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At least 1,009 records · Page 56Linked to original sources
PubMed2000

A new face-mounted display system: pilot trial of clinical application in therapeutic endoscopy.

BACKGROUND AND STUDY AIMS: Since fiber endoscopes evolved into video endoscopes, there has been no remarkable progression in the optical system for endoscopy. The current optical system provided by fixed cathode-ray tube (CRT) display is a monitor-oriented system. In this study, we evaluate the practical usefulness of the face-mounted display (FMD), which provides us with an operator-oriented optical system. PATIENTS AND METHODS: The FMD device, weighing 110 g, is designed for consumer video home use, consisting of two active matrix liquid crystal color panels with 180,000-pixel resolution. With the picture-in-picture capability, FMD provided us with image-navigated endoscopic procedure. Fourteen patients were enrolled in this study; seven patients for endoscopic mucosal resection, two for insertion of an esophageal metallic stent, three for clipping for the bleeding and two for dilatation of anastomotic strictures. RESULTS: The FMD device allowed us to use an ultra large screen as if there has been a 62-inch screen 2 m ahead. During endoscopy, we could concentrate more on the procedures. There were no complications attributable to the use of the device. CONCLUSION: We are convinced of a new evolution in the optical system for therapeutic endoscopy with the FMD device.

Endoscopes, Gastrointestinal↗
PubMed2005

Optical limiter with an organic solution sandwiched between a polymer slab and a polymer grating.

An optical limiter was designed and fabricated. The device consists of an organic solution sandwiched between a polymer slab and a transparent relief polymer grating with a triangular groove. At low power the device has a high transmittance because the refractive index of the solution is matched with those of the slab and the grating materials and because the grating does not diffract. However, high power makes the organic solution thermally vaporize and makes the indices of the solution, slab, and grating materials become mismatched, which causes the grating to appear. The incident light is strongly absorbed, scattered, and self-defocused by the organic solution, and the grating suppresses the zero-order diffraction. Thus the transmitted light energy becomes lower than the damage threshold of human eyes or optical sensors. The device is an effective protection for human eyes or optical sensors against broadband pulsed-laser damage.

Journal Article↗
PubMed1999

Devic's neuromyelitis optica during pregnancy in a patient with systemic lupus erythematosus.

Neuropsychiatric forms of systemic lupus erythematosus (SLE) vary, most commonly consisting of seizures, psychiatric disturbances, or focal central nervous deficits. This is a new case of neuromyelitis optica or Devic's syndrome during the course of SLE. Few reports of this association exist in the literature. Our objective is to report this unique case of Devic's neuromyelitis optica during pregnancy in a patient with systemic lupus erythematosus. A 28-year-old woman had been diagnosed as having SLE with cutaneous and articular involvement in 1987 when she was 17 years old. She was treated with a synthetic antimalarial agent associated with corticosteroids. In 1994, during the fourth month of pregnancy, she had signs of transverse myelitis with a sensory level at T6 associated with an optic neuropathy suggesting a Devic's syndrome. The patient was managed by plasmapheresis sessions and intravenous corticosteroids. Transverse myelitis recurred postpartum and three years later at the same thoracic level. Management by bolus administration of a steroid and cyclophosphamide resulted in remission again. There have only been around a dozen reports in the literature of patients who had both Devic's neuromyelitis optica and SLE. Magnetic resonance imaging is contributive to diagnosis and therapeutic follow-up, showing spinal cord lesions with increased intensity on T2-weighted sequences. Although the clinical course of the present patient has been favourable so far, the prognosis of this neurologic disease is generally considered to be poor with elevated mortality.

Adrenal Cortex Hormones↗
PubMed2006

Optically driven resonance of nanoscale flexural oscillators in liquid.

