bluuebunny/crossref_metadata_2025 huggingface dataset:
New developments in robust synthesis with antiwindup compensation.Flight control actuators applications
Authors: Ursu Felicia , Ursu Ioan , Iorga Lucian
Published: January 2007

We first summarize some results recently published by the authors on the application of classical robust servomechanism problem (RSP) to electrohydraulic servos. We present a solution consisting of three compensators: an integrator of the tracking error, a LQR stabilizing compensator and an antiwindup compensator. In this work we extend the analysis of the proposed solution by investigating the stability of the closed loop system with saturated control. We present here an approach to this problem based on the Lyapunov function method. The domain of attraction of the origin is obtained and it is shown that the system stability is ensured by simply choosing a particular compensator design which solves RSP. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tip Vortex Wake Destabilization with and without Winglets
Authors: Hörnschemeyer Ralf , Kauertz Sebastian , Haverkamp Sven , Neuwerth Günther , Henke Rolf
Published: January 2007

Wake vortices are an inevitable by‐product of lift. Another airplane following too closely can be dangerously influenced by induced rolling moments. Consistent adherence to the prescribed safety margins ensures safe flight, however it also obstructs the capacity of large airports. To remedy the expected future capacity problems, research is being carried out world wide. This paper describes some results of the research work to decrease the hazard of the vortex wake accomplished at the ILR. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of mercerization of the bamboo strips on the impact properties and morphology of unidirectional bamboo strips–novolac composites
Authors: Das Mahuya , Chakraborty Debabrata
Published: January 2007

Bamboo strips were mercerized with varying concentrations of NaOH (10, 15, 20, and 25%). Impact test was made on composites made from the untreated as well as from the mercerized strips. Works of fracture for all the composites were evaluated and it was observed that the fracture energy undergoes an increase from composites made of untreated bamboo strips to those made from mercerized bamboo strips. Mercerization removed alkali sensitive material from the bamboo matrix and it leads to more cellulose fibril pull‐out from the lignocellulosic composites, which plays a great role in improving the work of fracture value. POLYM. COMPOS., 28:57–60, 2007. © 2007 Society of Plastics Engineers
Effect of chemical structure and composition of the resin phase on vinyl conversion of amorphous calcium phosphate‐filled composites
Authors: Skrtic D , Antonucci JM
Published: January 2007

The objective of this study was to elucidate the effect of chemical structure and composition of the polymer matrix on the degree of vinyl conversion (DC) of copolymers (unfilled resins) and their amorphous calcium phosphate (ACP) composites attained upon photopolymerization. The DC can also be an indicator of the relative potential of these polymeric materials to leach out into the oral environment un‐reacted monomers that could adversely affect their biocompatibility. The following resins were examined: (1) 2,2‐bis[p‐(2′‐hydroxy‐3′‐methacryloxypropoxy)phenyl]propane (Bis‐GMA)/triethylene glycol dimethacrylate (TEGDMA) (1:1 mass ratio; BT resin) combined with hydroxyethyl methacrylate (HEMA; BTH resin) and with HEMA and zirconyl dimethacrylate (BTHZ resin); (2) urethane dimethacrylate (UDMA)/HEMA resins; and (3) pyromellitic glycerol dimethacrylate (PMGDMA)/TEGDMA (PT resin). To make composite specimens, resins were mixed with a mass fraction of 40% zirconia‐hybridized ACP. Copolymers and their composites were evaluated using near infrared spectroscopy for DC after 1 d and 28 d post‐cure at 23 °C. Inclusion of HEMA into the BT and UDMA resins yielded copolymers and composites with the highest DCs. The significantly lower DCs of PT copolymers and their composites are attributed to the rigid aromatic core structure, tetravinyl functionality and limited methacrylate side‐chain flexibility of the surface‐active PMGDMA monomer. There was, however, an increase in the 28 d DC for the PT materials as there was for the BTHZ system. Surprisingly, the usual decrease observed in DC in going from unfilled polymer to composite was reversed for the PT system. Published in 2007 by John Wiley & Sons, Ltd
The influence of hard‐segments on two‐phase structure and shape memory properties of PCL‐based segmented polyurethanes
Authors: Ping Peng , Wang Wenshou , Chen Xuesi , Jing Xiabin
Published: January 2007

Poly(ε‐caprolactone)‐based segmented polyurethanes (PCLUs) were prepared from poly(ε‐caprolactone) diol, diisocyanates (DI), and 1,4‐butanediol. The DIs used were 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluenediisocyanate (TDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI). Differential scanning calorimetry, small‐angle X‐ray scattering, and dynamic mechanical analysis were employed to characterize the two‐phase structures of all PCLUs. It was found that HDI‐ and MDI‐based PCLUs had higher degree of microphase separation than did IPDI‐ and TDI‐based PCLUs, which was primarily due to the crystallization of HDI‐ and MDI‐based hard‐segments. As a result, the HDI‐based PCLU exhibited the highest recovery force up to 6 MPa and slowest stress relaxation with increasing temperature. Besides, it was found that the partial damage in hard‐segment domains during the sample deformation was responsible for the incomplete shape‐recovery of PCLUs after the first deformation, but the damage did not develop during the subsequent deformation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 557–570, 2007
Palivizumab efficacy in preterm infants with gestational age ≤30 weeks without bronchopulmonary dysplasia
Authors: Grimaldi Marianne , Gouyon Béatrice , Sagot Paul , Quantin Catherine , Huet Frédéric , Gouyon Jean‐Bernard ,   for the Burgundy Perinatal Network
Published: January 2007

