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At least 1,459 records · Page 81Linked to original sources
PubMed2000

Coupling between molecular vibrations and liquid crystalline order parameters.

Specific Raman active modes in two prototype cyanobiphenyl liquid crystals are shown to display a temperature dependent softening proportional to either the nematic or smectic order parameters, while other vibrations (like the C identical withN stretch mode) remain unaltered. This selective coupling between intramolecular vibrations and the liquid crystalline order is related to the intrinsic symmetry of the modes. The method provides a simple, microscopic, noninvasive optical technique with which the liquid crystalline order parameters can be qualitatively mapped out.

Journal Article↗
PubMed2003

Entangling strings of neutral atoms in 1D atomic pipeline structures.

We study a string of neutral atoms with nearest neighbor interaction in a 1D beam splitter configuration, where the longitudinal motion is controlled by a moving optical lattice potential. The dynamics of the atoms crossing the beam splitter maps to a 1D spin model with controllable time dependent parameters, which allows the creation of maximally entangled states of atoms by crossing a quantum phase transition. Furthermore, we show that this system realizes protected quantum memory, and we discuss the implementation of one- and two-qubit gates in this setup.

Journal Article↗
PubMed1967

Cesar: cervical smear analyser and reader. A new approach to evaluating cells in cytological preparations.

Cesar presents an automated multiparameter approach to pattern recognition in the rapid detection of malignant cells from cervical and other cancers. Cells are cybernetically classified. They are collected into a container into which a nuclear stain may be incorporated and laid as a track on 35 mm. film using a disposable mapping pen device. The film track (Cytotrack) may be scanned using conventional optics and provision may be made for electronic sensing devices measuring a number of parameters, some of which are not normally used in conventional microscopy.

Cervix Uteri↗
PubMed1986

Interocular transfer in parallel visual pathways in pigeons.

Pigeons were trained to perform intensity, color and pattern tasks monocularly. After their training was completed, a unilateral electrolytic lesion was made either in the nucleus rotundus or in the nucleus opticus principalis thalami (OPT). The lesion was made in the trained hemisphere (contralateral to the trained eye) in half of the subjects and in the untrained hemisphere in the other half. After a 7-day recovery period the birds were retrained on the same tasks with the previously untrained eye. A rotundal lesion, on either side, resulted in the loss of interocular transfer of discrimination, whereas neither contralateral nor ipsilateral OPT lesions affected discrimination. These results suggest that the tectofugal visual pathway plays a crucial role in the interhemispheric transfer of visual information in pigeons.

Animals↗
PubMed1992

The pretectal complex of the rabbit: distribution of acetylcholinesterase and reduced nicotinamide adenine dinucleotide diaphorase activities.

The chemoarchitecture of the pretectal complex of the rabbit was examined in sections stained by acetylcholinesterase (AChE) and reduced nicotinamide adenine dinucleotide (NADH) diaphorase in the coronal, horizontal and sagittal plane. Twelve different subdivisions can be identified in the rabbit pretectum on the basis of the distribution of both histochemical markers. According to the standard terminology, the pretectal complex of the rabbit consists of: the nucleus of the optic tract; the anterior, posterior, olivary and medial pretectal nuclei; the nucleus of the posterior commissure; the periventricular subcommissural gray; the suprageniculate and internal suprageniculate nuclei, and the dorsal, lateral and medial terminal nuclei of the accessory optic system. The combined use of several sectioning planes and the histochemical mapping of AChE and NADH diaphorase have been of value in resolving the structural limits within transitional regions of the pretectum.

Acetylcholinesterase↗
PubMed2006

Influence of multiple scattering on three-dimensional imaging with optical diffraction tomography.

Optical diffraction tomography is an imaging technique that permits retrieval of the map of permittivity of an object from its scattered far field. Most reconstruction procedures assume that single scattering is dominant so that the scattered far field is linearly linked to the permittivity. In this work, we present a nonlinear inversion method and apply it to complex three-dimensional samples. We show that multiple scattering permits one to obtain a power of resolution beyond the classical limit imposed by the use of propagative incident and diffracted waves. Moreover, we stress that our imaging method is robust with respect to correlated and uncorrelated noise.

Journal Article↗
PubMed2004

Ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity.

