Artur J Martins

Learn More
Prior work had shown that smooth eye movements depend both on the motion of the target on the retina and on the subject's expectations about future target motion (Kowler and Steinman, 1979a,b). Effects of expectation cannot be eliminated by making target motions unpredictable (Kowler and Steinman, 1981). The experiment reported here shows that effects of(More)
Rotational eye and head movements were recorded with great precision with scleral and cranial search coils in a rotating magnetic field. Compensatory eye movements were recorded in light and darkness during active as well as passive head movements in the frequency range 0.33-1.33 Hz. From the recorded, nominal gaze movements the effective gaze was(More)
This paper reviews advances in our knowledge about the stability of the human being's line of sight while fixating objects stationary with respect to himself. Recent technological developments made it possible to measure gaze with a high degree of accuracy when the head was free of artificial support. Measurements made with the head free while the subject(More)
Accurate recordings of eye movements of children 4 and 5 years old show that their eye movements differed from those of adults. During maintained fixation, saccades were large (1 degree to 2 degrees) and smooth eye movement speeds were high (45 minutes of arc per second). Saccade latencies were highly variable during target step tracking. Smooth pursuit(More)
Subjects used smooth eye movements to track small-amplitude sinusoidal target motions. Target frequencies (0.05 to 5 Hz) and amplitudes (1.9 to 30 min of arc) were in the range of those found in the retinal image during fixation of a stationary target while the head is not artificially supported. Smooth pursuit was poor at high target frequencies in several(More)
Health care workers are attributed to the group at highest risk of occupationally acquired bloodborne diseases as the result of contact with blood and body fluids. A cross sectional study was conducted between November 2009 and February 2010 in the North of Portugal, to identify potential risk factors for needlestick and sharps injuries. A questionnaire was(More)
Laparoscopy is a technique used in various surgical procedures. Few studies in the literature compare stress between laparoscopic and open surgery used for esophagogastric surgical procedures. Pulmonary function is known to be significantly affected in open surgeries, increasing postoperative morbidity and mortality. The current study aimed to assess(More)
Coumarin derivatives used as pesticides may accumulate in hydrophobic microstructures, such as biological membranes, aggregates of humic and fulvic acids, and micelles of pollutant surface active agents. In this work, w e present a comparison of three photophysical methods for the determination of the membrane-water and micelle-water partition constants,(More)
Carbon based films can combine the properties of solid lubricating graphite structure and hard diamond crystal structure, i.e., high hardness, chemical inertness, high thermal conductivity and optical transparency without the crystalline structure of diamond. Issues of fundamental importance associated with nanocarbon coatings are reducing stress, improving(More)