bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Resistance and Stress of Wrought‐Steel Wire Clasps
Authors: Vallittu Pekka K.
Published: March 2005

Purpose

The objective of this study was to determine the fatigue resistance of wrought‐steel wire clasps used for removable partial dentures.

Materials and Methods

Five wrought‐steel wires with cross‐sectional diameters of 1.2,1.1,1.0, 0.9, and 0.8 mm were tested using a deflection fatigue test with deflections of 0.4 to 0.7 mm. The force and stress required to cause deflection was determined, as well as the number of loading cycles required to cause fatigue fracture. The fracture surfaces of the wrought‐steel wire clasps were examined with a scanning electron microscope.

Results

The number of loading cycles required to cause fatigue fracture increased with reduced deflection of the wrought wire (p < .005). To obtain fatigue resistance for loading cycles of over 106, the stress in the wrought‐steel wire clasp should remain under 1.0 GPa.

Conclusions

These results suggest that to avoid fractures of wrought‐steel wire clasps caused by bending fatigue, the stress on the clasp during its deflection should be taken into account.
The Results of a Brief Survey of Complete Denture Prosthodontic Techniques in Predoctoral Programs in North American Dental Schools
Authors: Arbree Nancy S. , Fleck Sigmund , Askinas Samuel W.
Published: March 2005

A brief mail survey of North American dental schools was undertaken to ascertain the current techniques in complete denture prosthodontics regarding preliminary and final impressions, record bases, and denture teeth. Of the 64 schools surveyed, 54 responded (84%). Seventy‐four percent of the respondents used only irreversible hydrocolloid (alginate) for their preliminary impressions; 15% used only modeling plastic impression compound. Eighty‐one percent used only modeling plastic impression compound for border molding of the final impression tray; 7% used only polyether impression material. Forty‐eight percent used only polysulfide rubber (PR) impression material for their final impression material; 4% used only polyether impression material. Only 1 school still used shellac as one of its materials for record bases. Thirty‐five percent used only Triad; 35% used only acrylic resin; 24% used both of these materials. Thirteen percent of responding schools used only nonanatomic teeth. The majority (54%) used all three options (nonanatomic, semianatomic, and anatomic). Eleven percent used lingualized occlusion. As compared with a survey performed in 1985, the use of irreversible hydrocolloid as a preliminary impression material, the use of visible light‐cured resins for record bases, and the use of anatomic teeth have increased. The use of plastic impression compound for border molding and PR as the final impression material has largely remained the same.
Book Reviews
Authors: Truhlar Richard S.
Published: March 2005

Thomas G. Wilson, Jr. Quintessence Publishing Co, Chicago, Illinois
Evaluation of Stresses and Forces in Selected I‐Bars Using the Finite Element Method
Authors: Naik Preeti R. , Duncanson Manville G. , Mitchell Donald L. , Wiebelt Frank J. , Johnson Dean L. , Ghosh Joydeep
Published: March 2005

Purpose Three‐dimensional models of half‐round, tapered and full‐round, untapered I‐bar clasps of varying configurations and material properties were constructed. The purpose of this study was to examine the stresses and reaction forces produced within each model upon deflection to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm) at 1 mm from the tip using the finite element method.

Materials and Methods Three‐dimensional computer models of half‐round and full‐round clasps were constructed using solid eight‐node brick elements. The half‐round, tapered I‐bar clasp model was 2.4 and 1.4 mm in diameter at the base and tip, respectively. The full‐round, tapered I‐bar clasp model was 1 mm in diameter. Three design groups were created for each clasp form. Group A had 25% of the total length in the straight anchor end of the I‐bar clasp, B had 35%, and C had 50%. All models were 31 mm in length and had a radius of curvature of 5 mm. Different material properties were incorporated into the models. Each model was deflected at a point 1 mm from the tip to 0.01 in (0.254 mm), 0.02 in (0.508 mm), and 0.03 in (0.762 mm).

Results The stresses and forces produced as a result of the deflection applied to each clasp were viewed and displayed graphically. The maximum von Mises stresses in megapascals and the reaction force in newtons (N) were recorded. Stresses varied in each clasp in the range of 0 to 154.3 MPa for the half‐round, tapered I‐bar clasp models, and 0 to 100.9 MPa for the full‐round I‐bar clasp models at 0.01‐in deflection. Reaction force measured near the tip of the clasp models was between 1.60 N and 6.31 N for the half‐round, and between 0.22 N to 2.13 N for the full‐round I‐bar clasp models. For all clasps studied, as the deflection increased, the location of stress within each group remained the same regardless of the material properties; however, the stress and force values increased linearly.