We report an experimental demonstration of an ultracompact biochemical sensor based on a two-dimensional photonic crystal microcavity. The microcavity, fabricated on a silicon-on-insulator substrate, is designed to have a resonant wavelength (lambda) near 1.5 microm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n = 1.0 to n = 1.5. From observation of the shift in resonant wavelength, a change in ambient refractive index of delta(n) = 0.002 is readily apparent. The correspondence between absolute refractive index and resonant wavelength agrees with numerical calculation to within 4% accuracy. The evaporation of water in a 5% glycerol mixture is also used to demonstrate the capability for in situ time-resolved sensing.

Biosensing Techniques↗
PubMed2006

Observation of the developing optical continuum along a nonlinear waveguide.

We describe what is to our knowledge the first nondestructive measurement of the evolution of an optical continuum as a function of distance along a nonlinear waveguide. Spectral mapping is achieved on a subwavelength scale by utilizing near-field microscopy to probe the waveguide's evanescent field. The measured continuum broadening along the waveguide agrees in general form with predictions of broadening from theoretical calculations, but differs in some important details. Subwavelength resolution measurements are made both along and across the waveguide to reveal spectral variations not seen before by other techniques.

Journal Article↗
PubMed2001

Patients with persistent pain after enucleation studied by MRI dynamic color mapping and histopathology.

PURPOSE: To study possible causes of persistent pain in patients who underwent enucleation of the globe and in whom all other noninvasively detectable causes of pain had been ruled out. METHODS: Twenty patients were studied, 10 with intractable pain (score >5 on a 0-to-9 self-reporting pain scale) persisting for more than 6 months after enucleation (for various reasons) and 10 without pain (score <4) at least 6 months after enucleation. Magnetic resonance imaging (MRI) with dynamic color mapping (MRI-DCM) was used to quantify the motion of the optic nerve in millimeters per degree of gaze, 2 to 3 mm behind the implant. Histopathologic study of biopsy specimens was used to verify imaging findings. RESULTS: The optic nerve was attached to the implant in almost all (19/20) patients. On average, the motion was significantly less in patients with persistent intractable pain (0.04 mm/deg) than in patients without pain (0.08 mm/deg; normal orbit, 0.13 mm/deg). A biopsy specimen was available in 5 of 10 patients with persistent pain, and in 4 of those 5, microscopic neuroma was found close to the optic nerve-implant junction. CONCLUSIONS: In the enucleated orbit, the optic nerve is usually attached to the implant and soft tissue motion is decreased. In patients who have persistent pain after enucleation, motion is decreased even more, and a high percentage of microscopic amputation neuromas are found. Increased stiffness of orbital soft tissue and optic nerve attachment after enucleation are detectable using MRI-DCM, and may play a role in susceptible patients in the development of microscopic amputation neuroma and pain.

Adult↗
PubMedDate not supplied

[Three-dimensional computerized sonography in evaluation of the vascular system of the eye and orbit. I. Methodological approach and principles of analysis of results].

An examination of 40 healthy persons (80 eyes) enabled a refinement and unification of the ultrasound techniques applicable to investigations of a. ophthalmica, a. and v. centralis retinae, a. ciliaris brevis et longae and of other orbital space vessels. Abilities of various regimes of computer-based sonography, in particular of color energy Doppler mapping, were determined in examinations of capillary choroidal plexuses and of optic-nerve portions neighboring directly on the eyeball. The possibilities of using the three-dimension ultrasound angioreconstruction in examinations of the ocular angioarchitectonics and of the retrobulbar space were evaluated.

Adult↗
PubMedDate not supplied

Special report: Noninvasive multi-parameter functional optical imaging of the eye.

Advancement in the treatment of blindness depends on the development of new technologies that enable early detection, follow-up, and treatment of disease. The authors describe direct, noninvasive imaging of four parameters: blood flow, blood oximetry, metabolic state, and hidden vasculature, particularly capillaries. These are functional parameters of the retina known to be degraded by retinal disease. The new Retinal Function Imager (Optical Imaging, Ltd., Rehovot, Israel) can image all four parameters as intrinsic reflectance intensity differences over the retina's surface. During the past 2 decades, imaging of small optical signals has been a powerful tool for high-resolution functional mapping in the neocortex. In this article, this technology is applied to the retina and demonstrates a general tool for noninvasively probing retinal function in many modalities. Imaging functional changes before anatomic consequences arise holds promise as a powerful tool for early diagnosis and treatment of retinal disease.