The present study was designed to determine the efficacy of administration of palivizumab to preterm infants with gestational age (GA) ≤30 weeks without bronchopulmonary dysplasia (BPD). All patients born with GA ≤30 weeks without BPD on Day 28 and hospitalized for RSV bronchiolitis in Burgundy (12 hospitals) from December 1 to April 30 of the next year were included in this prospective observational study during five successive RSV seasons (1999–2000, 2000–2001, 2001–2002, 2002–2003, and 2003–2004). Palivizumab was given to premature infants with a gestational age ≤30 weeks without BPD in the 2002–2003 and 2003–2004 periods only. In the cohort of premature infants with GA ≤30 weeks without BPD, the respiratory syncytial virus (RSV) bronchiolitis hospitalization rate was reduced significantly (P < 0.01) in the two seasons with palivizumab prophylaxis (2002–2003: 0% and 2003–2004: 2%) versus the three previous RSV seasons (1999–2000: 14.3%; 2000–2001: 16.7%; 2001–2002: 10.2%). The number needed to treat to prevent one hospitalization for RSV bronchiolitis was 6 (95%CI: 4–11). Such favorable results have not been always found in the few available postmarketing epidemiological studies on hospitalization rate after palivizumab prophylaxis. Differences in health care organization could explain those discrepancies. Pediatr Pulmonol. 2007; 42:189–192. © 2007 Wiley‐Liss, Inc.
Cardiopulmonary responses of asthmatic children to exercise: Analysis of systolic and diastolic cardiac function
Authors: Alioglu Bulent , Ertugrul Turkan , Unal Mehmet
Published: January 2007

The aim of this study was to evaluate aerobic exercise capacity, cardiac features and function in a group of asthmatic children who underwent medical treatment. Dynamic exercise testing was done to evaluate aerobic exercise capacity. Echocardiography was performed to identify the effects that asthma‐induced pulmonary changes have on respiratory and cardiac function in these patients. The study involved 20 asthmatic children (aged 7–16 years) who were followed at our hospital and 20 age‐ and sex‐matched, healthy control subjects. Sixteen of the asthma cases were moderate and four were severe. All 40 subjects underwent similar series of assessments: multiple modes of echocardiography, treadmill stress testing, pulmonary function testing. The means for forced expiratory volume in 1 sec, forced expiratory flow 25–75%, maximal voluntary ventilation and inspiratory capacity were all significantly higher in the control group. The patient group had significantly lower mean maximal oxygen uptake and mean endurance time than the controls but there were no significant differences between the groups with respect to respiratory exchange ratio or the ventilatory threshold. The control group means for ejection fraction, fractional shortening, left ventricular mass, and left ventricular mass index were significantly higher than the corresponding patient group results. Children with moderate or severe asthma have lower aerobic capacity than healthy children of the same age. The data suggest that most of these children have normal diastolic cardiac function, but exhibit impaired systolic function and have lower LVM than healthy peers of the same age. Pediatr Pulmonol. 2007; 42:283–289. © 2007 Wiley‐Liss, Inc.
Comparative study of the β″‐phase in a 6xxx Al alloy by 3DAP and HRTEM
Authors: Hasting H. K. , Lefebvre W. , Marioara C. , Walmsley J. C. , Andersen S. , Holmestad R. , Danoix F.
Published: January 2007

The metastable β″‐hardening phase in aged 6xxx‐series Al alloys has been investigated by three‐dimensional atom‐probe in order to evaluate the composition (Mg5Si6) of the structure, previously determined by high‐resolution transmission electron microscopy (HRTEM) and electron diffraction. For β″, a significant number of Mg and Si atoms are found to be lost during detection in atom‐probe analysis. The reason of this is non‐resolved events, in which the correlation between the time‐of‐flight (TOF) and the detected position of the field‐evaporated ion is lost. The problem is attributed to uneven evaporation and can be avoided by the use of an advanced delay‐line detector (ADLD), which is capable of discriminating extremely closely spaced detection events. Preliminary analysis of a β″‐particle using this detector gave a Mg/Si ratio of 0.9 and a composition of 15 at.% Al. The Al level is significantly lower than those previously measured by other atom‐probe detectors, because of the higher efficiency of the ADLD in detecting Mg and Si in particles. Atom‐probe analysis with the ADLD detector is consistent with the β″ Mg/Si ratio derived from electron microscopy analysis. The measurements indicate that Al atoms may substitute both Si and Mg positions. Copyright © 2007 John Wiley & Sons, Ltd.
Bitter sweet tympani
Authors: Purohit N , Pratap R , Chawla O P
Published: January 2007

