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At least 307 records · Page 17Linked to original sources
PubMed2000

Adaptive Optics Imaging of the CLASS Gravitational Lens System B1359+154 with the Canada-France-Hawaii Telescope.

We present adaptive optics imaging of the CLASS gravitational lens system B1359+154 obtained with the Canada-France-Hawaii Telescope (CFHT) in the infrared K band. The observations show at least three brightness peaks within the ring of lensed images, which we identify as emission from multiple lensing galaxies. The results confirm the suspected compound nature of the lens, as deduced from preliminary mass modeling. The detection of several additional nearby galaxies suggests that B1359+154 is lensed by the compact core of a small galaxy group. We attempted to produce an updated lens model based on the CFHT observations and new 5 GHz radio data obtained with the MERLIN array, but there are too few constraints to construct a realistic model at this time. The uncertainties inherent with modeling compound lenses make B1359+154 a challenging target for Hubble constant determination through the measurement of differential time delays. However, time delays will offer additional constraints to help pin down the mass model. This lens system therefore presents a unique opportunity to directly measure the mass distribution of a galaxy group at intermediate redshift.

Journal Article↗
PubMed2001

Optical search for extraterrestrial intelligence with Air Cerenkov telescopes.

We propose using large Air Cerenkov telescopes (ACTs) to search for optical, pulsed signals from extraterrestrial intelligence. Such dishes collect tens of photons from a nanosecond-scale pulse of isotropic equivalent power of tens of solar luminosities at a distance of 100 pc. The field of view for giant ACTs can be on the order of 10 square degrees, and they will be able to monitor 10-100 stars simultaneously for nanosecond pulses of about 6th magnitude or brighter. Using the Earth's diameter as a baseline, orbital motion of the planet could be detected by timing the pulse arrivals.

Astronomy↗
PubMed2004

A telescope-design directional neutron spectrometer.

A directional spectrometer that uses a superheated emulsion of dichlorotetrafluoroethane at the centre of a 30 cm diameter moderating-sphere of nylon-6. The system has a telescope-design wherein the detector views a narrow solid angle of about 1/6 steradians. The hydrogenous sphere effectively attenuates laterally incident neutrons, thus providing a strong angular dependence of the response. The central detector is sequentially operated at seven temperatures between 25 and 55 degrees C in order to generate a matrix of nested response functions suitable for few-channel spectrometry. The response matrix of the system has been determined by calibrations with monoenergetic neutrons and by Monte Carlo neutron transport calculations. The double-differential unfolding method developed for this system applies the principle of maximum entropy and allows for the rigorous use of all a priori information. The spectrometer is intended for use in the mixed neutron/photon fields encountered in the nuclear power industry, being suitable for spatially distributed radiation sources with maximum neutron energies up to 10 MeV.

Anisotropy↗
PubMed2006

Space dosimetry with the application of a 3D silicon detector telescope: response function and inverse algorithm.

One of the many risks of long-duration space flights is the excessive exposure to cosmic radiation, which has great importance particularly during solar flares and higher sun activity. Monitoring of the cosmic radiation on board space vehicles is carried out on the basis of wide international co-operation. Since space radiation consists mainly of charged heavy particles (protons, alpha and heavier particles), the equivalent dose differs significantly from the absorbed dose. A radiation weighting factor (w(R)) is used to convert absorbed dose (Gy) to equivalent dose (Sv). w(R) is a function of the linear energy transfer of the radiation. Recently used equipment is suitable for measuring certain radiation field parameters changing in space and over time, so a combination of different measurements and calculations is required to characterise the radiation field in terms of dose equivalent. The objectives of this project are to develop and manufacture a three-axis silicon detector telescope, called Tritel, and to develop software for data evaluation of the measured energy deposition spectra. The device will be able to determine absorbed dose and dose equivalent of the space radiation.

Algorithms↗
PubMed2006

A solid state microdosimeter based on a monolithic silicon telescope.

A monolithic silicon telescope, consisting of a DeltaE and an E stage-detector ( approximately 1.9 microm and 500 microm thick, respectively), was coupled to a polyethylene converter in order to investigate the feasibility of a solid state microdosimeter with respect to the field-funnelling effect. This work discusses the preliminary results of an analytical approach for the correction of a spectrum measured with this silicon-based microdosimeter for tissue-equivalence and geometrical effects. The device was irradiated with 2.7 MeV monoenergetic neutrons at the INFN-Laboratori Nazionali di Legnaro (Legnaro, Italy). The non tissue-equivalence of silicon was corrected by exploiting the signals generated in the E-stage. The correction for the sensitive volume geometry was optimised by taking into account the track length distribution of the recoil-protons generated in the converter. The derived dose distribution of the energy imparted per event was compared to the one measured with a cylindrical tissue-equivalent proportional counter (TEPC). The agreement is satisfactory.

Computer-Aided Design↗
PubMed1984

Esophageal atresia. Prognostic factors and contribution of preoperative telescopic endoscopy.