Conclusions The location of maximum stress varied with the length of the anchor portion of the clasps studied. Maximum stresses were located on the flat side of the half‐round, tapered I‐bar clasp model.
The Fixed/Detachable Implant Provisional Prosthesis
Authors: Cibirka Roman M. , Linebaugh Michael L.
Published: March 2005

Interim modification and management of a complete denture following surgical uncovering of dental implants can be time‐intensive and may fail to provide adequate patient benefit until the definitive prosthesis can be completed. Inadequate interim management can result in functional and tissue difficulties. Modification of the conventional complete denture to a fixed/detachable provisional prosthesis in a one‐stage procedure provides the patient an opportunity to experience a fixed prosthesis. The incorporation of fixed, provisional cylinders to the existing denture base using autopolymerizing acrylic resin with a closed‐mouth technique is described. The peripheral regions are reduced and the distal extension shortened to resemble a fixed/detachable prosthesis. This conversion technique can provide patient satisfaction and comfort until delivery of the definitive prosthesis. Esthetic concerns, home care problems, or patient difficulties with the provisional prosthesis can be rectified in the final prosthesis.
The Management of Implant‐Retained Overdenture Treatment With Custom‐Made Metallic Attachment Housing
Authors: Cheng Ansgar C. , Wee Alvin G. , Maxymiw Walter , Morrison David
Published: March 2005

A technique using a custom‐made cast alloy attachment housing for an implant‐retained overdenture prosthesis is presented. Common problems encountered in implant‐tissue bar‐retained overdentures are discussed. Details of the modified laboratory procedure are described. This technique provides the clinician with an alternative for predictably treating patients with implant‐retained overdentures.
Palatogram Assessment of Maxillary Complete Dentures
Authors: Farley David W. , Jones John D. , Cronin Robert J.
Published: March 2005

Phonetics, esthetics, function, and comfort form the foundation of a successful dental prosthesis. A review of the mechanics of speech as well as common speech problems encountered with a removable maxillary prosthesis are presented. The use of a palatogram to aid the clinician in the assessment and resolution of speech problems associated with a maxillary denture is demonstrated.
CREST Syndrome: Clinical Manifestations and Dental Management
Authors: Chaffee Nancy R.
Published: March 2005

Scleroderma is a multisystem connective tissue disease of unknown etiology, which is characterized by inflammation, vascular, and fibrotic changes of the skin as well as various internal organs. This article will review the systemic form of scleroderma known as CREST syndrome, its clinical manifestations including the dentofacial complications, as well as provide information to assist the prosthodontist in managing the dental treatment for patients with this disease.
Predoctoral Fixed Prosthodontics Curriculum Survey
Authors: Petropoulos Vicki C. , Weintraub Annette , Weintraub Gerald S.
Published: March 2005

Purpose In 1996, a survey of American dental schools was conducted. The purpose of the survey was to determine the curricular structure, techniques taught, and materials used in predoctoral fixed prosthodontics courses.

Materials and Methods The survey was mailed to the course directors of predoctoral fixed prosthodontic programs at 53 American dental schools. Of these, 42 schools returned the completed survey, resulting in a response rate of 79%. The mean, median, and the range of responses were computed where applicable.

Results The results from this survey show that the mean student‐to‐faculty ratio in the preclinical course was 11:1, with a median of 10:1 and a range of 5:1 to 25:1. The mean number of laboratory clock hours was 164, with a median of 148 and a range of 81 to 288. The mean number of lecture hours reported was 42, with a median of 35 and a range of 20 to 80. Fifty‐five percent of the schools used the Hanau semiadjustable articulator. The most commonly used provisional technique was the thermoplastic custom external surface form (44%). The finish line of choice for the full metal restoration was the chamfer placed circumferentially (74%). The finish line of choice for the porcelain‐fused‐to‐metal restoration was the shoulder placed facially and the chamfer placed lingually (38%).

Conclusions Predoctoral fixed prosthodontics education and technical experience varies from school to school, yet a large percentage of schools agree on certain topics.
Working Times and Dimensional Accuracy of the One‐Step Putty/Wash Impression Technique
Authors: Richards Mark W. , Zeiaei Saeid , Bagby Michael D. , Okubo Scott , Soltani Jamshid
Published: March 2005

Purpose Using the one‐step polyvinyl siloxane impression technique, this study compared the effect of putty material working time on the dimensional accuracy of recovered improved stone casts.

Materials and Methods An acrylic resin master cast was fabricated with embedded reference points to enable both horizontal and vertical measurements. Four commercially available polyvinyl siloxane impression putties with light body washes were evaluated: 1) Extrude (Kerr), 2) Cutter (Coltere), 3) Express (3M), and 4) Reprosil (Caulk). Each putty was mixed by hand for 30 seconds, placed in a plastic stock tray, and seated on the master cast at 0, 30, 60, 90, and 120 seconds after mixing (N = 100, n = 5). The impressions were poured in improved stone, and vertical and horizontal measurements were made to 0.001 mm between reference points on recovered casts using an optical traveling microscope. ANOVA (p .05) was used to compare vertical and horizontal measurements to master cast dimensions.

Results No statistically significant difference was found among casts for all materials and time periods tested. When horizontal measurement ranges were evaluated, Extrude casts exhibited the widest range of measurement, especially when the trays were seated at 90 and 120 seconds. When vertical measurement ranges were evaluated, Express casts at 120 seconds exhibited the widest range.