During cholesteatoma surgery, the chorda tympani nerve must often be divided. We present an interesting case of a patient whose severe dysgeusia due to cholesteatoma resolved following section of the chorda tympani nerve.
Decadal variability in the frequency of fall precipitation over the United States
Authors: Small David , Islam Shafiqul
Published: January 2007

We examined decadal variability in fall daily precipitation across the United States over the period 1948 to 2004. By analyzing daily precipitation, we are able to decompose the interannual variability in fall total precipitation into the contributions of variations in the frequency of precipitation and variations in the mean rain day precipitation. Principal components analysis suggests that coherent variations in fall precipitation total across the central United States exhibit strong decadal variability that is due to coherent decadal variations in the frequency of precipitation. A wavelet analysis of regionally averaged total, frequency, and mean rain day precipitation and a series of synthetic experiments that allowed the shape and location of the distribution to change confirmed that the source of the observed decadal variability is the frequency of events rather than changes in the distribution of daily precipitation.
Investigation on the relationship between cannabinoid CB1 and opioid receptors in gastrointestinal motility in mice
Authors: Carai M A M , Colombo G , Gessa G L , Yalamanchili R , Basavarajappa B S , Hungund B L
Published: January 2007

British Journal of Pharmacology (2007) 150, 249. doi:10.1038/sj.bjp.0707128
Electrical characterization of a capacitive rf plasma sheath
Authors: Gahan D. , Hopkins M. B.
Published: January 2007

The authors report on an experimental system designed to investigate and characterize capacitive radio frequency (rf) sheaths. An electrode mounted in an inductive plasma reactor and driven with separate rf and direct current (dc) power sources is used. The advantage of this design is that the electrode sheath is decoupled from the plasma parameters. This allows detailed investigation of the sheath with different bias conditions without perturbing the bulk plasma parameters. Power coupled to ions and electrons through the sheath, at low pressure, is investigated and a method to determine the electron conduction current to the electrode, using the external dc bias, is presented.
Experimental quantum key distribution with active phase randomization
Authors: Zhao Yi , Qi Bing , Lo Hoi-Kwong
Published: January 2007

Phase randomization is an important assumption made in many security proofs of practical quantum key distribution (QKD) systems. Here, the authors present the first experimental demonstration of QKD with reliable active phase randomization. One key contribution is a polarization-insensitive phase modulator, which they added to a commercial phase-coding QKD system to randomize the global phase of each bit. They also proposed a useful method to verify the phase randomization experimentally. Their result shows very low quantum bit error rate (<1%). They expect this active phase randomization process to be a standard part in future QKD setups due to its significance and feasibility.
Hearing: Individual Differences in Perceiving
Authors: McGuinness Diane
Published: January 2007

Four different types of hearing were investigated using 25 men and 25 women as subjects: pure tone threshold, judgment of loudness, pitch discrimination, and annoyance of a repeating stimulus.

Differences were found at high frequency thresholds (above 6000 Hz), in loudness judgment, and in the annoyance test. The pitch discrimination test showed no effect of sex, but a large effect of years of musical training. None of the four hearing parameters investigated bore any statistical relationship to any other, demonstrating that these hearing types are distinct and will vary within, as well as between subjects. Personality assessment showed no relationship to any type of-hearing, with the exception of extraversion and loudness judgment, suggesting that fairly pure sensitivity factors are being measured.
Pattern Learning and the Control of Behaviour by All-Inhibitory Neural Network Hierarchies
Authors: Dobson Vernon
Published: January 2007

An all-inhibitory network which learns by selective disconnection of synapses is described. This is similar to an ‘associative net'; however, it is simpler in that its neurons do not need to perform arithmetical operations, and the net does not require additional threshold modulating neurons in order to cope with input patterns which are incomplete, or of differing sizes.

This fundamental simplicity permits a greater variety and density of connections. These can multiply the capacity of the nets to learn complex sequences of patterns without being saturated. An “all-connected‘’ net is described which has the holograph-like capacity to reconstruct the whole of an input pattern from part patterns without involving delays or threshold devices.

All of these inhibitory nets can construct themselves by means of simple random growth processes, without incurring any loss of learning capacity of holographic properties. Similarly, synapses can be allowed to potentiate with use, so that reaction times are progressively reduced by practice, without any reduction in the quality of the performance.