We demonstrate the operation of radio frequency nanoscale flexural resonators in air and liquid. Doubly clamped string, as well as singly clamped cantilever resonators, with nanoscale cross-sectional dimensions and resonant frequencies as high as 145 MHz are driven in air as well as liquid with an amplitude modulated laser. We show that this laser drive technique can impart sufficient energy to a nanoscale resonator to overcome the strong viscous damping present in these media, resulting in a mechanical resonance that can be measured by optical interference techniques. Resonance in air, isopropyl alcohol, acetone, water, and phosphate-buffered saline is demonstrated for devices having cross-sectional dimensions close to 100 nm. For operation in air, quality factors as high as 400 at 145 MHz are demonstrated. In liquid, quality factors ranging from 3 to 10 and frequencies ranging from 20 to 100 MHz are observed. These devices, and an all-optical actuation and detection system, may provide insight into the physics of the interaction of nanoscale mechanical structures with their environments, greatly extending the viscosity range over which such small flexural resonant devices can be operated.

Colloids↗
PubMed2003

Element release from titanium devices used in oral and maxillofacial surgery.

Optical microscopy, scanning electron microscopy and X-ray microanalysis (EDS system) were used on c.p. titanium devices (21 grids and 10 plates) removed from 28 patients without signs of inflammation 6-24 months after surgery. Plates, grids and surrounding tissue were investigated to evaluate the titanium release and accumulation. Titanium was only present in the interfacial bone, probably due to fretting, and in all fibrous tissue surrounding the devices. Titanium content followed a decreasing gradient extending from the device surface and was not detected at a distance greater than 1mm. High titanium levels were found in blood cells in the connective tissue. In conclusion, titanium release from the devices stops only after bone is laid down on the titanium surfaces. Titanium release does not seem to interfere with the osteogenic process but perhaps may interact with it.

Bone Plates↗
PubMed2005

Spatially selective laser irradiation method controlled by real-time image analysis: optical aspects.

We present a spatially selective irradiation method for laser treatment of biological surfaces. The purpose is to irradiate only the pathological targets and to preserve the healthy surrounding parts. We are interested here in the optical arrangement of the device and in the evaluation of its physical limitations before it is used for medical purposes. The method uses real-time image analysis applied to the video imagery of the surface to be treated. The result of the image analysis generates the control signal to a spatial light modulator, allowing us to project an adequate repartition of laser irradiance on the surface to be treated. Experimental results demonstrate a spatial selectivity of approximately 10 microm for a 6.7 mm x 5 mm field. The optical system has no moving parts (unlike galvanometric scanners) and is able to irradiate multiple targets simultaneously with different doses.

Equipment Design↗
PubMed1988

Radiometric procedure for linearising computer-interfaced display systems.

Procedures for the adjustment of computer-interfaced display devices have been based on a subjective approach, generally relying on the visual examination of digital test patterns. The lack of an objective adjustment procedure means that the best image quality may not always be achieved. This paper describes how a simple home-made radiometer can be used to make screen luminance as well as density measurements on transparency film. The measurements are first used to determine the brightness and contrast settings for the display which enable the film to be used in the linear range of its optical densities. The display device characteristics, showing how luminance varies with grey level, are then determined. Using this information a simple display-linearising mapping can be produced to ensure that screen luminance (and hence film density) is a linear function of display grey-level value. Film-density measurements are also used to investigate the luminance and hence phosphor uniformity characteristics of the screen. The linearisation of the display device is an essential step in optimising the quality of recorded images. The measurements described are reproducible and sufficiently simple to provide the basis for a reliable quality-control procedure for the periodic assessment of the performance and settings of the display device.

Image Processing, Computer-Assisted↗
PubMed2000

A system for the study of visuomotor coordination during reaching for moving targets.