In recent years, the surgical correction of esophageal atresia with distal tracheoesophageal fistula (TEF) has become increasingly successful. However, there remains a group of high-risk patients with specific anatomical abnormalities in whom the mortality remains appreciable. These associated disorders include cardiac, renal, and chromosomal anomalies as well as severe respiratory distress syndrome. These factors, rather than low birth weight or early gestational age, are primarily responsible for surgical mortality. Preoperative telescopic bronchoscopy has been a useful adjuvant confirming the diagnosis, identifying unusual variants, and permitting the proper anatomic placement of the endotracheal tube. A Fogarty balloon catheter can be passed bronchoscopically into the distal TEF in patients with severe respiratory distress syndrome to occlude the fistula and facilitate effective positive pressure ventilation. Thirty-two patients were treated for esophageal atresia among whom 28 had esophageal atresia with distal TEF, three had esophageal atresia alone, and one had esophageal atresia with proximal TEF. The higher-risk group comprised those with severe respiratory insufficiency as evidenced by a room air paO2 of less than 60 mmHg; this group accounted for nine of the ten deaths in the total series. There was one late death following surgical correction. In summary, in the absence of severe respiratory insufficiency or associated life-threatening congenital anomalies, the results of surgical correction for esophageal atresia are remarkably good and survival in this group approximates 100%.

Abnormalities, Multiple↗
PubMed2001

Accuracy of delayed cultures of plugged telescoping catheter samples for diagnosing bacterial pneumonia.

OBJECTIVE: It is not always feasible to culture immediately bacteriologic samples of protected pulmonary specimens on a 24-hr basis before starting antibiotic treatment. We have evaluated the effect of delaying the culture of immediate plugged telescoping catheter (PTC) samples performed before starting antibiotherapy. DESIGN: Prospective paired comparisons study. SETTING: Intensive care unit in a university hospital. PATIENTS: Ninety-nine PTCs were performed on 68 intensive care unit patients suspected of nosocomial or community- acquired bacterial pneumonia. INTERVENTION: PTC samples were divided into two aliquots: one for immediate (H0) analysis and one for storage at 4 degrees C (H24) for 24 hrs before being cultured. MEASUREMENTS AND MAIN RESULTS: The results from these delayed cultures (H24) were compared with those from immediate ones (H0). All negative H0 samples (n = 59) were also negative at H24. Forty PTCs yielded one or more microorganisms, with a total of 69 microorganisms in one or both samples. H0 and H24 cultures were concordant in 119 of 128 (97.9%) cases (kappa coefficient value 0.79) with a threshold of 103 colony-forming units (cfu)/mL. Agreement between paired cultures was very good. The bias calculated as the mean difference between paired culture results was 0.128 +/- 1.024 (Deltalog). Concordance using the 103 cfu/mL threshold (102/107 cases, kappa coefficient value 0.82) and agreement were enhanced (0.067 +/- 0.645) when possible contaminants were excluded (n = 21). CONCLUSIONS: Storing PTC specimens for 24 hrs at 4 degrees C is an acceptable alternative when culturing cannot be performed immediately. This allows starting antibiotic treatment without any delay.

Adult↗
PubMed1999

Treatment of fractures of femur and tibia with the telescopic locking nail: design of a new implant and the first clinical results.

BACKGROUND: This study was carried out to evaluate the first clinical experiences with the telescopic locking nail (TLN). The TLN is a newly developed universal locking nail system for both femur and tibia that permits cyclic dynamic loading at the fracture site while weightbearing. The nail can also be used for static interlocking or for compression of the fracture elements. The nail is strong enough to permit immediate weightbearing, and the diameter of 9 mm allows unreamed introduction in many cases. MATERIALS: Seventy-one consecutive patients were treated with the TLN, 24 patients with femoral and 47 patients with tibial fracture or nonunion. RESULTS: Functional outcome, complication rate, and union rate were comparable to other interlocking nail systems. CONCLUSION: Its distinctive biomechanical properties and its universal application in both femur and tibia make the TLN a sophisticated, yet in practice simple, new asset in the practice of intramedullary nailing.

Adolescent↗
PubMed1999

Endoscope-assisted surgery for acoustic neuromas (vestibular schwannomas): early experience using the rigid Hopkins telescope.

OBJECTIVE: Endoscopes have been increasingly used during neurosurgical procedures. Previously, they have been shown to offer better visualization than the microscope in selected situations and frequently have allowed less invasive surgery. This study was undertaken to determine whether endoscopy is safe and effective during suboccipital surgery for vestibular schwannomas. METHODS: Ten patients with vestibular schwannomas underwent suboccipital transmeatal craniotomies for tumor excision. Endoscopy with a rigid glass lens endoscope (Hopkins telescope) was used during tumor removal to examine posterior fossa neurovascular structures and after tumor excision to inspect the internal auditory canal. RESULTS: Complete tumor excision was achieved in nine patients. Endoscopy allowed improved identification of tumor and adjacent neurovascular relationships in all cases without the need for significant retraction of the cerebellum or brain stem. In addition, residual tumor at the fundus of the internal auditory canal (n = 2) and exposed petrous air cells (n = 3) not seen with the microscope were identified endoscopically. Operative time was not significantly increased by incorporating the endoscope. CONCLUSION: Posterior fossa endoscopy can be performed safely during surgery for tumor removal. Endoscope-assisted surgery for vestibular schwannomas may offer some advantages over standard microsurgery in selected cases. The advantages may include improved visualization, more complete tumor removal, and a lowered risk of cerebrospinal fluid leakage.