Inhibitory connections between arrays can give patterns in one array control over the allocation of channels in which lower arrays store learned information. A description is given of a model, decentralised, inhibitory hierarchy consisting of inter-connected arrays which can learn to execute goal-directed TOTE-type programs of behaviour by means of a simple ‘putting-through’ procedure.
The Perception of Familiar Stimuli
Authors: Pickering John
Published: January 2007

A model is described for the processing of word-like (regular) and nonword-like (irregular) letter strings in a situation where either type of string may occur. It is proposed that each type of string is processed by specialised routines which are deployed contingently on an initial decision about the regularity of an item. Three experiments involving word/nonword and same/different responses investigate how the processing of a string is affected by the brief exposure of a prior string. It is shown that processing is interfered with less when both strings are of the same degree of regularity than when they are not.

The model is revised and extended in the light of the results obtained as well as some theoretical considerations.
Existence and Implications of a Tilted Binocular Disparity Space
Authors: Breitmeyer Bruno , Battaglia Frank , Bridge Jacque
Published: January 2007

The existence of a tilted binocular disparity space was experimentally established. The results of the experiment showed that a texture surface which under binocular viewing appears to be oriented vertically and perpendicular to the line of sight in fact is tilted such that the portions of the texture surface above and below fixation incline toward and away from the observer, respectively. Under monocular viewing such a discrepancy between apparent and objective vertical tilt is not observed. This suggests that under binocular viewing the cortical representations of the upper and lower visual hemifields are biased toward uncrossed and crossed disparities, respectively. The tilted binocular disparity space is explained in terms of an experientially induced disparity gradient effected during development of the binocular system.
Global Processes in Stereopsis: Some Comments on Ramachandran and Nelson (1976)
Authors: Frisby John P , Mayhew John E W
Published: January 2007

The use of the term ‘global’ in the context of stereopsis is discussed. It is concluded that different meanings of this term need to be kept carefully distinguished at all times. The discussion centres around a series of demonstrations introduced by Ramachandran and Nelson, and interpretations are offered for these demonstrations in terms of spatial-frequency-tuned stereopsis channels.
Pattern Structure and Relational Discrimination Learning
Authors: Dodwell Peter C
Published: January 2007

McGonigle and Jones take exception to Dodwell's explanation of anomalous transfer (AT) as the outcome of relational discriminations among a set of stimulus patterns which vary along a single dimension of orientational salience, from ‘horizontal’ to ‘vertical’. In particular they do not think that the continuum is generated by units with Hubel-and-Wiesel type retinal receptive fields. Instead, they invoke Garner's notions about stimulus structure to explain Dodwell's results, as well as their own finding of two situations where AT fails to occur. It seems that McGonigle and Jones missed the point of the relational discrimination explanation of AT. In fact, it is shown that AT is not predicted by this model for the conditions in which they failed to obtain it.

The relational model makes definite predictions about conditions under which AT will occur; as this is not true of their invocation of Garner's ideas, the former is to be preferred. Whether or not outputs are coded by Hubel-and-Wiesel type units is not particularly relevant to the main point, that AT is a result of relational learning. In fact, the model is an instance of how structure, in Garner's sense, can be generated.
Effects of Gap Size between Shaft and Fins and of Angle of Fins on the Müller—Lyer illusion
Authors: Pressey Alexander W , Di Lollo Vincent , Tait Robert W
Published: January 2007

Assimilation theory was employed to generate quantitative predictions relating the ingoing Müller—Lyer illusion to both angle of fin and gap between shaft and fin. Gap sizes were varied from zero to 18 mm in steps of 2 mm, and angles of fins were varied from 30° to 180° in steps of 30°. Five subjects adjusted the length of a comparison line to match the apparent length of the shaft at each combination of gap size and angle of fin. It was predicted that the gap necessary for a reversed illusion to occur, and the gap at which the maximal reversed effect occurred, would be inversely related to angle of fins. Empirical functions verified the predictions.
The Role of Apparent Depth and Context in the Perception of the Ponzo Illusion
Authors: Schiffman Harvey R , Thompson Jack G
Published: January 2007

The role of apparent depth features and the proximity of the test lines to the adjacent contours in the actuation of the Ponzo illusion was examined. Six versions of the Ponzo figure were employed: a standard Ponzo figure and five modified figures in which the test lines varied in orientation (horizontal or vertical) and in location (inside or outside the converging contours). Both manipulations resulted in a significant decrease in the magnitude of the illusion in comparison to the standard Ponzo figure. The results suggest that the Ponzo illusion is significantly affected by contextual factors.
Feedback versus an Illusion in Time
Authors: Jamieson Donald G , Petrusic William M
Published: January 2007

The accuracy of many perceptual comparisons depends greatly on the order in which the to-be-compared stimuli are presented. With comparisons of durations around 300 ms, these presentation-order effects do not diminish, even with extended practice, when feedback about response accuracy is withheld. Providing such feedback greatly diminishes presentation-order effects and coincidentally produces substantial increases in response accuracy. The feedback acts in part through inducing response biases and in part through changes in sensitivity. The contradiction between studies which report time-order errors in duration comparison and those which do not is attributable to differences in the use of information feedback.
Perception of Contour in Music Reading
Authors: Sloboda John A
Published: January 2007