Prehensile behavior is a popular task in current research on human motor control. Most studies on reaching used stationary target objects and, therefore, most models do not address the challenges the motor system must respond to when reaching for moving objects. The machines used in earlier studies to produce object motion offered a limited range of trajectories and restricted control over various movement parameters. We have developed a device that allows a great variety of object trajectories along a flat-table surface and gives the experimenter full control over all movement parameters. A linear positioning system is used to move a sled beneath the table surface. Magnetic coupling transfers the sled's movement to the target object on the tabletop. This arrangement allows fast movements of the object (up to 5 m/s) and at the same time protects subjects from any harm due to the moving parts. The system is connected to LC shutter glasses, a 3-D movement registration device, and a switch that detects the onset of hand motion. This allows the selective withdrawal of vision during the reaching task or the introduction of changes in the object motion depending on the subject's reactions.

Electronic Data Processing↗
PubMed1986

[Premedication in fiber optic bronchoscopy from the patient's and the physician's viewpoint--a randomized study for the comparison of midazolam and hydrocodone].

To evaluate side effects and patients' assessment of fiberoptic bronchoscopy under local anesthesia, 122 consecutive patients answered questions from an outside interviewer (an experienced psychiatrist) and not from the endoscopists themselves. The effect of premedication with midazolam (5 mg i.m.) and hydrocodonum (15 mg i.m.) was compared in a randomized study. In a multiple choice questionnaire 68% of all patients indicated considerable fear in the days before bronchoscopy. They were more afraid of the possible diagnosis of cancer (23%) than of dyspnea or asphyxiation (14%). Coughing is considered the worst side effect of bronchoscopy by 25% of patients (36% of the endoscopists) followed by dyspnea during insertion of the scope (21%) and discomfort during local anesthesia. Although the patients premedicated with midazolam are more sedated (p = 0.025 by physicians' assessment vs. p = 0.11 in patients' view), they cough more (p = 0.001 vs. p = 0.22) and usually tolerate the examination less well (p = 0.009 vs. p = 0.08) than patients premedicated with hydrocodonum. 42% of patients premedicated with midazolam had anterograde amnesia. Although they did not remember all the unpleasant side effects, only 77% said they would repeat the procedure with the same premedication, compared with 90% of patients premedicated with hydrocodonum (p = 0.08). Before and two hours after premedication the reaction times had not changed (optical sign, Wiener reaction device) and were identical in the two patient groups. At that time 37% of the patients premedicated with midazolam and 27% of those premedicated with hydrocodonum were still sleepy and could not be regarded as fit for any form of travel.

Adult↗
PubMed2005

Optical coherence tomography imaging of the pancreas: a needle-based approach.

A novel, high-resolution, needle-based optical coherence tomography (OCT) device for improving the ability to detect early epithelial dysplasia in solid tissues/organs in vivo is currently in development. An instrument capable of real-time imaging of tissue microstructures in vivo could improve the ability to detect pathologic conditions such as dysplasia, and consequently improve patient outcomes. OCT is an emerging technology that can perform real-time cross-sectional imaging of tissue structures at micron-scale resolution in vivo. OCT has been shown to be effective in the imaging of luminal epithelium, capable of detecting epithelial dysplasia in Barrett's esophagus, and colonic polyps. However, OCT imaging depth with conventional probes is limited to the luminal surface (approximately 1-2 mm). The development of a technology and device that enables high-resolution, real-time imaging of solid tissues beyond 1- to 2-mm deep at or near the cellular level in vivo could improve the diagnosis of diseases of the pancreas and other solid organs.

Diagnosis, Differential↗
PubMed2000

COPA as an aid for tracheal intubation.