Conclusions A high range of variability in vertical and horizontal dimensions occurred at the later time periods, especially for Extrude and Express casts. As a result of rapid polymerization and poor flow properties of putty materials, the impression tray should be seated within 60 seconds after putty mixing to reduce dimensional variability of recovered casts.
Template for Surgical Crown Lengthening: Fabrication Technique
Authors: Walker Mary , Hansen Paul
Published: March 2005

This article describes a technique for the easy fabrication of a template to facilitate surgical lengthening of the clinical crown to enhance esthetics and/or increase retention of a fixed prosthesis. The use of this surgical guide should result in more predictable clinical results.
Centric Relation Registration Using an Anterior Deprogrammer in Dentate Patients
Authors: Hunter Benjamin D. , Toth Richard W.
Published: March 2005

A technique is described for registering centric relation in dentate patients using an anterior deprogrammer to prevent muscle splinting. Properly executed, the patient is able to close into centric relation unassisted, eliminating the possibility of operator‐induced error associated with commonly accepted manipulative techniques. Verification is possible visually when articulating casts by confirming the precise alignment of the mandibular incisors with occlusal markings on the deprogrammer attached to the maxillary cast.
A Survey of Private Prosthodontic Practice
Authors: Dickey Keith Winfield
Published: March 2005

The data from a survey of private prosthodontic practitioners are reported in this article. The author provides a brief look at employment status, number of employees, time spent in the office, number of patient visits per week, gross billings, net income, and practice expenses of prosthodontic practices. In addition, the author has developed a profile for a median prosthodontic practice and practitioner.
Current Methods of Finish‐Line Exposure by Practicing Prosthodontists
Authors: Hansen Paul A. , Tira Daniel E. , Barlow Jeff
Published: March 2005

Purpose

The purpose of this study was to survey members of The American College of Prosthodontists to evaluate current methods of finish‐line exposure. In addition, frequency of use of epinephrine compounds and observed side effects were assessed.

Materials and Methods

A questionnaire was mailed to the 2,436 members of The American College of Prosthodontists. Group differences were evaluated using x2 analysis.

Results

Completed questionnaires were returned by 1,246 prosthodontists, which is a return rate of 51%. Ninety‐eight percent of respondent prosthodontists use retraction cord, and 48% use a double‐cord technique. Plain cord is the most commonly used cord (44%), followed by aluminum chloride‐impregnated cord (18%), and epinephrine‐impregnated cord (14%). Nine hundred one respondents (81%) soak the cord before placing it in the gingival sulcus. The most common medicament for soaking the cords is buffered aluminum chloride (55%). Side effects to epinephrine were reported by 387 respondents (33%), with the most common side effect reported being increased pulse rate, followed by anxiety. Approximately one quarter (24%) of the prosthodontists surveyed had observed side effects to chemical agents other than epinephrine.

Conclusions

Prosthodontists throughout the country use many different techniques and agents to expose finish lines. No statistically significant differences (p > .05) were found between year of specialty training completion groups with respect to retraction cord use. Copper bands are used significantly more frequently (p < .05) in the northwest region of the United States than elsewhere.
Infrared Gold Alloy Brazing on Titanium and Ti‐6Al‐4V Alloy Surfaces and its Application to Removable Prosthodontics
Authors: Wakabayashi Noriyuki , Ai Minoru , Iijima Kazunori , Takada Yukyo , Okuno Osamu
Published: March 2005

Purpose

This study investigated the area size of the flow of a gold braze alloy on commercially pure titanium and Ti‐6AI‐4V alloy plates, and elemental composition at the interface was determined. In the second part of this study, the tensile strengths of titanium plates brazed using a gold alloy were investigated.

Materials and Methods

Chips of Type IV gold alloy and silver braze alloys were melted onto commercially pure titanium and Ti‐6AI‐4V surfaces in a dental infrared radiation unit. Flow area of each braze alloy was measured using a digital image analyzer. Tensile specimens (n = 5) were also prepared by infrared brazing using the braze alloys. Five specimens for each combination of the two titanium plates and the two braze alloys were subjected to tensile loading using a Universal testing machine. Electronprobe microanalysis of x‐rays at cross‐section of the brazed joints to determine elemental composition across the interface, as well as scanning electron microscopic observation at the fracture surfaces, were also conducted.

Results

The braze alloys flowed well and spread over the Ti and Ti‐6AI‐4V plates. Braze alloy type significantly influenced flow, and the gold alloy flowed less on the titanium materials. The mean tensile strengths of Ti and Ti‐6AI‐4V plates brazed using the gold braze alloy were 219 MPa and 417 MPa, respectively. The fracture surfaces of Ti‐6AI‐4V specimens with the gold braze alloy exhibited typical ductile behavior. Ti with the same braze alloy showed brittle surfaces. A greater concentration of Cu was found at the Ti with gold braze interface.

Conclusion

The flow and the tensile strength of the gold alloy coating on titanium surface by means of an infrared brazing is adequate for dental use.
Dental Burs—What Bur for Which Application? A Survey of Dental Schools
Authors: Siegel Sharon Crane , von Fraunhofer Joseph Anthony
Published: March 2005

Purpose

The purpose of this study was to survey North American dental schools regarding recommendations for rotary instrumentation for fixed prosthodontic and operative procedures at the predoctoral and postgraduate level.