Musicians and nonmusicians were required to make written reports of briefly presented displays of pitch symbols. Whilst musicians were not superior to nonmusicians at identifying individual notes they were superior at retaining information about the contour of note sequences. In addition, manipulation of task difficulty by requiring whole or partial report of the displays had a significant effect on performance only when global, rather than specific, response measures were taken. The results are in accordance with the theory that global analysis precedes detailed analysis in perceptual processing.
Form Aftereffect Contingent upon a Colour Shift
Authors: Dawson Benjamin M , Stromeyer Charles F
Published: January 2007

After prolonged fixation of coloured gratings of low spatial frequency, images of the gratings can be elicited up to 90 min thereafter when the colour of a spatially homogeneous test field is suddenly changed. Only adapting gratings with luminance contrast induce clear aftereffects. Control experiments rule out afterimages as an explanation of the aftereffects.
McCollough Effect and Eye Optics
Authors: Hohmann Annemarie , von der Malsburg Christoph
Published: January 2007

Astigmatism induced by cylindrical lenses leads to colour sensations similar to the McCollough effect. Consequences for the design of experiments and a new interpretation of the McCollough effect are suggested.
Parotid and Whole-Mouth Secretion in Response to Viewing, Handling, and Sniffing Food
Authors: Pangborn Rose Marie , Witherly Steven A , Jones Frances
Published: January 2007

There was no significant change in flow rates of parotid saliva in nineteen of twenty subjects while they viewed photographs of lemons, or in fourteen of twenty subjects while they cut lemons in a glove box. Neither parotid nor whole-mouth secretion changed from baseline when subjects viewed fresh lemons and lemonade presented in a plastic box. Further, no significant changes in whole-mouth secretion rates were observed when subjects viewed photographs of two appetizing foods, or of fresh doughnuts in a plastic box, even though subjects knew they could eat the doughnuts after the experiment. In most cases, sniffing of the lemons or of the doughnuts resulted in increased flow rates. Subjects demonstrated large differences in their patterns of affective responses to full-strength and diluted lemon juice, which were independent of salivary flow. In the absence of olfactory or tactile stimulations, few subjects altered parotid or whole-mouth secretion rates in response to viewing food or photographs of food. A reevaluation of findings on ‘psychic’ stimulation of saliva may be in order to ascertain the role of olfactory, tactile, and even trigeminal clues in salivary response to food stimuli.
Scanning Visual Images: Implications for the Representation of Space
Authors: Beech John R
Published: January 2007

This study investigated whether reaction time to detect an item within an image increases as a monotonic function of the relative or the absolute distance from the starting item to the probed item within the image. It was found that when relative probed distances were manipulated and absolute distances kept constant and, conversely, when absolute distances were manipulated and relative distances kept constant, reaction times were invariant across relative distance but increased as a function of increasing absolute distance. This result may be interpreted either in terms of operations within an imaginal representation or in terms of operations on propositional statements underlying the image.
Gross Failure to Utilise Alignment Cues in Children's Drawing of Three-Dimensional Relationships
Authors: Freeman Norman , Hayton Claire
Published: January 2007

There are two major ways of classifying the development of children's attempts to represent three-dimensional relationships on the page. One is in terms of discrete drawing systems and the other is in terms of local decisions that have to be taken within more than one system.

An observation is made which appears paradoxical from each of these approaches. Nonetheless, study of the observation reveals a systematic relationship with a systems approach. But this cannot be explained without extending the assumptions of a systems approach.
Adaptation to Visual Displacement: Contribution of Proprioceptive, Visual, and Attentional Factors
Authors: Mather Jennifer A , Lackner James R
Published: January 2007

A study is reported of the sensory and oculomotor factors that influence adaptation to visual displacement when only sight of the hand and of a target light is permitted. Ten subjects each participated in five counterbalanced sessions in which the relative contributions to adaptation of limb proprioception, oculomotor pursuit, retinal image displacement, and attention were determined. Recordings of eye position were taken throughout the sessions. A discordance between the visual direction of the hand and the proprioceptively specified position of the hand was essential but not sufficient for adaptation to occur. When such a discordance was present adaptation was enhanced by improving position sense of the arm by moving it passively, maximizing accuracy of visual tracking, and focusing attention on the hand. Attentional factors played a smaller part than has been reported for exposure situations involving error feedback about limb position. Eye-movement recordings showed that tracking the passively moved hand visually was vastly superior to tracking a target light undergoing comparable motion.
Interlimb Transfer after Adaptation to Visual Displacement: Patterns Predicted from the Functional Closeness of Limb Neural Control Centres
Authors: Elliott Digby , Roy Eric A
Published: January 2007