The purpose of this study is to verify the usefulness of the cuffed oropharyngeal airway (COPA) as a device to guide a tracheal tube using a semiblind technique with a lightwand. Ten anaesthetised patients (ASA I-II, aged 35-67) undergoing to an elective surgery were analysed. We selected and positioned a correct size of COPA for each patient. A lightwand (Trachlight) was then inserted into the COPA to confirm correct placement of this device. The lightwand was then removed and the first portion of a tube exchanger (TE) was inserted and connected by a 15-mm connector with the breathing circuit and its position was confirmed by End Tidal CO(2) values during ventilation. The patients were then paralysed and ventilation through the first portion of the TE reconfirmed. The COPA was removed, and the second portion of the TE was connected and used as a guide for a tracheal intubation. This combined technique had a success rate of six out of ten patients and could be used for airway management if a fibre optic scope or other devices such as a Combitube, LMA or LMA Fastrach were not available. The preliminary data from this study are not indicative of the statistical validity of this technique. Further studies should be performed to verify the statistical reliability of the technique.

Adult↗
PubMed1985

Optical fibre plethysmograph.

We describe a method for obtaining blood volume information from the external jugular vein or carotid artery by means of an optical fibre transducer. The device may be used to obtain accurate predictions of the state of the cardiac cycle, thereby enabling a range of physiological measurements to be made. The transducer is entirely non-invasive and non-magnetic; it is extremely robust and is unaffected by the electrically and magnetically hostile environment created by an NMR scanner.

Biomedical Engineering↗
PubMed2004

[The unexpectedly difficult airway -- a plea for the oxford-non-kinking-tube].

The skill to safely manage the unexpectedly difficult airway is expected from every anaesthetist. The strategies to safely overcome this severe problem have to be adapted to the given equipment and the individual aptitude and skills of the respective colleague. The algorithms for management of the difficult airway should be as simple as possible, and one cannot assume that devices for fibre-optic intubation are available at every site. Indispensable, however, is the availability of face masks, naso- and oropharyngeal airways and laryngeal mask airways in different sizes at each induction site. This paper is especially devoted to recalling the Oxford non-kinking tube and its specific way of handling, as a lot of cases of unexpectedly difficult airway can be safely managed with this tool. Alternatives to safeguarding the difficult airway are the intubation laryngeal mask airway or the esophago-tracheal combitube. For managing the worst case, the "cannot ventilate - cannot intubate" disaster, instruments for percutaneous punction of the trachea and devices for oxygen insufflation must be readily available in every theatre.

Humans↗
PubMedDate not supplied

The influence of formamide on thermal denaturation profiles of DNA and metaphase chromosomes in suspension.

Systematic photometric studies are presented to analyze the thermal denaturation behaviour with and without formamide of metaphase chromosome suspensions in comparison to DNA solutions. Temperature dependent hyperchromicity measurements at 256 nm and 313 nm were performed using an appropriately designed computer-controlled photometer device. Due to an upright optical axis, this allowed absorbance measurements with negligible sedimentation effects not only for solutions of pure DNA, but also for particle suspensions of isolated metaphase chromosomes. This device has a temperature resolution of +/- 0.5 degrees C and an optical sensitivity of 10(-3) to 10(-4) optical density. For calf thymus DNA the reduction of the melting point with the increase of formamide in the solution was measured at pH 7.0 and pH 3.2. The good correlation of the theoretical approximation to experimental data indicated the suitability of the apparatus to quantitatively describe DNA conformation changes induced by thermal denaturation. For metaphase chromosome preparations of Chinese hamster culture cells, absorbance changes were measured between 20 degrees C and 95 degrees C with a temperature gradient of 1 degrees C/min. These measurements were performed at pH 7.0 and at pH 3.2. The denaturation profiles (= first derivative of the absorbance curve) resulted in a highly variable peak pattern at 256 nm and 313 nm indicating complex conformation changes. A statistical evaluation of the temperature values of the peak maxima resulted in temperature ranges typical for chromosomal conformation changes during thermal treatment. Especially the range of highest temperature values was independent from pH modifications. For pH 3.2 the influence of formamide on the denaturation behaviour of metaphase chromosome preparations was analyzed. In contrast to pure DNA solutions, a reduction of the "melting point" (i.e. the maximum temperature at which a conformation change takes place) was not found. However, the denaturation behaviour depended on the duration of formamide treatment before the measurement.

