Sunday, January 25, 2015



Soy un nuevo usuario

Olvidé mi contraseña

Entrada usuarios

Lógica Matemáticas Astronomía y Astrofísica Física Química Ciencias de la Vida
Ciencias de la Tierra y Espacio Ciencias Agrarias Ciencias Médicas Ciencias Tecnológicas Antropología Demografía
Ciencias Económicas Geografía Historia Ciencias Jurídicas y Derecho Lingüística Pedagogía
Ciencia Política Psicología Artes y Letras Sociología Ética Filosofía

rss_1.0 Clasificación por Disciplina

Nomenclatura Unesco > (22) Física > (2209) Óptica
(2209.01) Espectroscopía de absorción (2209.02) Cinematografía
(2209.03) Colorimetría (2209.04) Espectroscopía de emisión
(2209.05) Fibras ópticas (2209.06) Óptica geométrica
(2209.07) Holografía (2209.08) Iluminación
(2209.09) Radiación infrarroja (2209.10) Láseres
(2209.11) Luz (2209.12) Microscopios
(2209.13) Óptica no lineal (2209.14) Propiedades ópticas de los sólidos
(2209.15) Optometría (2209.16) Instrumentos fotográficos
(2209.17) Fotografía (2209.18) Fotometría
(2209.19) Óptica física (2209.20) Radiometría
(2209.21) Espectroscopía (2209.22) Radiación ultravioleta
(2209.23) Radiación visible (2209.24) Física de la visión
(2209.90) Tratamiento digital. Imágenes (2209.99) Otras (especificar)

Categorías relacionadas:
(3311.11) Instrumentos ópticos

Mostrando recursos 1 - 20 de 25,821

1. Visual interhemispheric transfer to areas 17 and 18 in cats with convergent strabismus - Chantal Milleret; Jean-christophe Houzel
recordings Commissural connections between primary visual cortical maps of the two hemispheres are essential to unify the split representation of the visual ®eld. In normal adult cats, callosal connections are essentially restricted to the border between areas A17 and A18, where the central vertical meridian is projected. In contrast, early convergent strabismus leads to an expanded callosal-receiving zone, as repeatedly indicated by anatomical experiments. We investigated here the functional correlates of this widespread distribution of callosal terminals by analysing transcallosal visual responses in ®ve anaesthetized and paralysed 4± 10-month-old cats whose right eye had been surgically deviated on postnatal day...

2. Impairment of - Olaf Stanger; Martin Weger; Rima Obeid; Werner Temmel; Andreas Meinitzer; Otto Schmut
homocysteine metabolism in patients with retinal vascular occlusion and non-arteritic ischemic optic neuropathy

Electro-optic techniques are becoming increasingly im-portant in ultrafast electron bunch longitudinal diagnostics and have been successfully implemented at various acceler-ator laboratories. The longitudinal bunch shape is directly obtained from a single-shot, non-intrusive measurement of the temporal electric field profile of the bunch. Further-more, the same electro-optic techniques can be used to measure the temporal profile of terahertz / far-infrared opti-cal pulses generated by a CTR screen, at a bending magnet (CSR), or by an FEL. This contribution summarizes the re-sults obtained at FELIX and FLASH.

4. C. Vázquez, MEMBER SPIE - J. Montalvo; P. C. Lallana; Iii Madrid; Dpto Tecnologı́a
SRadio-frequency ring resonators for self-referencing fiber-optic intensity sensors

While action potentials are the usual means of transmission in axons, recent work has established that decrementally conducted potentials are also utilized. Decremental

Purpose: Oxidative damage is implicated in retinal ganglion cell (RGC) death after optic nerve transection (ONT) and in glaucoma. We analyzed the expression and protective effects of thioredoxins (TRXs), regulators of the cellular reduction-oxidative (redox) state, in RGCs damaged by pharmacologically induced oxidative stress, ONT, and elevated intraocular pressure (IOP). Methods: ONT and glaucoma models in the rat were used. The glaucoma model was generated in albino rats by intracameral injection of india ink followed by ab externo laser applications to the pigmented trabecular band. Retrograde labeling of RGCs was performed with dextran tetramethylrhodamine. RGC isolation from rat retinas was...

7. 1 Color and polarized light vision: The Drosophila retinal mosaic - Claude Desplan Biology; Claude Desplan; Claude Desplan Biology
Although the types of eyes found across the animal kingdom vary extensively in general organization and complexity, all visual systems use similar mechanisms to respond to environmental cues. In particular, all animals use related opsin photopigment proteins in their photoreceptor cells to capture photons (for review, see Arendt & Wittbrodt 2001). The visual system serves several major purposes. At the origin, it likely served as a light detector for photophobic or photophilic behaviors. It then rapidly acquired an additional function as a light detector for entraining the circadian clock. These uses did not require complex optics or sophisticated neural processing,...