Two experiments were designed to determine whether interlimb transfer of prism adaptation follows a pattern predicted by the functional closeness of limb control centres. Subjects were adapted to a lateral displacing prism with their right arm in conditions known to facilitate interlimb transfer. Negative aftereffect measures of target-pointing shift were taken for all limbs. If transfer to the unadapted limbs is primarily the result of some sort of visual change, scores for those limbs should not differ. However, if the functional cerebral closeness of limb control centres is a factor, the greatest shift should be evidenced in the homologous contralateral limb (left arm), followed by the ipsilateral limb (right leg), with the least shift to the diagonally opposite limb (left leg). No differences in shift among the three unadapted limbs was found in the two experiments.
Don Juan and the Vision of Vision
Authors: Smith Christopher U M
Published: January 2007

Castaneda's well-known sequence of Don Juan books is used as a paradigmatic example of the relativist position. Central to Don Juan's teaching is the problem of perception: the main task, he constantly reiterates, is simply to ‘see’, to recognise that the commonsense world we customarily perceive is nothing more than a cultural construct. To combat this thoroughgoing relativism a case study is taken from the early history of visual science. In classical antiquity several fundamentally different ‘views’ (to use Don Juan's term) of how we see contended for approval. It was only at the beginning of the seventeenth century that the ‘modern’ interpretation was selected. This interpretation was selected, ultimately, because it ‘worked’. Reference is made to both Wittgenstein and Marx to support this appeal to praxis. It is argued that through an intricate, complex, and ill-understood process of popularisation our self-image is ultimately grounded in the theories of natural science; and these, in turn, are ultimately grounded in our action in the world of things.
Depth, Connectedness, and Structural Relevance in the Object-Superiority Effect: Line Segments are Harder to See in Flatter Patterns
Authors: Weisstein Naomi , Williams Mary C , Harris Charles S
Published: January 2007

A briefly flashed line can be identified more accurately when it is part of certain types of pattern than in others (the ‘object-superiority effect’). Three experiments were designed to investigate what aspects of these patterns determine the facilitatory effect of context. Subjects identified which of four line segments was present in various briefly flashed figures. Other subjects rated the figures for three-dimensionality, connectedness, and ‘structural relevance’ of the target line. Little relationship was found between connectedness ratings and accuracy in the identification task, but accuracy was highly correlated with mean depth rating (accounting for 95% of the variance) and with mean structural-relevance rating (88%). Because of the high correlation ( r = 0·98) between these two judgments in the present experiments, and confounding with other stimulus variables in previously published studies, the relative importance of these two global attributes cannot yet be determined definitively (though there was some evidence that for these patterns depth judgments were primary and structural-relevance judgments derivative). A reexamination of pertinent research suggests that comparisons between well-matched stimuli (as in the object-superiority effect) are likely to be more robust and informative than comparisons between lines alone and in context (the ‘object-line effect’).
A Nonspecific Learning Effect in the Perception of Random-Dot Stereograms?
Authors: Weinman John , Cooke Vicky
Published: January 2007

An experiment is reported the object of which was to check whether a small amount of nonspecific experience in perceiving random-dot stereograms could facilitate the perception of a previously unseen stereogram. The mean stereopsis perception time of a group of totally naive subjects was found to be significantly slower than that of a group who had previously been shown two different stereograms. Closer inspection of the data showed that this difference was primarily due to approximately one third of the naive group who were much slower than the ‘experienced’ group. It is therefore suggested that nonspecific experience provides most initial help for relatively slow perceivers, since many naive subjects can perform as well as those with prior experience of other stereograms.
Perceived Movement: The Flintstone Constraint
Authors: Bregman Albert S , Mills Michael I
Published: January 2007

Two cartoon animation sequences were presented to subjects to test whether the human visual system prefers to construct the mental representation of movement by transforming already existing forms. The results support the view that the sensory system has developed economical methods for rapidly picking up the structure of any situation and prefers to use revision rather than reconstruction to account for a change in sensory stimulation.
Influence of Spatial Frequency, Luminance, and Duration on Binocular Rivalry and Abnormal Fusion of Briefly Presented Dichoptic Stimuli
Authors: Wolfe Jeremy M
Published: January 2007

Orthogonal gratings, presented dichoptically, do not fuse into a single percept. Parts of each are seen while other parts are suppressed in an unstable perception (binocular rivalry). However, it has been previously noted that, if the gratings are briefly flashed, they will appear to fuse into a plaid or checkerboard pattern. Three experiments are reported which have been designed to define more clearly the spatial and temporal parameters of this effect in the hope that this would lead to better understanding of the normal mechanisms of dominance and suppression. Stimuli appear fused if flashed for less than 150 ms. The effect is independent of substantial changes in spatial frequency and luminance. Single flashes that appear fused when presented in isolation produce rivalry if separated by intervals less than about 150 ms. Intervals greater than 150 ms produce continued abnormal fusion. Possible mechanisms are discussed.
Instability in Triangular-Wave Gratings: A Role for Perceptual Inferences?
Authors: Mapperson Barry , Lovegrove William
Published: January 2007

