We review the use of Cepheids as distance indicators with particular emphasis on the methods which have been applied to HST observations of Cepheids. The calibration of the periodluminosity relations is examined in detail and we identify possible problems with the existing calibrations. New V and I-band period luminosity relations are presented based on a sample of 53 Cepheids in the LMC with p...

Visually, we can extract a statistical summary of sets of elements efficiently. However, our visual system has a severe limitation in that the ability to recognize an object is remarkably impaired when it is surrounded by other objects. The goal of this study was to investigate whether the crowding effect obstructs the calculation of the mean size of objects. First, we verified that the crowdin...

The concept of the crowding-out effect has been employed in tourism literature to analyse complex phenomena. However, there is limited insight into on tourists by tourists, and even less impact distance tourists. This paper examines relationship between crowding perceptions, tourists' attitudes toward consequences being crowded out. Results from a sample 729 international Hong Kong suggest that...

Do we identify an object as a whole or by its parts? This simple question has been surprisingly hard to answer. It has been suggested that faces are recognized as wholes and words are recognized by parts. Here we answer the question by applying a test for crowding. In crowding, a target is harder to identify in the presence of nearby flankers. Previous work has described crowding between object...

Foveal vision in strabismic amblyopia can show increased levels of crowding, akin to typical peripheral vision. Target-flanker similarity and visual-acuity test configuration may cause the magnitude of crowding to vary in strabismic amblyopia. We used custom-designed visual acuity tests to investigate crowding in observers with strabismic amblyopia. LogMAR was measured monocularly in both eyes ...

Crowding is impairment of peripheral object identification by nearby objects. Critical spacing (the minimum target-flanker distance that does not produce crowding) scales with target eccentricity and is consistently reported as roughly equal to or less than 50% of target eccentricity (0.5e). This study demonstrates that crowding occurs far beyond the typical critical spacing when the target is ...

Enhanced spatial processing of local visual details has been reported in individuals with autism spectrum conditions (ASC), and crowding is postulated to be a mechanism that may produce this ability. However, evidence for atypical crowding in ASC is mixed, with some studies reporting a complete lack of crowding in autism and others reporting a typical magnitude of crowding between individuals w...

The allocation of attentional resources to a particular location or object in space involves two distinct processes: an orienting process and a focusing process. Indeed, it has been demonstrated that performance of different visual tasks can be improved when a cue, such as a dot, anticipates the position of the target (orienting), or when its dimensions (as in the case of a small square) inform...

The nondominated sorting genetic algorithm with elitism (NSGA-II) is widely used due to its good performance on solving multiobjective optimization problems. In each iteration of NSGA-II, truncation selection is performed based on the rank and crowding distance of each solution. There are, however, drawbacks in this process. These drawbacks to some extent cause overlapping solutions in the popu...

We consider an optimization deployment problem of multistatic radar system (MSRS). Through the antenna placing and the transmitted power allocating, we optimally deploy the MSRS for two goals: 1) the first one is to improve the coverage ratio of surveillance region; 2) the second goal is to get a even distribution of signal energy in surveillance region. In two typical working modes of MSRS, we...