8. Findings in a patient with herpes simplex viral meningitis associated with acute retinal necrosis syndrome - Yukiko Tada; Kiyoshi Negoro; Mitsunori Morimatsu; Hajimu Makino; Teruo Nishida
clinical findings of viral meningitis associated with acute retinal necrosis syndrome in his right eye. MR images showed right optic nerve enlargement and high-intensity signal abnormalities in the region of the left lateral genic-ulate body and the left occipital lobe. Acute retinal necrosis (ARN) syndrome usually affects healthy adults. It involves the acute onset of diffuse uveitis, occlusive retinal vasculitis, vitri-tis, and rapidly progressive retinal necrosis (1). At end-stage, the syndrome often causes retinal de-tachment, optic atrophy, and severe visual loss. The origin of the syndrome is thought to be intraocular infection caused by varicella zoster virus (VZV) or herpes...

9. Planar Lightwave Circuits 11 4.2.5 Thermal Wavelength-selective Switch Based on Micro-ring Resonators - D. H. Geuzebroek
Abstract A thernally driven wavelength-selective switch, based on integrated-optic micro-ring resonators is described. This configuration allows high ON/OFF ratios combined with small dimensions. Measurements of the thermal behaviour ofa single resonator confirm the switching capability.

10. Practical Visualization of Internal Structure of White Matter for Image Interpretation: Staining a Spin-Echo T2-Weighted Image with Three Echo-Planar Diffusion-Weighted Images - Hajime Tamura; Shoki Takahashi; Noriko Kurihara; Shogo Yamada; Jun Hatazawa; Toshio Okudera
has been developed to visualize white matter fiber tracts with diffusion-weighted MR imaging. The purpose of this study was to determine whether superposition of a spin-echo T2-weighted image and a color-coded image derived from three orthogonal diffusion-weighted images could show fiber tract architecture of the brain with an image quality appropriate for accurate reading with a computer monitor. METHODS: MR images from 50 consecutive cases were reviewed. Three diffusion-weighted images per section were acquired with three orthogonal motion-probing gradients. These images were registered to a corresponding spin-echo T2-weighted image. A color-coded image was synthesized from three diffusion-weighted images by assigning...

11. lappe/e mlappe.htm - Antje Grigo; Frank Bremmer; Harald Frenz; Rene J. V. Bertin
Among the sensory signals available to control driving (or walking), the induced visual motion pattern, the optic flow, is a powerful source of information. The role of optic flow in visual navigation has been increasingly researched over the last ten years. The basic questions are: which information can be obtained from the optic flow, and how does the human visual system do it? I will concentrate on two tasks for which optic flow analysis can be used during driving. The first is the perception of heading (the direction of self-motion) from optic flow. The second concerns the perception of driving...

12. Spatial Alignment over Retinal Scotomas - Michael D. Crossl; Peter J. Bex
PURPOSE. Perceptual completion can mask the presence of physiological and pathologic retinal scotomas. This psycho-physical study used a spatial alignment task to examine the processes underlying this perceptual completion. Similarities between the completion of pathologic and physiological sco-tomas would be consistent with large-scale reorganization of the visual system in eye disease METHODS. In five control subjects with no eye disease, Vernier alignment thresholds were measured over the physiological blind spot at the optic nerve head and over equally eccentric temporal retina. For nine subjects with retinal scotomas, align-ment thresholds were measured over the maximum vertical extent of the larger scotoma...

13. Serial Follow-Up in Traumatic Optic Neuropathy Using Scanning Laser Polarimetry and Visual Field Testing
A 40-year-old male patient suffered from traumatic optic neuropathy in his right eye. Scanning laser polarimetry was arranged at 2 weeks, 9 weeks, 13 weeks, 24 weeks, and 34 weeks after the trau-ma. Manual or automated visual field testing was also arranged at 1 week, 5 weeks, 16 weeks, and 28 weeks correspondingly. The data revealed using scanning laser polarimetry (program GDx®, version 1.0.05; Laser Diagnostic Technologies, San Diego, Calif, USA) were nearly normal at 2 weeks after trauma, but lower visual field loss was revealed using visual field testing within 2 weeks after the trauma. The superior hump of...

14. Multifocal versus monofocal intraocular lenses after cataract extraction - Calladine,Daniel; Evans,Jennifer R.; Shah,Sweata; Leyland,Martin
BACKGROUND: Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL) implantation. Near vision, however, still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal) IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs. OBJECTIVES: The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses in people...

