نتایج جستجو برای: threshold field

تعداد نتایج: 897852  

Introduction: Radiotherapy is a common treatment modality for patients with head and neck malignancies. As the nose lies within the field of radiotherapy of the head and neck, the olfactory fibers and olfactory receptors may be affected by radiation. The aim of this study was to evaluate changes in olfactory threshold in patients with head and neck malignancies who have received radiation to th...

Journal: :Investigative ophthalmology & visual science 2003
Andrew Turpin Allison M McKendrick Chris A Johnson Algis J Vingrys

PURPOSE To investigate the accuracy and precision of threshold estimates returned by two Bayesian perimetric strategies, staircase-QUEST or SQ (a Swedish interactive threshold algorithm [SITA]-like strategy) and ZEST (zippy estimation by sequential testing), and to compare these measures with those of the full-threshold (FT) algorithm. METHODS A computerized visual field simulation model was ...

Journal: :The Journal of General Physiology 1938
George Wald

1. The variation of threshold with field area was measured in fields homogeneous in rod-cone composition. At 15 degrees above the fovea, an increase in field diameter from 1 degrees to 5 degrees reduces the threshold sevenfold, at 25 degrees above the fovea tenfold. 2. These changes are shown to follow qualitatively from simple statistical properties of the retinal mosaic. Analytic treatment le...

Journal: :The British journal of ophthalmology 2003
P G D Spry C A Johnson A M McKendrick A Turpin

AIM Psychophysical strategies designed for clinical visual field testing produce rapid estimates of threshold with relatively few stimulus presentations and so represent a trade-off between test quality and efficiency. The aim of this study was to determine the measurement error of a staircase algorithm similar to full threshold with standard automated perimetry (SAP) and frequency doubling per...

Journal: :Biophysical journal 2006
J B Heng A Aksimentiev C Ho P Marks Y V Grinkova S Sligar K Schulten G Timp

We have explored the electromechanical properties of DNA on a nanometer-length scale using an electric field to force single molecules through synthetic nanopores in ultrathin silicon nitride membranes. At low electric fields, E < 200 mV/10 nm, we observed that single-stranded DNA can permeate pores with a diameter >/=1.0 nm, whereas double-stranded DNA only permeates pores with a diameter >/=3...

Journal: :Cardiovascular research 2006
Christian W Zemlin Sergey Mironov Arkady M Pertsov

OBJECTIVE The mechanism by which an electric field terminates arrhythmias continues to puzzle investigators. Existing experimental methods provide information about epicardial manifestations of electrical cardioversion, yet little is known about field effects deep inside the myocardium. Here we combine specially designed optical mapping experiments and computer modeling to separate the intra-my...

Journal: :Physical review letters 2006
Thomas Becher Matthias Neubert

Methods from soft-collinear effective theory are used to perform the threshold resummation of Sudakov logarithms for the deep-inelastic structure function F2(x,Q2) in the end-point region x-->1 directly in momentum space. An explicit all-order formula is derived, which expresses the short-distance coefficient function C in the convolution F2 = C multiply sign in circle phi q in terms of Wilson ...

1996
E. Calzetta B. L. Hu

We explore how the existence of a eld with a heavy mass in uences the low energy dynamics of a quantum eld with a light mass by expounding the stochastic characters of their interactions which take on the form of uctuations in the number of (heavy eld) particles created at the threshold, and dissipation in the dynamics of the light elds, arising from the backreaction of produced heavy particles...

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