Materials and Methods

A 25‐question survey was sent to 64 North American dental schools, of which 15 questions specifically related to rotary instrument recommendations. One questionnaire was addressed to the individual at each school having administrative responsibility for teaching tooth preparation techniques. A high response rate was assured by follow‐up telephone calls and faxes. The distributions of bur recommendations for both predoctoral and advanced prosthodontic programs were analyzed by chi‐squared tests at an a priori α= 0.05.

Results

Completed surveys were received from 58 of 64 dental schools, a response rate >90%. Medium grit burs predominate in predoctoral education for gross tooth reduction for fixed prosthodontics, whereas coarse grit burs predominate at the graduate level (p < .05). The use of the diamond bur alone predominates for axial wall refinement, whereas the use of carbide burs or carbide burs in combination with diamond burs prevails for marginal refinement (p < .05). In predoctoral operative dentistry, recommendations for cavity outline form were similar at all dental schools (p > .05) and were principally tungsten carbide (WC) burs. Carbide burs are the instrument of choice for internal walls, but the WC bur alone or in combination with diamond burs is preferred for refining composite margins (p < .05).

Conclusions

There is a broad consensus within North American dental schools on rotary instrumentation used by dental students. There is a greater use of coarser grit burs for gross tooth reduction in fixed prosthodontics at the postgraduate than predoctoral level.
A Technique to Create Appropriate Abutment Tooth Contours for Removable Partial Dentures
Authors: Alfonso Carlos , Toothaker R. W. , Wright Robert F. , White G. Shelby
Published: March 2005

A technique is presented for using light‐cured composite resin to create desirable contours on abutment teeth for the retention and support of removable partial dentures. The desired tooth shape is created on a diagnostic cast, captured in a clear temporary splint material, and formed in resin on the abutment teeth with the splint acting as a matrix.
Results after replantation of avulsed permanent teeth. I. Endodontic considerations
Authors: Pohl Yango , Filippi Andreas , Kirschner Horst
Published: March 2005

Abstract –  Following avulsion and replantation, teeth are at risk for infection and infection related resorption (IRR). Severe discolorations of tooth crowns and cervical root fractures are common. This study presents data on endodontic related complications of avulsed teeth replanted following an extraoral endodontic treatment. Periodontal aspects will be discussed in the second part of the present publication. Twenty‐eight permanent teeth in 24 patients aged seven to 17 years were replanted after avulsion. All teeth could be evaluated. In all teeth extraoral endodontic treatment by retrograde insertion of ceramic or titanium posts was performed. Mean observation period was 31.2 months (median: 24.1 months). Nine teeth healed with a functional peridontal ligament (PDL) (functional healing, FH), 19 teeth exhibited replacement resorption (RR), which was succeeded by IRR in three teeth after observation periods of more than 14 months. Diagnosis was set to tunneling resorption (one case) and to cervical resorption preceded by complete RR (two cases). No early IRR was observed. All six teeth rescued in physiologic conditions (cell culture medium of tooth rescue box) exhibited FH. Discolorations of tooth crowns or other complications (cervical root fractures, fractures of posts) were not observed. No differences in the healing results of immature and mature teeth were observed which is in contrast to previous studies. This finding is explained with the different endodontic treatment protocols. Extraoral endodontic treatment by retrograde insertion of posts prevents early IRR and minimizes the overall incidence of IRR. The method does not negatively influence periodontal healing. As there are further advantages (no discoloration, no root fractures, patient not involved, less radiographs, less time consumption, less costs) the method is recommended in isolated teeth before replantation. Especially immature teeth profit from the prevention of complications.
Mathematical Model for Pressure Losses in the Hemodialysis Graft Vascular Circuit
Authors: Jones Steven A. , Jin Song , Kantak Ameya , Bell David A. , Paulson William D.
Published: March 2005

Stenosis-induced thrombosis and abandonment of the hemodialysis synthetic graft is an important cause of morbidity and mortality. The graft vascular circuit is a unique low-resistance shunt that has not yet been systematically evaluated. In this study, we developed a mathematical model of this circuit. Pressure losses ΔPs were measured in an in vitro experimental apparatus and compared with losses predicted by equations from the engineering literature. We considered the inflow artery, arterial and venous anastomoses, graft, stenosis, and outflow vein. We found significant differences between equations and experimental results, and attributed these differences to the transitional nature of the flow. Adjustment of the equations led to good agreement with experimental data. The resulting mathematical model predicts relations between stenosis, blood flow, intragraft pressure, and important clinical variables such as mean arterial blood pressure and hematocrit. Application of the model should improve understanding of the hemodynamics of the stenotic graft vascular circuit.
Simultaneous Measurement of Three-Dimensional Joint Kinematics and Ligament Strains With Optical Methods
Authors: Lujan Trevor J. , Lake Spencer P. , Plaizier Timothy A. , Ellis Benjamin J. , Weiss Jeffrey A.
Published: March 2005