Adult↗
PubMed1986

[Anatomy and development of the visual system of Pleurodeles poiretti].

After a deposit of HRP crystals in one eye of larval and adult Pleurodeles and the PAP immunocytochemical procedure, the organization of the visual system was described at stages 36, 45; 52 and postmetamorphic (according to Gallien and Durocher, 1975) and in the adult. At hatching stage, the retinopreoptic and the accessory pathways differentiate, soon after the retino-thalamico-pretectal pathway appears. The tectum differentiates later and a true retinotectal bundle can be seen only after the end of metamorphosis. In the whole, the pattern of the normal system is very simple in Pleurodeles especially as regard the ipsilateral fibres which never reach the tectum. This rudimentary organization lead us to conclude that the Pleurodeles and the Protopterus visual patterns are very similar.

Animals↗
PubMed1982

Retinal localization of scotomata by scanning laser ophthalmoscopy.

The scanning laser ophthalmoscope (SLO) system has been modified to permit direct retinal perimetry. A movable pinhole in a retinal conjugate plane furnishes a mapping stimulus whose retinal locus is directly observable on a video image of the fundus. Scotoma maps in patients with macular disease and physiologic scotomata associated with normal optic discs are presented. Clinical applications of the method are discussed.

Humans↗
PubMed1993

Gap junction density in human myometrium at term revealed by an anti-peptide antibody and laser scanning confocal microscopy.

The concept that the progesterone-estrogen ratio determines gap junction abundance in myometrium has developed from studies in laboratory animals. In the humans, however, gap junctions form in abundance at term despite a high progesterone-estrogen ratio. We have therefore examined the relationship between contractile activity, progesterone and estrogen levels and gap junction abundance in human myometrium at term. Myometrial tissue obtained from women who had an elective or emergency Cesarean operation at the 38th or 39th week of pregnancy was immunohistochemically examined using a polyclonal antiserum raised against a synthetic peptide matching part of the sequence of connexin43, the principal component of myometrial gap junctions. The concentration of progesterone and estradiol in the maternal blood was measured by means of radio-immunoassay. The number of gap junctions was estimated by counting of punctate staining patterns obtained in myometrial tissue as viewed by laser confocal microscopy and calculated per 1 microns 3 of tissue. The number of gap junctions measured was found to be related to the presence or absence of labor. In the myometrium of women in labor (active phase), the number of gap junctions was highest (45.25 +/- 35). When the myometrium was not contracting (non-labor) and when contractions were weak (pre-labor) the number of gap junctions was low (15.16 +/- 10-5.75 +/- 5). In the pre-and active phase of labor, the concentration of progesterone in maternal blood was significantly higher (P < 0.025 and 0.03, respectively) than in women who were not in labor. The present study shows the potential of using optical section series obtained by laser confocal microscopy for the quantification and mapping of the three-dimensional distribution of gap junctions in human myometrium at term.

Antibodies↗
PubMed1993

[Chronic idiopathic intestinal pseudo-obstruction: visceral myopathy. Report of 4 cases].

Chronic intestinal pseudo-obstruction is the term applied to a heterogeneous group of functional motility disorders sharing a common clinical expression: signs and symptoms of bowel obstruction in absence of mechanical occlusion. It is caused by ineffective intestinal propulsion. The chronic form of intestinal pseudo-obstruction may be primary or secondary. Primary pseudo-obstruction or chronic idiopathic pseudo-obstruction (CIIP) defines a group of propulsive disorders having no recognized underlying diseases. This study presents four female patients, aged between 4 months to 7 years, and makes a review of the literature. The symptoms, very similar in three of them, were bilious vomiting, abdominal distention and constipation, alternating with diarrhea and malnutrition. The fourth patient, different from the others in the age of onset and evolution, only had severe constipation and abdominal bloating. The diagnostic was made by full thickness biopsies during laparotomy, getting specimens by mapping, at different heights of intestine and stomach. Samples were studied by optic and electronic microscopy and visceral myopathies were found. None of them had urinary disorders. Medical treatment consisted of total parental nutrition and/or enteral nutrition. Cisapride was not effective in the two patients who received it.

Child↗