Adult↗
PubMed1976

Fields of view as they relate to the magnification of a telescope: a clarification.

The manufacturers of telescopic instruments typically describe their products in terms of the magnification produced. Most include some reference to the "object field" or the "acceptance angle," i.e., the angle subtended by the entrance port at the center of the entrance pupil. This paper considers varied factors utilized for calculating magnification and object field and proposes expressing the object field in terms of prism diopters rather than degrees.

Eyeglasses↗
PubMed1976

Telescopic lenses and driving.

In some states, persons with significantly reduced visual acuity are being licensed to drive while wearing telescopic spectacle lenses (TSL). In order to evaluate possible visual field limitations present with these devices, the peripheral visual fields of a group of normally sighted subjects were measured while they wore TSL. Severely restricted central fields and sizeable ring scotomas were present with all units tested. These result indicate that driving with TSL should be discouraged.

Accidents, Traffic↗
PubMed1981

Reversed telescopes on visual efficiency scores in field-restricted patients.

Low vision aids have not been successfully prescribed for many people with peripheral visual field loss. Visual field and visual acuity measurements for four field-restricted subjects were made with and without field-expanding reversed telescopes. The calculated visual efficiency was not significantly improved with such devices; therefore, their value remains in question.

Glaucoma↗
PubMed1987

Telescopic scanning and age-related maculopathy.

We report the management of various aspects of the care provided over a span of 12 years for a patient with age-related maculopathy (ARM). The use of a low-power telescope proved to be particularly helpful because, with it, she learned eccentric viewing and made best use of her remaining vision.

Aged↗
PubMed1989

Behind the lens telescope: a new concept in bioptics.

A new concept in bioptic prescriptions is presented. The new Behind-The-Lens (BTL) telescope provides the advantages of the typical bioptic with the additional advantage of providing a more acceptable appearance.

Adolescent↗
PubMedDate not supplied

Telescopic eyepieces in indirect ophthalmoscopy.

A new attachment that can be used with optimized ophthalmoscopes is described. Readily removable and interchangeable eyepieces containing small, lightweight Galilean telescopes approximately double the magnification. The influence of this device on some of the optical properties of binocular indirect ophthalmoscopy including magnification, field of view, brightness of the fundus image, and stereopsis, are reviewed briefly.

Humans↗
PubMed2004

T12-L1 telescoped chronic dislocation treated by en bloc one-piece spondylectomy and spine shortening.

The author presents a case in which a severe chronic thoracolumbar kyphotic posttraumatic deformity was corrected by a one-block spondylectomy with spine shortening, using a posterior approach. A 19-year-old paraplegic woman was admitted with a chronic deformity of the thoracolumbar spine due to a telescoped posterior dislocation of L1 on T12, which had occurred 8 months earlier. Single reduction by axial traction was impossible. Surgical correction was achieved by means of a total, one-block, L1 spondylectomy and end-to-end apposition of the T12 inferior platform onto the L2 superior platform. This was performed through a posterior approach. The reduction was fixed by a pedicular instrumentation extended from T10 to L4. To our knowledge, this is the first documented case in which the spondylectomy was performed in a single block including the vertebral body and posterior arch in the same piece. Five years following surgery, the clinical result is excellent with complete correction of the deformity and solid interbody vertebral fusion. The complete transection of the spinal cord permitted this aggressive approach, which would have not been possible in other types of pathology.

Adult↗
PubMed2006

The Implantable Miniature Telescope for macular degeneration.

PURPOSE OF REVIEW: The function is described of the Implantable Miniature Telescope, which is completing clinical development for bilateral end-stage macular degeneration, and 6-month results of the Phase II/III IMT002 prospective, multicenter study are presented. Multispecialty patient management and implications of the study's findings are discussed. RECENT FINDINGS: No medical treatments are currently available for bilateral end-stage age-related macular degeneration (atrophic or disciform scar age-related macular degeneration). The visual prosthetic device discussed in this update is implanted in the posterior chamber to reduce the impact of the scotomata on the patient's central vision. The goal of treatment is to improve the patient's ability to perform everyday activities and participate in roles and hobbies that impact their quality of life. Patients implanted with the device experienced clinically significant gains in visual acuity and quality of life at 6 months. In total, 89% gained two or more lines of best-corrected near or distance visual acuity. The device was generally safe and well tolerated. The surgical technique is important to minimize surgically related reduction in endothelial cell density. SUMMARY: This age-related macular degeneration visual prosthesis has been shown to improve visual acuity and quality of life for the bilateral end-stage age-related macular degeneration patient population that at present has no other acceptable options. Endothelial cell density from baseline to 6 and 12 months after device implantation was reduced due to trauma from the surgical procedure, but was compatible with a healthy cornea. Meticulous surgical technique and a comprehensive, multispecialty approach to preoperative and postoperative patient management are essential for successful outcomes.

Clinical Trials as Topic↗