The objective of this study was to assess the precision and accuracy of a nonproprietary, optical three-dimensional (3D) motion analysis system for the simultaneous measurement of soft tissue strains and joint kinematics. The system consisted of two high-resolution digital cameras and software for calculating the 3D coordinates of contrast markers. System precision was assessed by examining the variation in the coordinates of static markers over time. Three-dimensional strain measurement accuracy was assessed by moving contrast markers fixed distances in the field of view and calculating the error in predicted strain. Three-dimensional accuracy for kinematic measurements was assessed by simulating the measurements that are required for recording knee kinematics. The field of view (190 mm) was chosen to allow simultaneous recording of markers for soft tissue strain measurement and knee joint kinematics. Average system precision was between ±0.004 mm and ±0.035 mm, depending on marker size and camera angle. Absolute error in strain measurement varied from a minimum of ±0.025% to a maximum of ±0.142%, depending on the angle between cameras and the direction of strain with respect to the camera axes. Kinematic accuracy for translations was between ±0.008 mm and ±0.034 mm, while rotational accuracy was ±0.082 deg to ±0.160 deg. These results demonstrate that simultaneous optical measurement of 3D soft tissue strain and 3D joint kinematics can be performed while achieving excellent accuracy for both sets of measurements.
Two freshman courses which introduce digital electronics, programming, computers, and interfacing
Authors: Seligmann P. , Spencer C. D.
Published: March 2005

This article describes two one-credit freshman courses intended to familiarize students with the laboratory use of computers. The courses provide an introduction to programming in a high level language (BASIC) and in assembly language and to the design and construction of simple digital circuits. A final project requires students to interface an electronic thermometer to an S-100 Bus machine.
The conical bore in musical acoustics
Authors: Ayers R. Dean , Eliason Lowell J. , Mahgerefteh Daniel
Published: March 2005

A survey of descriptive textbooks on musical acoustics shows a need for a legitimate, convincing explanation for the seemingly paradoxical behavior of the conical bore. We examine the differential equations and their solutions for spherically symmetric waves in three dimensions, settling on acoustic pressure as the variable of interest because it behaves more simply than particle velocity or displacement. Next we solve the boundary-value problem for all combinations of open and closed ends on truncated cones. The natural frequencies so obtained are then justified with plots of the pressure standing waves; it is at this point that we find a physically correct explanation that can be shared with students in a descriptive acoustics course. This pictorial approach is also used to explain the shapes of the input impedance curves for a straight pipe and a frustum. We conclude with a careful analysis of the successive distortions to which a pressure pulse is subjected as it bounces back and forth inside a frustum.
Galloping waves and their relativistic properties
Authors: Harter William G. , Evans John , Vega Roberto , Wilson Sanford
Published: March 2005

The superposition and resulting interference of two oppositely moving waves generally yield a wave having nonuniform motion. Space-time plots of constant-phase points provide a convenient way to exhibit a range of different types of wave phenomena including the relationship between moving and standing waves. Doppler-shifted versions of the same plots provide a novel approach to Minkowski graphs and Lorentz transformations. Relativistic properties of interfering electromagnetic plane waves are discussed.
On reflection and refraction of x rays by ideal mirrors and thin films
Authors: Lee Ping
Published: March 2005

The problem of reflection and refraction of x rays at ideal plane parallel interfaces has been examined based upon the Fresnel equations derived from the classical electromagnetic theory and it has been shown to be identical to the inhomogeneous wave model of Mahan. Furthermore, it is also shown that the reflection coefficient for a thin film in the limit of a monolayer of atoms, large angle of incidence θ, and sin θ/λ≪10 nm−1 is identical to the crystal diffraction model.
On relativistic gravitation
Authors: Bedford D. , Krumm P.
Published: March 2005

The existence of a gravitational analog of the magnetic field is demonstrated very easily by considering a special case.
Temperature of incandescent lamps
Authors: Zanetti Vittorio
Published: March 2005

A method for determining filament temperatures of commercially available incandescent lamps has been presented. The light emitted by a filament at two well-defined wavelengths has been measured by means of two silicon solar cells with interference filters. Since the ratio r of the two signals so determined is a function of the filament temperature, an r against T calibration curve is needed, in order to obtain the filament temperature itself. This calibration curve is determined by means of the well-known dependence of tungsten resistivity on absolute temperature. Considerations about the color index of a star can be raised.
The depolarization field inside a homogeneous dielectric: A new approach
Authors: Zapolsky Harold S.
Published: March 2005

A simple argument is presented to make plausible the theorem that a homogeneous dielectric placed in a uniform external field is uniformly polarized only if its shape is ellipsoidal. Expressions for the depolarization factors are displayed in a form which makes immediately apparent the well-known sum rule. An additional symmetry relation between the depolarization factors is used to write integral expressions for them. It is shown that these factors reduce to the standard form. Neither Dirichlet’s integral representation nor ellipsoidal coordinates are used in this derivation.
The Hamiltonian formulation of optics
Authors: Sekiguchi Tetsundo , Wolf Kurt Bernardo
Published: March 2005

Snell’s law of refraction is a conservation law of optical momentum. In infinitesimal form, it leads directly to the Hamilton equations for geometrical optics. The latter guarantee that the transformation of optical phase space produced by propagation through a medium where the index of refraction is continuously differentiable, is canonical. Discontinuous-index systems such as refracting surfaces must be treated through a complementary description to show that they are also canonical. They have recently been shown to factorize into two ‘‘root’’ transformations, each depending on the properties of a single medium, and each canonical. This factorization is applicable to reflection off curved mirrors as well.
Relativistic telemetry
Authors: Peres Asher
Published: March 2005

