  
Black Spot ◽  
Critical Factor ◽  
Clearance Angle ◽  
Crude Approximation ◽  
Ultrathin Sections

It is believed by the authors, with supporting experimental evidence, that as little as 0.5°, or less, knife clearance angle may be a critical factor in obtaining optimum quality ultrathin sections. The degree increments located on the knife holder provides the investigator with only a crude approximation of the angle at which the holder is set. With the increments displayed on the holder one cannot set the clearance angle precisely and reproducibly. The ability to routinely set this angle precisely and without difficulty would obviously be of great assistance to the operator. A device has been contrived to aid the investigator in precisely setting the clearance angle. This device is relatively simple and is easily constructed. It consists of a light source and an optically flat, front surfaced mirror with a minute black spot in the center. The mirror is affixed to the knife by placing it permanently on top of the knife holder.

The IBM-PC in electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 612-613
Author(s):  
James F. Mancuso
Keyword(s):  
Head Start ◽  
Image Acquisition ◽  
Cost Effective ◽  
Financial Applications ◽  
Number Of Factors ◽  
Instrument Control ◽  
The Cost ◽  
Training And Support ◽  
Control Image ◽  
Ibm Pc

IBM PC compatible computers are widely used in microscopy for applications ranging from control to image acquisition and analysis. The choice of IBM-PC based systems over competing computer platforms can be based on technical merit alone or on a number of factors relating to economics, availability of peripherals, management dictum, or simple personal preference.IBM-PC got a strong “head start” by first dominating clerical, document processing and financial applications. The use of these computers spilled into the laboratory where the DOS based IBM-PC replaced mini-computers. Compared to minicomputer, the PC provided a more for cost-effective platform for applications in numerical analysis, engineering and design, instrument control, image acquisition and image processing. In addition, the sitewide use of a common PC platform could reduce the cost of training and support services relative to cases where many different computer platforms were used. This could be especially true for the microscopists who must use computers in both the laboratory and the office.

Slip traces caused by plastic deformation during recrystallization of thin metal sheets

1994 ◽  
Vol 52 ◽  
pp. 620-621
Author(s):  
H. Lin ◽  
D. P. Pope
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Sample Thickness ◽  
List Type ◽  
Metal Sheets ◽  
Second Phases ◽  
Slip Traces ◽  
Series Of Experiments ◽  
Cold Rolled ◽  
Individual Grains

During a study of mechanical properties of recrystallized B-free Ni3Al single crystals, regularly spaced parallel traces within individual grains were discovered on the surfaces of thin recrystallized sheets, see Fig. 1. They appeared to be slip traces, but since we could not find similar observations in the literature, a series of experiments was performed to identify them. We will refer to them “traces”, because they contain some, if not all, of the properties of slip traces. A variety of techniques, including the Electron Backscattering Pattern (EBSP) method, was used to ascertain the composition, geometry, and crystallography of these traces. The effect of sample thickness on their formation was also investigated.In summary, these traces on the surface of recrystallized Ni3Al have the following properties:1.The chemistry and crystallographic orientation of the traces are the same as the bulk. No oxides or other second phases were observed.2.The traces are not grooves caused by thermal etching at previous locations of grain boundaries.3.The traces form after recrystallization (because the starting Ni3Al is a single crystal).4.For thicknesses between 50 μm and 720 μm, the density of the traces increases as the sample thickness decreases. Only one set of “protrusion-like” traces is visible in a given grain on the thicker samples, but multiple sets of “cliff-like” traces are visible on the thinner ones (See Fig. 1 and Fig. 2).5.They are linear and parallel to the traces of {111} planes on the surface, see Fig. 3.6.Some of the traces terminate within the interior of the grains, and the rest of them either terminate at or are continuous across grain boundaries. The portion of latter increases with decreasing thickness.7.The grain size decreases with decreasing thickness, the decrease is more pronounced when the grain size is comparable with the thickness, Fig. 4.8.Traces also formed during the recrystallization of cold-rolled polycrystalline Cu thin sheets, Fig. 5.

Dissection of the molecular mechanisms of protein targeting to the peroxisome using immunofluorescence and immunocryoelectron microscopies

1990 ◽  
Vol 48 (3) ◽  
pp. 44-45
Author(s):  
G-A. Keller ◽  
S. J. Gould ◽  
S. Subramani ◽  
S. Krisans
Keyword(s):  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Protein Targeting ◽  
Firefly Luciferase ◽  
Peroxisomal Enzyme ◽  
Transfected Cells ◽  
Peroxisomal Targeting ◽  
Targeting Signal ◽  
Series Of Experiments ◽  
Peroxisomal Targeting Signal

Subcellular compartments within eukaryotic cells must each be supplied with unique sets of proteins that must be directed to, and translocated across one or more membranes of the target organelles. This transport is mediated by cis- acting targeting signals present within the imported proteins. The following is a chronological account of a series of experiments designed and carried out in an effort to understand how proteins are targeted to the peroxisomal compartment.-We demonstrated by immunocryoelectron microscopy that the enzyme luciferase is a peroxisomal enzyme in the firefly lantern. -We expressed the cDNA encoding firefly luciferase in mammalian cells and demonstrated by immunofluorescence that the enzyme was transported into the peroxisomes of the transfected cells. -Using deletions, linker insertions, and gene fusion to identify regions of luciferase involved in its transport to the peroxisomes, we demonstrated that luciferase contains a peroxisomal targeting signal (PTS) within its COOH-terminal twelve amino acid.

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