Search results for "ACCOMMODATION"
showing 10 items of 123 documents
Human eyes do not need monochromatic aberrations for dynamic accommodation
2017
Purpose To determine if human accommodation uses the eye's own monochromatic aberrations to track dynamic accommodative stimuli. Methods Wavefront aberrations were measured while subjects monocularly viewed a monochromatic Maltese cross moving sinusoidally around 2D of accommodative demand with 1D amplitude at 0.2 Hz. The amplitude and phase (delay) of the accommodation response were compared to the actual vergence of the stimulus to obtain gain and temporal phase, calculated from wavefront aberrations recorded over time during experimental trials. The tested conditions were as follows: Correction of all the subject's aberrations except defocus (C); Correction of all the subject's aberratio…
A description model for regeneration through urban tourism in rural towns with underused historic real estate
2016
Il presente contributo propone un modello di descrizione (description model) che trova applicazione in una situazione reale di aiuto alla decisione posto dall'urbanista per lo sviluppo turistico delle città rurali nelle zone dell'entroterra siciliano. Il problema decisionale riguarda la città di Cianciana (AG), che negli ultimi anni si è resa protagonista di un particolare fenomeno di turismo internazionale. In particolare, proponiamo un quadro valutativo multicriteriale per la riqualificazione fisica ed economica del centro storico della città attraverso lo sviluppo del turismo. Il modello presentato, relativo a un problema decisionale di tipo descrittivo, è orientato a supportare i deciso…
Accommodation-related changes in monochromatic aberrations of the human eye as a function of age.
2008
PURPOSE. To investigate the relationship between accommodation and the optical aberrations of the whole human eye, as a function of age. METHODS. Sixty healthy subjects with spherical ametropia in the range 3 D, astigmatism less than 1 D, corrected visual acuity of 20/18 or better, and normal findings in an ophthalmic examination were enrolled. Subjects were divided into four groups, with age ranges of 19 to 29, 30 to 39, 40 to 49, and 50 to 60 years. Monochromatic optical aberrations and pupil size were measured with a Hartmann-Shack wavefront sensor under monocular viewing conditions, without pharmacological dilation or cycloplegia. Stimulus vergences were in the range of 0 to 5 D, with a…
Unobserved tourism
2015
Having more reliable statistics is essential for policy-makers to be able to make effective decisions. Nevertheless, measuring the number of tourists in a given destination is not an easy task. After reviewing the main problems affecting official statistics on tourism, this paper proposes a general framework by formalizing a theoretical model in which tourism nights and trips in a given destination are broken down into observed and unobserved components, according to the European system of tourism statistics. The main approaches related to the measurement of unobserved tourism are discussed, and some empirical findings in Sicily (Italy) are presented in order to highlight the actual magnitu…
What distance do university students walk and bike daily to class in Spain
2016
Abstract Introduction Physical activity levels are low in the general population and these levels decrease from childhood to adolescence, as well as from adolescence to adulthood. Active commuting (AC) is an opportunity to increase the physical activity levels. The distance between home and destinations is a main correlate of AC; however, the distance that university students walk or cycle to university is unknown. Methods Participants self-reported their modes and time of commuting to and from university in a questionnaire, and the main mode of commuting was identified. Moreover, they reported their home address, and the Spanish version of Mapquest software was used to measure street-netwo…
Influencia de los diferentes tipos de astigmatismo en la agudeza visual
2017
[EN] Purpose To investigate the change in visual acuity (VA) produced by different types of astigmatism (on the basis of the refractive power and position of the principal meridians) on normal accommodating eyes. Methods The lens induced method was employed to simulate a set of 28 astigmatic blur conditions on different healthy emmetropic eyes. Additionally, 24 values of spherical defocus were also simulated on the same eyes for comparison. VA was measured in each case and the results, expressed in logMAR units, were represented against of the modulus of the dioptric power vector (blur strength). Results LogMAR VA varies in a linear fashion with increasing astigmatic blur, being the slope o…
Millenials’ intentions to book on Airbnb
2018
The sharing economy has witnessed a significant growth in recent years, enhanced by the development of online platforms. In particular, Airbnb has witnessed a significant worldwide year-on-year growth. Given the importance and popularity of Airbnb, it is crucial to examine which factors affect intentions to book on this website. This study proposes and tests a model based on the Theory of Reasoned Action, to examine millennials’ determinants of intentions to book on Airbnb. Based on two online surveys targeting millennials from Germany and China, the results show that intentions to book on Airbnb is mostly influenced by subjective norm, desire for unique accommodation and variety, attitude …
<title>Additional usage possibilities for the computerized Hess screen</title>
2003
The purpose of the study was to work out a method how to use the computerized Hess screen in proximal vergence measurements. Proximal vergence or vergence due to knowledge of nearness is one of four independent components making up the total vergence response. Proximal vergence is expressed as a ratio - proximal convergence/test distance (PC/T). The computerized Hess screen is usually used to detect and to measure an ocular misalignment in patients with paralytic strabismus in different directions of gaze. The computerized Hess screen can be used to assess PC/T ratio in different directions of gaze, providing the open-loop disparity vergence and accommodation systems and assuming that tonic…
Dynamic accommodation without feedback does not respond to isolated blur cues
2016
Highlights • A new methodology is used to study a potential cue for dynamic accommodation. • We show that human accommodation is not driven correctly by defocus alone. • Accommodation is most efficient using changes in stimulus vergence with feedback.
Does Airbnb Disrupt the Private Rental Market? An Empirical Analysis for French Cities
2019
This article evaluates whether Airbnb rentals affect the rents in the private rental sector in eight cities in France. We estimate a hedonic equation for each city on individual data for apartments, allowing for heteroscedasticity and spatial error autocorrelation of unknown forms and using a large variety of structural and contextual characteristics of the apartments. We show that the density of Airbnb rentals puts upward pressure on rents in Lyon, Montpellier, and Paris, whereas it has no significant effect in other cities. If we restrict the analysis to the professional business of Airbnb rentals, which we define as the lodgings owned by an investor who rents either several “entire home…