Recently it has been reported that a grating with a triangular-wave luminance profile may fluctuate between being perceived veridically, and as a percept which more closely resembles a square wave, and is itself bistable. Several additional percepts which may be experienced are reported. It is also noted that the relative dominance of two of these percepts can be altered by either physically present or inferred cues as to the probable direction of illumination. It is suggested that these observations implicate higher-level processes in this new form of perceptual instability.
Illusion of Extent in Simple Angular Figures
Authors: Predebon John
Published: January 2007

With the exception of very small angles (<15°) Heywood and Chessell found systematic misestimations of the baseline distances of angles. Here three experiments are reported two of which indicate that the baseline distances of a wide range of acute angles (<75°) are overestimated while the third confirms Heywood and Chessell's pattern of errors. The results are discussed with reference to a possible confounding present in the method used in the third experiment and, therefore, in the original Heywood and Chessell experiments.
Things are Deeper Than They are Wide: A Strange Error of Distance Estimation
Authors: Hammersley Richard
Published: January 2007

An error of distance judgement is reported: subjects judge a length seen in depth to be greater than the same length seen in width. In depth-to-width comparisons they underestimate depth, and in width-to-depth comparisons they overestimate width. This is hard to explain in both inferential and realist theories of three-dimensional perception. Two plausible accounts of the error are proposed.
Children's Photograph Selections and Verbal Reports in a Spatial Task
Authors: Calam Rachel M
Published: January 2007

The tendency for children to select a photograph of their own view of a scene when asked to represent the view seen by another observer in a different position has been attributed to an egocentric view of the world. It seems likely, however, that the egocentric response need not necessarily be related to the question of sensitivity to the viewpoints of others. Rather, it may reflect the way in which children treat two-dimensional representations of three-dimensional arrays in mental-rotation tasks. In the present investigation, strong visual and verbal cues were given for correct selection of a photograph of another observer's view in a perspective-shift task. Justifications for choices were required. Whilst floor effects were seen with children 3 to 4 years old, the responses of 8-year olds polarised into a choice between the correct and egocentric view, as Freeman would predict. Verbal justifications for these choices were mainly in terms of appropriate content. After first selection, this chosen view was removed from the array. Two-thirds of children who had chosen egocentrically then went on to choose correctly on a second attempt. It is suggested that the egocentric response may form an easier alternative for the child, but that the provision of such an alternative may prevent the child from displaying the knowledge that he or she has.
Head and Body Hemispace to Left and Right III: Vibrotactile Stimulation and Sensory and Motor Components
Authors: Bradshaw John L , Nathan Gregory , Nettleton Norman C , Pierson Jane M , Wilson Lyn E
Published: January 2007

Response latencies were measured to vibrotactile stimulation delivered to the forefingers of the left or right hands which were positioned ipsilaterally or contralaterally (across the midline) in left or right hemispace. While the two hands did not differ in speed of response, either hand performed better when located in right hemispace (experiment 1). This effect was greatly reduced, though not eliminated, with 90° lateral head turn, when performance was better with stimulation and responding in right-of-head hemispace, but not right-of-body hemispace (experiment 2). When different hands stimulation and initiated responses, and were located in either the same or opposite hemispace, right-hemispace superiority was found to be motor rather than sensory (experiment 3). These findings are discussed in the context of the true and the phenomenological midline and the clinical syndrome of hemineglect.
Apparent Relative Size in the Judgement of Apparent Distance
Authors: Burnham Denis K
Published: January 2007

In experiment 1 judgements of the apparent distance of comparison figures (squares or triangles) were obtained under reduction conditions. These comparison figures were either shaped the same as or different from equidistant standard figures, and were half, equal to, or double the area of the standard figures. Apparent distance was found to be a linear function of the relative area of the comparison figure both in same-shape and different-shape stimulus pair conditions. In addition, apparent distance was found to be a function of perceived area, because in different-shape conditions triangles were generally seen to be closer than squares even when the real area of the standard and comparison was equal. The results of experiment 2 and 3 provide some evidence that the effect of different shapes of standard and comparison on apparent distance is due to the observers' perception of the height rather than the area of figures. The series of experiments shows that the traditional transactionalists' explanation of relative size as a cue for distance is inadequate.
Distinguishing Two Classes of Impossible Objects
Authors: Thro E Broydrick
Published: January 2007

Psychologists disagree about what is wrong with the fork. R L Gregory says that its spatial orientation is impossible. J M Kennedy claims that it lacks the intact boundaries characteristic of solid objects. In fact, the fork possesses both these flaws. It cannot be made out of wires because the rectangular/trapezoidal shapes representing its conjoined middle plate and prong create a self-contradictory angle between planes. Further, the fork cannot be cut from a flat sheet of paper because figural contours delineating its boundaries show us self-contradictory transformations of surfaces into air space.