Many relativistic formulas can be derived without explicitly using Lorentz transformations but, instead, directly from Einstein’s postulate: ‘‘All physical laws are the same for all inertial observers.’’ These formulas include time dilation, addition of velocities, the Doppler effect, and optical aberration. From the visual picture seen by one observer, one can deduce the picture seen at the same space-time point by any other observer, without knowing anything about the speed or the three-dimensional shape of the observed object. In particular, the apparent visual shape of a moving object is not contracted, but rotated.
Franck–Hertz experiment with higher excitation level measurements
Authors: Liu F. H.
Published: March 2005

The measurement of the higher levels of 63P2 and 61P1 of the mercury atom in the Franck–Hertz experiment has been introduced into the junior and senior laboratory course by using a homemade tetrode Franck–Hertz tube. The main structure of the tube is described. The optimum operating conditions are in the temperature range between 130 and 150 °C and the collector currents are of the order of 10−9 A. The additional observations of the famous Franck–Hertz experiment in the laboratory course will give the students more familiarity with the quantum behavior of atoms.
Uniformly accelerated reference frames in special relativity
Authors: Desloge Edward A. , Philpott R. J.
Published: March 2005

A uniformly accelerated reference frame S is defined as a set of observers who remain at rest with respect to a given observer A who is accelerating at a constant rate with respect to the instantaneously comoving inertial frames. The one-dimensional uniformly accelerated reference frame S is considered. The world lines of A and the other observers making up S are determined. Coordinates useful for describing events in S are carefully defined and the transformation equations between different sets of them are derived. The variation with position in S of the speed and frequency of light waves is determined. The motion of a free-particle in S is determined. Various phenomena in S, ordinarily associated with general relativity, are considered, in particular the asymmetric aging of twins at rest at different positions and the existence of horizons.
Carnot’s function: Origins of the thermodynamic concept of temperature
Authors: Cropper William H.
Published: March 2005

This paper traces an important chapter in the evolution of the temperature concept in classical thermodynamics. The centerpiece in the story is the temperature function discovered by Carnot, and gradually developed over a period of 30 yr by Clapeyron, Holtzmann, Helmholtz, Joule, Rankine, Thomson (Kelvin), and Clausius. In Thomson’s final resolution of the problem, Carnot’s function simply determined the thermodynamic temperature scale.
Comments on the horizontal deflection of a falling object
Authors: Belorizky Elie , Sivardière Jean
Published: March 2005

The southward deflection of a falling object is derived from an exact calculation by Potgieter in the model of a perfectly spherical Earth. The result is physically interpreted in a reference frame fixed to the Earth. The classical expression given by Sommerfeld is corrected.
Effect of nonsteroidal anti-inflammatory drugs with varying extent of COX-2–COX-1 selectivity on urinary sodium and potassium excretion in the rat
Authors: Harirforoosh Sam , Jamali Fakhreddin
Published: March 2005

Nonsteroidal anti-inflammatory drugs (NSAIDs) have different selectivity to inhibit cyclooxygenase-1 (COX-1) and COX-2. Treatment with NSAIDs has been associated with kidney side effects. We compared the effect of a selected group of NSAIDs with different COX-2–COX-1 selectivities on urinary sodium and potassium excretion in rats. Each treatment with rofecoxib, celecoxib, meloxicam, diclofenac, and flurbiprofen (30, 120, 9, 30, and 125 mg/kg, respectively) and placebo was administered orally once daily for 4 days. Urine was collected 0–8 h after each dose. Urinary sodium and potassium excretion and urine flow rate were compared with placebo. As compared with placebo, rofecoxib, celecoxib, diclofenac, and flurbiprofen significantly reduced excretion rate of sodium (rofecoxib, 0.28 ± 0.02 vs. 0.41 ± 0.03; celecoxib, 0.23 ± 0.03 vs. 0.48 ± 0.04; diclofenac, 0.09 ± 0.02 vs. 0.46 ± 0.03; and flurbiprofen, 0.11 ± 0.02 vs. 0.47 ± 0.02 µmol/(min × 100 g)) and potassium (rofecoxib, 0.55 ± 0.04 vs. 0.68 ± 0.04; celecoxib, 0.50 ± 0.06 vs. 0.72 ± 0.06; diclofenac, 0.26 ± 0.05 vs. 0.67 ± 0.04; and flurbiprofen, 0.35 ± 0.05 vs. 0.62 ± 0.03 µmol/ (min × 100 g)). Rofecoxib and flurbiprofen significantly reduced urine flow rate. Meloxicam had no significant effect on either sodium and potassium excretion or on the urine flow rate. At the examined dosage level, no relationship was found between reported COX-2–COX-1 selectivity and urinary electrolytes excretion.Key words: COX-1, COX-2, kidney, NSAIDs, urinary sodium excretion.
Congestive heart failure complicating non-ST segment elevation acute coronary syndrome: incidence, predictors, and clinical outcomes
Authors: Mehta Shamir R , Eikelboom John W , Demers Catherine , Maggioni Aldo P , Commerford Patrick J , Yusuf Salim
Published: March 2005

