What the Longest Exposures from the Hubble Space Telescope Will eveal.

Detailed simulations are presented of the longest exposures on representative fields that will be obtained with the Hubble Space Telescope, as well as predictions for the numbers and types of objects that will be recorded with exposures of different durations. The Hubble Space Telescope will reveal the shapes, sizes, and content of faint, distant galaxies and could discover a new population of Galactic stars.

A simple model for neutrino cooling of the large magellanic cloud supernova.

A simplified analytic model of a cooling hot neutron star, motivated by detailed computer calculations, describes well the neutrinos detected from the recent supernova in the Large Magellanic Cloud. The observations do not require explanations that invoke exotic physics or complicated astrophysics. The parameters in this simple model are not severely constrained: 6.1(-3.6)(+3.5) x 10(52) ergs emitted in electron antineutrinos, a peak temperature of 4.2(-0.8)(+1.2) megaelectron volts, a radius of 27(-15)(+17) kilometers, and a cooling time of 4.5(-2.0)(+1.7) seconds.

Fiberoptic endoscope usage for intracanal visualization.

A new method of magnified intracanal visualization using a fiberoptic endoscope has been developed for use in conventional endodontic treatment. The 0.7 mm flexible fiberoptic endoscope allows the endodontist to view canal morphology and biomechanical canal preparations, and helps to identify fractures, accessory canals, and remnant pulpal tissue.

Preliminary investigation of the histological effects of laser endodontic treatment on the periradicular tissues in dogs.

This study was conducted to determine the biological effects on the periradicular tissues of Nd:YAG laser endodontic treatment in dogs. Twelve vital teeth (24 roots) of two mongrel dogs were randomly selected to receive conventional or Nd:YAG laser endodontic treatment. Endodontic therapy was performed on the second, third, or fourth, right or left, mandibular premolars. The teeth were evaluated radiographically and histologically at 1, 15, and 30 days after endodontic treatment. The remaining teeth served as untreated controls. The results of this study revealed laser treatment causes cell necrosis in the periodontal ligament 1 day after treatment. Conventionally prepared teeth displayed no evidence of cell necrosis in the periodontal ligament. At 15 days posttreatment, both the laser and conventionally treated teeth showed increased size and numbers of osteocytes and osteoclasts in the periradicular bone. Additionally, laser-treated teeth showed signs of initial bone resorption. At 30 days posttreatment, conventionally treated teeth began to return to normal morphology. The laser-treated teeth exhibited ankylosis, cemental lysis, and major bone remodeling.

An endoscopic technique for endodontic surgery.

Modern endoscopy has been in existence for > 100 yr. As the desire for increased visualization in endodontic surgery continues, there is a constant search for better instruments and techniques to meet this demand. Endoscopy provides the surgeon with outstanding vision and ease of use. This study refines the endoscopic technique for endodontic surgery.

Effect of rotational speed on the breakage of nickel-titanium rotary files.

Nickel-titanium 0.04-tapered rotary files were evaluated for breakage at different rotational speeds in semicircular bovine bone simulated root canals of identical size and radius for each file size group tested. The bovine bone canals had a radius of curvature of 5 mm and a canal width equivalent to the D1 diameter of the file plus 0.04 mm. Profile instrument #3, #4, and #5 were tested at 150, 250, and 350 rpm. A contra-angle electric handpiece was mounted on an Instron machine that was set to deliver a constant downward speed of 5 mm/min. The electric handpiece and Instron machine were activated until the files broke. The amount of file tip penetration into the semicircular bovine bone canal was measured in degrees with a protractor from a radiographic image taken of the file inside the bone model. Greater degrees of tip penetration indicated greater resistance to breakage. Statistical analysis was done and the results indicated that there was a significant difference for all file sizes in the extent of file tip penetration before breakage. In the rotation range between 150 and 350 rpm the greatest extent of penetration occurred at 150 rpm. This study concluded that 0.04 taper nickel-titanium rotary file breakage is less likely to occur if the files are rotated at lower speeds.

In vitro evaluation of the XR-15 portable x-ray unit for forensic odontology.

The purpose of this research was to investigate if a portable, light-weight radiographic generator, Golden Engineering's XR-150, can be used in forensic odontology to aid identification. Dental periapical radiographs produced by the XR-150 were evaluated for diagnostic quality based on sharpness, detail, and whether the lamina dura, periodontal membrane space and bone trabeculae could be observed. Logistic regression was used to calibrate the evaluators for reliability and for comparison of impulse values within the different sites at p<0.01. Spearman's Correlation was used to test for significance between the four quadrants at p<0.01. The XR-150 produced statistically significant (p<0.01) diagnostic images between five and ten impulses in all locations tested: anterior maxilla, anterior mandible, posterior maxilla, and posterior mandible.

Understanding and evaluating the endodontic file.

One of the most significant advancements in the field of endodontics has been the change in the endodontic file. The new files have different metallurgy, taper, cutting efficiency, and rotary capabilities. This article reviews and updates the advancements in endodontic instrumentation.

Orascopic endodontics: changing the way we "think" about endodontics in the 21st century.

Orascopic endodontics has helped bring visualization to what has literally been a "blind" specialty. The ease of operation and better operating ergonomics of fiber optic instrumentation has allowed the endodontist to identify and treat endodontic etiology more efficiently. The metamorphosis of understanding endodontics from an in vivo perspective is changing the way we "think" about the practice of endodontics. Prior to intracanal visualization, the cognitive process of determining when the canal was ready for obturation was merely an educated guess based on years of in vitro instrumentation research and postoperative follow-up studies.

Orascopy: a vision for the new millennium, Part 2.

The advent of orascopy as a cutting edge technique has changed the way endodontists visualize as well as think about endodontics. As practitioners begin to see and understand endodontic etiology, it will enable oral physicians to provide treatment based on visual confirmation rather than radiographic estimates. In the future, conventional orascopic endodontics will be done very much like physicians provide treatment. It will be more qualitative rather than quantitative. Dentists will not need to make measurements of canals from radiographs; they will use orascopy to instrument, irrigate, and obturate while viewing the root canal system in real time. Surgical orascopic endodontics will continue to improve surgical treatment results because enhanced visualization has enabled endodontic surgeons to identify and treat endodontic etiology.

Limits on the high-energy gamma and neutrino fluxes from the SGR 1806-20 giant flare of 27 December 2004 with the AMANDA-II detector.

On 27 December 2004, a giant gamma flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV-1 m;{-2} s;{-1} for gamma=-1.47 (-2) in the high-energy neutrino flux.

Orascopic visualization technique for conventional and surgical endodontics.

AIM: To present a technique of integrating fibre optic orascope and rod-lens endoscope for visualization in conventional and surgical endodontic treatments. SUMMARY: Innovative advancements in fibre optic and rod-lens endoscope technology have allowed for the development and evolution of orascopic endodontics. The use of orascopy in conventional and surgical endodontic treatments has enabled the endodontist to become more discerning about the endodontic aetiology and the treatment procedures. Orascopy is a procedure that uses an orascope or a rod-lens endoscope for visualization in the oral cavity. An orascope is made up of fibre optics and an endoscope is made up of glass rods. Orascopic endodontics is the use of orascopy for visualization in conventional or surgical endodontic treatment. A 0.8 mm lens diameter, 0 degree, 10K fibre optic orascope and a 4 mm lens diameter, 30 degree, 4 cm rod-lens endoscope are used for visualization in conventional endodontics. The 2.7 mm lens diameter, 70 degree, 3 cm long rod-lens endoscope is used for visualization in surgical endodontics.