The fork is important because its two flaws form the bases of distinct classes into which all the recognized impossibles fall. Different arrangements of the fork's critical rectangle/trapezoid shapes are the sole source of paradox in ‘depth impossibles’—for instance, the triangle and staircase drawings by R and L S Penrose, the window design published anonymously in Aviation Week & Space Technology in 1964, and Belvedere by M C Escher. And variations on the fork's self-contradictory boundary constitute the only source of paradox in ‘impossible solids’—for instance, Escher's Day and Night, Victor Vasarely's Study in Axonometric Perspective, and Escher's Convex and Concave.
Salt Taste Sensitivity and Stimulus Volume: Sips and Drops. Some Implications for the Henkin Taste Test
Authors: O'Mahony Michael , Atassi-Sheldon Sanah , Wong Joanne , Klapman-Baker Karen , Wong Sau-Yin
Published: January 2007

Various presentation procedures and stimulus volumes were compared in their effect on salt taste sensitivity. For sodium chloride (NaCl) stimuli pipetted onto the tongue, subjects had comparable measured sensitivity to 10 ml and 1 ml volumes but a reduced sensitivity to 0.1 ml volumes. The greatest sensitivity was achieved with 10 ml sipped volumes. Modification of the Henkin dropwise triangluar taste test, by increasing the stimulus volumes, increased subjects' sensitivity. Only the 1 ml pipette presentation increased the sensitivity of the Henkin procedure, albeit slightly, to the detection of changes in taste sensitivity, the purpose for which the procedure was actually designed. Such modification did not perturb salivary NaCl levels more than the regular Henkin procedure, so it would not be expected to introduce sensitivity drift.
Testing a Perceptual Constancy Model for Odor Strength: The Effects of Sniff Pressure and Resistance to Sniffing
Authors: Teghtsoonian Robert , Teghtsoonian Martha
Published: January 2007

The rate at which odorous vapor flows over the receptor surface is reflected in olfactory nerve activity, but the evidence for a corresponding effect on odor strength is scant and inconsistent. A perceptual constancy model for odor strength resolves this apparent contradiction: The effect of flow rate at the receptor site may be perceptually discounted when there is sensory feedback, in the form of perceived effort, from the action of sniffing responsible for changes in flow rate. Previous evidence shows that observers experience change in perceived effort when sniffing at various pressures against fixed resistance but not when sniffing with fixed pressure against varying resistance. Thus the model predicts both that odor strength varies when flow rate is manipulated by changes in olfactory resistance and that odor strength is invariant when flow rate is manipulated by changes in sniff pressure.

In the present study, in which subjects made magnitude estimates of the odor strength of pyridine and n-butanol, an earlier finding for the effects of resistance change was confirmed and extended. Further, within the framework of a single experiment in which both pressure and resistance were independently manipulated, the odor strength of n-butanol conformed to the predictions of the constancy model.
Perception of Glass Pattern Structure with Stereopsis
Authors: Earle David C
Published: January 2007

Stereograms are presented which demonstrate that the perceptual salience of structure in Glass patterns may be destroyed or created by the introduction of stereoscopic depth effects. Novel three-dimensional pattern structures can also be produced. Proposals concerning the nature of the primal sketch are evaluated in the light of these findings, and it is concluded that the findings are consistent with the view that depth derived from disparity information is explicitly represented in the primal sketch.
Effect of Modality-Specific Experience on Visual and Haptic Judgment of Orientation
Authors: Appelle Stuart , Gravetter Frederick
Published: January 2007

Although the ‘oblique effect’ (poorer performance on oblique orientations as compared to performance on vertical and horizontal orientations) is generally understood as a strictly visual phenomenon, a haptic oblique effect occurs for blindfolded subjects required to set a stimulus rod by hand. Because oblique effects are often attributed to the observer's experience with a predominantly horizontal and vertical environment, we assessed the effect of visual and haptic experience by providing subjects with modality-specific inspection periods to familiarize them with the more poorly judged obliques. Oblique error was significantly reduced in magnitude for judgments made by the modality of experience, and for judgments made across modalities. Rate of improvement, consistency of transfer, and the subjective reports of subjects indicate that this haptic oblique effect is more strongly influenced by visual experience and imagery than by haptic experience. It need not be interpreted as an effect based on factors intrinsic to the haptic modality.
Digitized Images: What Type of Grey Scale Should One Use?
Authors: Kingdom Fred , Moulden Bernard
Published: January 2007

One of the issues faced by engineers when designing a system which records an external event and represents it in the form of a digitized image on a VDU screen is which type of grey scale to use. An experiment is described which compares, in a simulated digitized image, the effect of a linear and a logarithmic grey scale on the detectability of a straight-line signal embedded in visual noise. It was found that both bright and dark signals were detected more easily with the linear scale. A signal detection theory analysis was carried out to compare human performance with that of an ‘ideal’ observer who performed the detection task with a filter spatially matched to the signal. It was found that the model of performance for this ideal observer accounted well for the results provided the assumption of a linear transformation of luminance was made. The analysis showed that the superiority of the linear over the logarithmic grey scale was simply due to the higher signal-to-noise ratio of the signals in the former.