There are limited data regarding the incidence and clinical significance of congestive heart failure (CHF) in patients with non-ST segment elevation acute coronary syndromes (ACS). The objectives of this study were to examine the incidence, predictors, and clinical outcomes in patients with ACS without ST elevation who develop CHF. We studied patients with unstable angina or non-ST segment elevation myocardial infarction (NSTEMI) randomized to hirudin or unfractionated heparin in the Organisation to Assess Strategies for Ischemic Syndromes (OASIS-2) trial. The diagnosis of CHF was based on a combination of clinical and radiographic features. Patients were followed for 6 months. Of 10 141 randomized patients, 501 (4.9%) developed CHF within the first week and 643 (6.3%) during 6 months of followup. Independent predictors for the development of CHF were older age, female sex, diabetes, prior MI, prior CHF, and NSTEMI at presentation. Compared with patients who did not develop CHF, patients who developed CHF were at increased risk of death (odds ratio (OR) 3.4, 95% CI 2.7–4.3), new MI (OR 2.8, 95% CI 2.2–3.6), and the need for intra-aortic balloon pump insertion (OR 5.4, 95% CI 3.5–8.4) at 7 days and 6 months. There was no increase in use of cardiac catheterization (OR 0.8, 95% CI 0.7–1.0) or revascularization (OR 0.9, 95% CI 0.7–1.1) in patients who developed CHF. CHF is a common complication in patients presenting with non-ST segment elevation ACS and is strongly associated with adverse clinical outcomes including new MI and death. Despite this worse prognosis, patients with ACS developing CHF are less likely to be referred for invasive management.Key words: unstable angina, acute coronary syndrome, congestive heart failure, prognosis.
The dual integral equation method in hydromechanical systems
Authors: Kavallaris N. I. , Zisis V.
Published: March 2005

Some hydromechanical systems are investigated by applying the dual
integral equation method. In developing this method we suggest
from elementary appropriate solutions of Laplace′s equation, in
the domain under consideration, the introduction of a potential
function which provides useful combinations in cylindrical and
spherical coordinates systems. Since the mixed boundary conditions
and the form of the potential function are quite
general, we obtain integral equations with mth‐order Hankel kernels. We then discuss a kind of approximate practicable
solutions. We note also that the method has important applications
in situations which arise in the determination of the temperature
distribution in steady‐state heat‐conduction problems.
Time Rate of Blood Pressure Variation Is Associated With Increased Common Carotid Artery Intima-Media Thickness
Authors: Zakopoulos Nikos A. , Tsivgoulis Georgios , Barlas Gerassimos , Papamichael Christos , Spengos Konstantinos , Manios Efstathios , Ikonomidis Ignatios , Kotsis Vassilios , Spiliopoulou Ioanna , Vemmos Konstantinos , Mavrikakis Myron , Moulopoulos Spyridon D.
Published: March 2005

The extent of target-organ damage has been positively associated with the magnitude of blood pressure (BP) variability in essential hypertension. However, the clinical implications of the rate of BP changes have never been investigated. We evaluated the association between the rate of systolic BP (SBP) variation derived from ambulatory BP monitoring (ABPM) data analysis and the extent of common carotid artery (CCA) intima-media thickness (IMT) in normotensive (n=280) and in uncomplicated hypertensive subjects (n=234). The 24-hour rate of SBP variation was significantly (
P
<0.001) higher in hypertensive (0.608 mm Hg/min; 95% confidence interval [CI], 0.595 to 0.622) than in normotensive individuals (0.567 mm Hg/min; 95% CI, 0.555 to 0.578), even after adjusting for baseline characteristics, day–night BP changes, 24-hour heart rate (HR), SBP, and HR variability. In the entire group of patients, multiple linear regression models revealed independent determinants of CCA-IMT in the following rank order: age (
P
<0.001), 24-hour rate of SBP variation (
P
<0.001), male gender (
P
=0.004), cholesterol (
P
=0.009), and smoking (
P
=0.014). A 0.1 mm Hg/min increase in the 24-hour rate of SBP variation was associated to an increment of 0.029 mm (95% CI, 0.018 to 0.040) in CCA-IMT independent of BP and HR levels, BP and HR variability, and dipping status. The rate of SBP variation during the morning BP surge correlated independently (
P
<0.001) to larger CCA-IMT values after adjustment for baseline characteristics and other ABPM parameters. Thus, the rate of BP fluctuations is greater in hypertensive patients and correlates to increased CCA-IMT. This finding indicates that steeper BP variations may produce a greater stress on the vessel wall and consequently result in medial hypertrophy of the large arteries.
Angiotensin II-Dependent Chronic Hypertension and Cardiac Hypertrophy Are Unaffected by gp91phox-Containing NADPH Oxidase
Authors: Touyz Rhian M. , Mercure Chantel , He Ying , Javeshghani Danesh , Yao Guoying , Callera Glaucia E. , Yogi Alvaro , Lochard Nadheige , Reudelhuber Timothy L.
Published: March 2005