15. Síndrome de Sjögren-Larsson: tomografía de coherencia óptica y una nueva mutación - Burgueño Montañés, C.; García-Fernández, Miriam; Colunga Cueva, M.; García López, A.
Case report: A case is presented of a 30-year-old male with ichthyosis, mental retardation, epilepsy and spasticity. Ocular examination showed a best-corrected visual acuity of 0.5 and bilateral crystalline maculopathy. Optical coherence tomography (OCT) revealed focal hyperreflective spots and intrafoveal microcystoid spaces. The diagnosis of Sjögren-Larsson syndrome (SLS) was made, and confirmed by genetic analysis. Discussion: SLS is caused by mutations in the ALDH3A2 gene. A previously unreported novel mutation was identified, c.681-14T> G. Macular OCT makes it possible to find even funduscopy invisible changes. Its use is important because the OCT features of SLS are specific and, therefore, it can help to diagnose this rare systemic disease.

16. Ambliopía secundaria a quiste de iris - López-Arroquia, E.; Avendaño-Cantos, E.M.; Mesa-Varona, D.; Gálvez-Martínez, J.; López Romero, S.; Nuñez Plasencia, R.; González del Valle, F.
Caso clínico: Varón de 5 años de edad con ambliopía anisometrópica meridional secundaria a quiste de epitelio pigmentario de iris. Es evaluado mediante biomicroscopia ultrasónica (BMU) y tomografía de coherencia óptica de polo anterior (OCT Visante). Discusión: La OCT de polo anterior, aunque con limitaciones, es una herramienta útil en la evaluación de lesiones de polo anterior. Puede ser preferible, en la infancia, a la BMU

17. La forma de la pupila en el reino animal: de la pseudopupila a la pupila vertical - González Martín-Moro, Julio; Gómez Sanz, Fernando J.; Sales-Sanz, A.; Huguet, Eduardo; Murube del Castillo, Juan
Objective: To study the different pupil shapes adopted by the different animal species. Material and methods: Review of the related literature, using PubMed database. The initial search strategy was pupil shape (limited to animals). The first volume of System of Ophthalmology (Duke-Elder) and Evolution's witness (I. Schwab) were also reviewed. Results: An optic illusion called pseudopupil is usually observed in the compound eyes of insects. The pupil is circular in most vertebrates, however slit vertical pupils are present in cats and in some snake species. Vertical pupils could have a photoprotective function, as it makes a more complete closure possible in photopic conditions, and helps to camouflage the...

18. Cambios morfológicos y morfométricos en los capilares del nervio óptico de rata en un modelo experimental de glaucoma - Moreno, M.; Ríos, M. C.; Alba, C.; Díaz, Florentina; Villena, A.; Figueroa-Ortiz, L.C.; García Campos, J.
Aim: To study the morphological and morphometric changes produced in the capillaries of the optic nerve (ON) head and initial portion after the experimental increase in intraocular pressure (IOP). Material and methods: Wistar rats underwent cauterization of three episcleral veins, which produced an immediate increase in the IOP, and was maintained for 3 months. Sagittal sections ofthe eyeball were studied with immunohistochemicaltechniques, using a primary antibody to GLUT-1. The GLUT-1 positive capillaries were counted, and measurements were made of the area, perimeter and mean diameter. Results: Microscopic examination of sections of the ON of control rats revealed a lower density and larger caliber of capillaries in the prelaminar region...

19. The distribution of vasotocin and mesotocin immunoreactivity in the hypothalamic magnocellular neurosecretory nuclei of the Saharan herbivorous lizard, Uromastix acanthinurus Bell, 1825 (Sauria-Agamidae) - Barka-Dahane, Zohra; Bendjelloul, Mounira; Estabel, Jeanne; Exbrayat, Jean Marie
An immunohistochemical study of the magnocellular neurosecretory nuclei was performed in the hypothalamus of the desert lizard Uromastix acanthinurus using polyclonal antibodies against arginine vasotocin (AVT), mesotocin (MST) and neurophysins I and II (NpI, NpII). AVT- and MST-immunoreactivities were localized in individual neurons of the supraoptic, periventricular, and paraventricular nuclei and in scattered neurosecretory cells. The supraoptic nuclei (SONs) can be subdivided into rostral, medial and caudal portions. The rostral portion of the SONs was called the SON-ventral aggregation (V SON) because the neurosecretory neurons are present in the ventral part of the hypothalamus along the optic chiasma (OC). Their...

20. Toxic Effects of Combined Molecule from - Diflubenzuron On Paramecium Caudatum; Rouabhi Rachid; F. Z. Saci; H. Berrebbah; M. R. Djebar
Abstract: The struggle against the agricultural ravagers was increased in few last years; many products were appeared and destined to kill the harmful insects, of which we did not know their effects on ecosystem and non-target animals. In present work, we try to investigate the ecotoxicological effects of a combined molecule from Novaluron and diflubenzuron; two Insect growth Regulator (IGR) pesticides, on ecosystem and biomasses by the estimation of the growth and respiratory metabolism of Paramecium caudatum as a non-target aquatic organism exposed to these pesticides. The pesticides are tested in vitro by the addition of four concentrations (5,10,15 and...

Página de resultados:

Busque un recurso