Search results for "Contrast"

Simultaneous Color Contrast in Goldfish— a Quantitative Study

1997

AbstractA set of 9–15 colored test fields was presented to goldfish. In Experiment 1, test field hues ranged from green through yellow to red; in Experiment 2, the hues varied from blue through gray to yellow. In the training conditions, the test fields were presented with a gray or black surround. The fish learned to choose one intermediate test field hue by rewarding them with food. In the test conditions, the color of the surround was changed from gray to green, or red (Experiment 1), and from black to blue, or yellow (Experiment 2). The choice behavior of the goldfish changed substantially: one of the test fields other than the training test field was preferred. Direction and strength o…

Influence of the type of illumination on the measurement of the modulation transfer function in the living human eye: A theoretical study

1999

Abstract Applications such as refractive surgery demand an objective appraisal of the retinal image quality. The modulation transfer function (MTF) provides that information when measured directly. Moreover, the MTF obtained using a simple and objective method such as that described in this paper allows the neural contrast sensitivity function (CSF) to be obtained from the global CSF and the MTF. When calculating the MTF it must be borne in mind whether the applicable theory is coherent or incoherent. In the literature, the developed theory presents some approximations and incongruities. Also, it is interesting to note that the method of recording the MTF (short or long time of integration,…

Enhanced detection of contrast regions in echocardiograms by adaptive quantization

2002

The statistics of ultrasound echo images are governed by Rayleigh statistics. The authors derive some experimentally verifiable predictions of this theory, compare them with experimental results obtained from echocardiographic images, and derive a new color coding scheme, (adaptive quantization) that is adapted to the signal-dependent noise predicted by theory. This results in some technical advantages and in an improved discrimination of regions of the echo image that are enhanced by echo contrast material. >

The strange case of Pomar family: the dangers of roads

2012

Many studies conducted on risk-related issues use quantitative methods. Questionnaires or formal interviews are applied to subjects to construct some attitude or particular opinion about their sense of security. Since the risk-perception theory has been brought from cognitive psychology, there is a biased assumption to think this issue should use these survey types of techniques. In contrast, this article proposes that risk as social construal should be studied according to qualitative analyses that explore the connection between variables. That women perceive more risks than men can be a of second-order explanation, appropriate for opinion polls or managerial policies, but not scientific a…

Neural interaction of retinal aftereffects and contrast adaptation in perception of gabor gratings

2010

Ossovenography and Epidural Venography

1976

Henning (1940) and Ehrhardt and Kneip (1943) were the first to report injection of contrast medium into bone. In 1952 Fischgold et al. reported that contrast injections into a human spinous process resulted in an outline of the venous plexus of the attached vertebral body. In subsequent years improvements have been made which now permit contrast visualization of the venous plexuses of the entire vertebral axis.

<title>Stereoacuity determination at changing contrast of colored stereostimuli</title>

2003

Studies are focused on design and appraisal of an objective test for assessment of the stereovision quality in unfavorable conditions. Stereostimuli of different colors are used while the contrast of one of the stimulus being varied. Tests are based on principles of black-and-white and two primary color random dot stereotests. Experiments are divided by the method of stimuli display and separation: 1) stereoeffect is obtained haploscopically - by use of spectacles with color filters (blue and red) or prisms, 2) stimuli separation is obtained by liquid crystal shutters when both eye stimuli are demonstrated with a different delay. The stereovision threshold is determiend at different stimuli…

Civilization and sexual abuse: selected Indian captivity narratives and the Native American boarding-school experience

2019

This paper offers a contrastive analysis of Indian captivity narratives and the Native American boarding-school experience. Indian captivity narratives describe the ordeals of white women and men, kidnapped by Indians, who were separated from their families and subsequently lived months or even years with Indian tribes. The Native American boarding-school experience, which began in the late nineteenth century, took thousands of Indian children from their parents for the purpose of “assimilation to civilization” to be facilitated through governmental schools, thereby creating a captivity of a different sort. Through an examination of these two different types of narratives, this paper reveal…

Synthesis and bio-functionalization of magnetic nanoparticles for medical diagnosis and treatment

2011

The synthesis of multifunctional magnetic nanoparticles (NPs) is a highly active area of current research located at the interface between materials science, biotechnology and medicine. By virtue of their unique physical properties magnetic nanoparticles are emerging as a new class of diagnostic probes for multimodal tracking and as contrast agents for MRI. Furthermore, they show great potential as carriers for targeted drug and gene delivery, since reactive agents, such as drug molecules or large biomolecules (including genes and antibodies), can easily be attached to their surface. On the other hand, the fate of the nanoparticles inside the body is mainly determined by the interactions wi…

Radiolabeling of DOTATOC with the long-lived positron emitter 44Sc.

2010

Abstract The positron-emitting radionuclide 44 Sc with a half-life of 3.97 h and a β + branching of 94.3% is of potential interest for clinical PET. As so far it is available from a 44 Ti/ 44 Sc generator in Mainz, where long-lived 44 Ti decays to no-carrier-added (nca) 44 Sc. The 44 Sc is a trivalent metal cation and should be suitable for complexation with many well established bifunctional chelators conjugated to peptides or other molecular targeting vectors. Thus, the aim of this work was to investigate the potential of 44 Sc for labeling of DOTA-conjugated peptides. DOTA-D-Phe 1 -Tyr 3 -octreotide (DOTATOC) was used as a model molecule to study and optimize labeling procedure. Reaction…