The gp91phox-containing NADPH oxidase is the major source of reactive oxygen species (ROS) in the cardiovascular system and inactivation of gp91phox has been reported to blunt hypertension and cardiac hypertrophy seen in angiotensin (Ang) II-infused animals. In the current study, we sought to determine the role of gp91phox-derived ROS on cardiovascular outcomes of chronic exposure to Ang II. The gp91phox-deficient mice were crossed with transgenic mice expressing active human renin in the liver (TTRhRen). TTRhRen mice exhibit chronic Ang II–dependent hypertension and frank cardiac hypertrophy by age 10 to 12 weeks. Four genotypes of mice were generated: control, TTRhRen trangenics (TTRhRen), gp91phox-deficient (gp91
−
), and TTRhRen transgenic gp91phox-deficient (TTRhRen/gp91
−
). Eight to 10 mice/group were studied. ROS levels were significantly reduced (
P
<0.05) in the heart and aorta of TTRhRen/gp91
−
and gp91
−
mice compared with control counterparts, and this was associated with reduced cardiac, aortic, and renal NADPH oxidase activity (
P
<0.05). Systolic blood pressure (SBP), cardiac mass, and cardiac fibrosis were increased in TTRhRen versus controls. In contrast to its action on ROS generation, gp91phox inactivation had no effect on development of hypertension or cardiac hypertrophy in TTRhRen mice, although interstitial fibrosis was reduced. Cardiac and renal expression of gp91phox homologues, Nox1 and Nox4, was not different between groups. Thus, although eliminating gp91phox-associated ROS production may be important in cardiovascular consequences in acute insult models, it does not prevent the development of hypertension and cardiac hypertrophy in a model in which the endogenous renin-angiotensin system is chronically upregulated.
Comparing OpenMP, HPF, AND MPI Programming: A Study Case
Authors: Berthou Jean-Yves , Fayolle Eric
Published: March 2005

This paper presents a comparison of three programming models—OpenMP, HPF, and MPI—applied to a diphasic compressible fluid mechanics code. The parallelization analysis is conducted, and the authors also present the experimental results obtained on various platforms: a Compaq Proliant 6000 (4 processors), a Cray T3E-750 (300 processors), an HP Class V (16 processors), a SGI Origin 2000 (32 processors), a cluster of PCs, and a COMPAQ SC 232 (232 processors). These experimental results will be discussed according to the following criteria: efficiency, scalability, maintainability, developing costs, and portability. As a conclusion, the authors present the parallelization strategy recommended for codes comparable to ECOSS.
Parallel Particle Simulations of Thin-Film Deposition
Authors: McCoy R. Alan , Deng Yuefan
Published: March 2005

Thin-film growth by sputter deposition is a manufacturing process that is well suited for study by particle simulation methods. The authors report on the development of a high performance, parallel, molecular-dynamics software package that simulates atomic metal systems under sputter deposition conditions. The package combines advanced techniques for parallel molecular dynamics with specialized schemes for the simulation of sputtered atoms impinging on thin films and substrates. The features of the package include asynchronous message passing, dynamic load balancing, mechanisms for data caching, and efficient memory management. For classical, semiempirical force calculations, the authors employ a modified version of the embedded-atom method with improved efficiency. Enhancements for the simulation of sputter deposition include an adjustable temperature control algorithm, the detection and ray tracing of emitted particles, and a Langevin localization procedure that restricts the dynamics computations to regions undergoing kinetic energy transfer. The authors describe in detail the features of the package, discuss its performance behavior, and also present some results from sputter deposition simulations.
A normalization strategy applied to HiCEP (an AFLP-based expression profiling) analysis: Toward the strict alignment of valid fragments across electrophoretic patterns
Authors: Kadota Koji , Fukumura Ryutaro , Rodrigue Joseph J , Araki Ryoko , Abe Masumi
Published: March 2005

Background

Gene expression analysis based on comparison of electrophoretic patterns is strongly dependent on the accuracy of DNA fragment sizing. The current normalization strategy based on molecular weight markers has limited accuracy because marker peaks are often masked by intense peaks nearby. Cumulative errors in fragment lengths cause problems in the alignment of same-length fragments across different electropherograms, especially for small fragments (< 100 bp). For accurate comparison of electrophoretic patterns, further inspection and normalization of electrophoretic data after fragment sizing by conventional strategies is needed.

Results

Here we describe a method for the normalization of a set of time-course electrophoretic data to be compared. The method uses Gaussian curves fitted to the complex peak mixtures in each electropherogram. It searches for target ranges for which patterns are dissimilar to the other patterns (called "dissimilar ranges") and for references (a kind of mean or typical pattern) in the set of resultant approximate patterns. It then constructs the optimal normalized pattern whose correlation coefficient against the reference in the range achieves the highest value among various combinations of candidates. We applied the procedure to time-course electrophoretic data produced by HiCEP, an AFLP-based expression profiling method which can detect a slight expression change in DNA fragments. We obtained dissimilar ranges whose electrophoretic patterns were obviously different from the reference and as expected, most of the fragments in the detected ranges were short (< 100 bp). The normalized electrophoretic patterns also agreed well with reference patterns.

Conclusion

The normalization strategy presented here demonstrates the importance of pre-processing before electrophoretic signal comparison, and we anticipate its usefulness especially for temporal expression analysis by the electrophoretic method.