Animals↗
PubMed2002

Photothermal properties of shape memory polymer micro-actuators for treating stroke.

BACKGROUND AND OBJECTIVES: In this paper the photothermal engineering issues of novel shape memory polymer (SMP) microactuators for treating stroke are presented. The engineering issues for using lasers to heat and subsequently actuate these SMP devices are presented in order to provide design criteria and guidelines for intravascular, laser activated SMP devices. MATERIALS AND METHODS: A total of three devices will be presented: two interventional ischemic stroke devices (coil and umbrella) and one device for releasing embolic coils (microgripper). The optical properties of SMP, methods for coupling laser light into SMP, heating distributions in the SMP devices, and the impact of operating the thermally activated material in a blood vessel are presented. RESULTS: Actuating the devices requires device temperatures in the range of 65-85 degrees C. Attaining these temperatures under flow conditions requires critical engineering of the SMP optical properties, optical coupling into the SMP, and device geometries. CONCLUSION: Laser-activated SMP devices are a unique combination of laser-tissue and biomaterial technologies. Successful deployment of the microactuator requires well-engineered coupling of the light from the diffusing fiber through the blood into the SMP.

Chemical Phenomena↗
PubMed2005

Observation of amplitude and phase in ridge and photonic crystal waveguides operating at 1.55 microm by use of heterodyne scanning near-field optical microscopy.

We apply heterodyne scanning near-field optical microscopy (SNOM) to observe with subwavelength resolution the amplitude and phase of optical fields propagating in several microfabricated waveguide devices operating around the 1.55 microm wavelength. Good agreement between the SNOM measurements and predicted optical mode propagation characteristics in standard ridge waveguides demonstrates the validity of the method. In situ observation of the subwavelength-scale distribution and propagation of optical fields in straight and 90 degrees bend photonic crystal waveguides facilitates a more detailed understanding of the optical performance characteristics of these devices and illustrates the usefulness of the technique for investigating nanostructured photonic devices.

Crystallization↗
PubMed2006

Photopolarimeter based on two gratings recorded in thin organic films.

A photopolarimeter based on two different kinds of diffraction gratings (a two-grating photopolarimeter) has been developed for real-time measurements of the four elements of the Stokes vector. The main elements of the device are a pure polarization grating and an ordinary transmission grating, both recorded by means of holographic techniques in thin films of organic materials. The first one consists of a diffraction grating recorded by two interfering opposite circularly polarized beams in a Langmuir-Blodgett film of an azo-compound material. The second component is a grating recorded by two interfering parallel circularly polarized beams in a thin film of a photosensitive polymer. Both gratings offer long time stability and good diffraction efficiency. Four photodiodes collect the first-order diffracted beams from these gratings, the output signals of which are read through an analog-to-digital converter by a PC. The optical alignment of the device is easy and the calibration is realized in a one-step procedure.

Journal Article↗
PubMed2003

Microassembly of semiconductor three-dimensional photonic crystals.

Electronic devices and their highly integrated components formed from semiconductor crystals contain complex three-dimensional (3D) arrangements of elements and wiring. Photonic crystals, being analogous to semiconductor crystals, are expected to require a 3D structure to form successful optoelectronic devices. Here, we report a novel fabrication technology for a semiconductor 3D photonic crystal by uniting integrated circuit processing technology with micromanipulation. Four- to twenty-layered (five periods) crystals, including one with a controlled defect, for infrared wavelengths of 3-4.5 microm, were integrated at predetermined positions on a chip (structural error <50 nm). Numerical calculations revealed that a transmission peak observed at the upper frequency edge of the bandgap originated from the excitation of a resonant guided mode in the defective layers. Despite their importance, detailed discussions on the defective modes of 3D photonic crystals for such short wavelengths have not been reported before. This technology offers great potential for the production of optical wavelength photonic crystal devices.

Crystallization↗