Contour interaction in fovea and periphery

It has been known for some time that both foveal and peripheral visual acuity are higher for single letters than for letters in a row. Early work showed that this was due to the destructive interaction of adjacent contours (termed contour interaction). It has been assumed to have a neural basis, and a number of competing explanations have been advanced that implicate either high-level or low-level stages of visual processing. Our previous results for foveal vision suggested a much simpler explanation, one determined primarily by the physics of the stimulus rather than the physiology of the visual system. We show that, under conditions of contour interaction or crowding, the most relevant physical spatial-frequency band of the letter is displaced to higher spatial frequencies and that foveal vision tracks this change in spatial scale. In the periphery, however, beyond 5 degrees, the physical explanation is not sufficient. Here we show that there are genuine physiological lateral spatial interactions, which are due to changes in the spatial scale of analysis.     

Real-time location of multiple time-varying strain disturbances,acting over a 40-km fiber section, using a novel dual-Sagnacinterferometer

Updated results using a novel sensing architecture based on a Sagnac interferometer are presented and, for the first time, real-time separation and positioning of multiple disturbances has been realized. A 40-km long dual-Sagnac sensor was formed by spectral slicing of light from a single, broad-band erbium-doped-fiber super-luminescent source and wavelength division multiplexed (WDM) routing around the loop to form an inherently low loss system. Independent active phase biasing of each Sagnac was employed, allowing the use of a single optical detector. The effects of residual optical cross talk between the two Sagnacs has been accurately modeled, allowing resulting errors to be corrected. The new system has capability for narrow-band fast Fourier transform (FFT) analysis of detected disturbance signals, and hence their separation in the frequency domain. For audio-frequency excitation, an average positional resolution of 100 m over a 40-km length was achieved with a postdetection signal processing bandwidth of 8 Hz     

Are developers morally challenged?

Having recently concluded another sordid software development affair, the author is again pondering a question: do computer programmers have ethics or morals? Time and time again he has seen an investment lost, a deal disrupted, or a business destroyed because a programmer acted without regard to fairness or legal rights. Does this conduct reflect a shortcoming in the character of computer programmers, or are they somehow victims who cannot be held responsible for their conduct? How can programmers take such pride in their own work yet have little or no respect for the work of others? Even thieves honor each other. Legal and policy aspects of information technology use and development are discussed     

Grading textile fastness. Part 4: An inter‐laboratory trial using DigiEye systems†,‡

In Part 1 of this series of papers, a new method for assessing textile fastness using an imaging system based upon a digital camera was introduced. In Parts 2 and 3, all available experimental data were used to develop new fastness formulae for assessing staining and change in colour, respectively. The combination of the digital method and the two formulae markedly outperformed the current ISO formulae. In the present study a further inter‐laboratory trial has been conducted under the auspices of TCI/81, Colour Fastness and Colour Measurement Committee. Twelve laboratories and 38 professional assessors took part in this trial. Two Digi‐Eye systems were used to measure all the colours. The results provide strong evidence that the newly developed formulae together with the digital imaging method can accurately predict the visual results.     

Absence of contour linking in peripheral vision

Human foveal vision is subserved initially by groups of spatial, temporal and orientational 'filters', the outputs of which are combined to define perceptual objects. Although a great deal is known about the filtering properties of individual cortical cells, relatively little is known about the nature of this 'linking' process. One recent approach has shown that the process can be thought of in terms of an association field whose strength is determined conjointly by the orientation and distance of the object. Here we describe a fundamental difference in this feature-linking process in central and peripheral parts of the visual field, which provides insight into the ways that foveal and peripheral visual perception differ. In the fovea, performance can be explained only by intercellular linking operations whereas in the periphery intracellular filtering will suffice. This difference represents a substantial economy in cortical neuronal processing of peripheral visual information and may allow a recent theory of intercellular binding to be tested.     

Integration, segregation, and binocular combination

The human visual system can accurately judge the mean of a distribution of different orientation samples. We ask whether the site of this integration is before or after the sites of binocular combination and disparity processing. Furthermore, we are interested in whether the efficiency with which local orientation information is integrated depends on the eye of origin. Our results suggest that orientation integration occurs after binocular integration but before disparity coding. We show that the effectiveness of added orientation noise is not only less than expected on signal or noise grounds but also that it depends on the dominance of the eye to which it is presented, suggesting an interocular opponent interaction in which the dominant eye input has higher gain.     

Grading textile fastness. Part 1; Using a digital camera system

This paper describes an imaging system based upon a digital camera for assessing the fastness of textile materials to staining and colour-change. Large sets of samples were assessed by a panel of professional assessors and these results were used to evaluate the inter-observer and between-laboratory variations, and the instrumental method against the visual results. In addition, the measured results from a camera imaging system and a spectrophotometer are compared. The results show excellent agreement between the two instrumental methods. The agreement is even better than the inter-observer and between-laboratory agreements. It was also found that the present ISO standard formula gave a very poor prediction to the visual results for staining fastness. After a simple correction, the formula fits the data much better. In conclusion, applying a digital camera system plus a revised ISO formula can provide an accurate and rapid method for assessing textile fastness.     

Twelve years of injectable contraceptive use in a general practice

OBJECTIVE: To present our experience with the use of ultrasonography in the evaluation of hysterectomized patients. METHODS: The study group was comprised of 100 consecutive women referred to our ambulatory unit for pelvic sonographic evaluation between April 1, 1996 and March 31, 1997. Inclusion criteria were previous hysterectomy for a benign condition with or without concomitant bilateral salpingo-oophorectomy and available medical and gynecological histories. RESULTS: No significant difference was observed in the rate of abnormal ultrasonographic findings among the patients who had had bilateral salpingo-oophorectomy 5/50 and those who had not (8/50). There was also no significant difference in pelvic mass rate between the patients who were receiving hormone replacement therapy and those who were not. The sensitivity of sonography in our study was 100% and the positive predictive value, 84.5%. CONCLUSIONS: Sonography is a useful diagnostic tool in the follow-up and management of post-hysterectomy patients.     

FONI-SPATE: A new fibre optic stress/strain sensor, using anear-infrared variant of the SPATE effect

A new fibre optic stress/strain sensor, for monitoring hot materials is reported. The fibre collects grey body emission from a heated material sample. When the sample is subjected to transient stresses, the radiation is modulated due to the adiabatic changes in its temperature. The modulation is monitored, via a silica fibre, using a near-infrared GaInAs photodetector. This is also believed to be the first demonstration of the SPATE method in the near infrared