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This article reviews medical-legal issues with regard to minors as they apply to the practice of emergency medicine. The topics of consent to treatment, refusal of care, child abuse, and medical malpractice are addressed. A working knowledge of these areas helps the emergency physician to avoid confusion, avoid delays in management, and maintain the safety of children.

Publisher Summary This chapter discusses quantum molecular dynamics (QMD) studies of the structure and dynamics of metal clusters. What is present in the chapter focuses on metal clusters with Al chosen as a paradigm. The structures of the clusters will play an important role in the assembly process and influence the properties of the final material. The chapter discusses the structures of larger Al clusters, looking at the icosahedral to fee phase transition via the first-principles Car-Parrinello (quantum molecular dynamics) approach. The results of such calculations can be used for the development of empirical potentials that would be suitable for classical molecular dynamics simulations of much larger clusters, cluster fusion, and the assembly of cluster materials. The chapter describes Car-Parrinello calculations that are focused on (1) investigating the transition between icosahedral and bulk (fee) cluster structures in Al, as a function of cluster size, and (2) on developing a database of first-principles results for determining an embedded atom potential for clusters.

Recent quantum molecular dynamics studies of Al and carbon clusters are described. For Al, we focused on the 13- and 55-atom clusters, which can assume perfect icosahedral and cubic structures. However, the distortions from these ideal structures are substantial. For the 55-atom cluster, several inequivalent but nearly energetically degenerate structures are found, due to the short range of the screened interatomic interactions. For solid C60, it is found that the soccerball structure is well-preserved in the solid. The intermolecular interactions are so weak that the individual C60 can rotate at relatively low temperatures. At high temperatures vibrations cause large distortions, but the cage structure is still preserved. The C60 isomer containing two pairs of adjacent five-fold rings has a binding energy only 1.6 eV smaller than that of perfect C60, but the transformation between these two structures is hindered by a 5.5 eV barrier. It thus requires high temperatures and long annealing times. High temperatures are also needed for the transformation of the lowest energy C20 isomer, a dodecahedron, to a corannulene structure, which can be thought of as a fragment of C60. The corannulene structure is a natural precursor for the formation of C60. These results are consistent with the experimental findings that high temperatures are necessary for the formation of substantial quantities of C60. A formulation and the first applications of a new, real space quantum molecular dynamics method, particularly suitable for cluster calculations, are also described.

Although the frequencies of the pulsating white dwarfs are extremely stable, the evolutionary cooling of these geometrically constrained objects should lead to an observable period change over a sufficiently long time base. Direct measurement of a period change rate for the cooler white dwarfs should provide fundamental data on the core composition of these stellar remnants, and hence their cooling time scales. Progress on attempts to measure the period change rates of two white dwarfs is reported.

The MOA Project is a collaboration of Japanese and New Zealand (NZ) astronomers and physicists undertaking a survey of stellar variability in the direction of the Galactic bulge and Magellanic Clouds. The primary motivation of the project is detection and monitoring of gravitational microlensing events although a large amount of data is also collected on stellar variability. Surveying the number of stars required to detect gravitational microlensing events is an operation of some magnitude and requires sophisticated data processing software.

A large database of CCD photometry for 1.4 million stars towards both the LMC and the SMC, which has been established by the MOA project, is a useful resource to study variable stars. In our preliminary study, variables identified as β Lyrae type stars and Herbig Ae/Be stars have been found amongst blue stars.

The energetics and structures of metallic clusters containing up to 55 atoms are studied by the Car-Parrinello (quantum-molecular dynamics) method with Al chosen as a paradigm. It is found that the structural energy differences between small cluster (icosahedral) and bulk (fee) structures are surprisingly small, indicating that the icosahedron-fee structural transition can occur very early in Al clusters. Simulated annealing studies for 13- and 55-atom clusters, where both perfectly symmetric icosahedral and cuboctahedral (fee) structures exist, show that the distortions from the ideal structures are substantial. For the 55-atom cluster several inequivalent but energetically nearly degenerate structures are found, which is likely to lead to floppiness at finite temperatures as well as a low melting point. Although the structure factors for the annealed structures are nearly identical, they are very different from those of either of the ideal structures. The computed IPs and EAs differ by less than 0.1 eV for weakly annealed cuboctahedral and icosahedral clusters, making the structural identification on the basis of IP and EA measurements very difficult. The quantum-mechanical results are also used to develop a classical potential for long-time molecular dynamics simulations of large clusters.

The variability of CD-24 7599 (V=11.48 mag) was discovered by JCC during observing run XCOV7 of the Whole Earth Telescope (WET, Nather et al. 1990) network in February, 1992. The star was observed as an additional target and 117 hours of high-quality temporal spectroscopic observations were obtained.Our analysis of these data revealed the presence of 7 independent pulsation modes between 27.0 and 38.1 cycles per day (313 – 441 μHz) with semiamplitudes of 2.1 – 10.2 milli-modulation amplitudes (mma). We showed that peaks at linear combination frequencies detected in the power spectra were not due to eigenmodes excited to visible amplitude by resonant mode coupling.

The methods for first-principles calculation of the structure and dynamics of clusters have now progressed to a point where clusters containing ca. 50 non-transition-metal atoms can be studied. As a paradigm, we studied the energetics of structural transformations in 13- and 55-atom Al clusters, which can assume both perfect icosahedral and cuboctahedral structures. Using the Car–Parrinello (quantum molecular dynamics) formalism, we found Al13 has a unique structure, a slightly distorted icosahedron, but Al55 has several inequivalent but energetically nearly degenerate structures. The degeneracy in Al55 is due to the short range of the effective interatomic interactions in a metallic cluster and should lead to floppiness at finite temperatures. A new accurate procedure for calculating ionization potentials (Ei) and electron affinities (Eea) within the Car–Parrinello formalism was developed and applied to Al clusters. Unfortunately, it appears that at least for some clusters, most notably for Al55, the Ei and Eea are very similar for different structural models of this cluster. A formulation and the first tests of a new multigrid-based method for real space electronic structure calculations are briefly described. This method should make possible calculations similar to the above for clusters containing transition metal and/or first-row atoms in the fairly near future.

We studied the first 100 consecutive patients (125 knees) to undergo knee arthroplasty with the original total condylar-I prosthesis for either osteoarthritis or osteonecrosis on the Knee Service at The Hospital for Special Surgery. They were followed for an average of 6.6 years (range, five to nine years), which is the longest follow-up of a total knee prosthesis that is still widely used in its original and unmodified form. At five to nine years of follow-up, eleven patients (fourteen knees) were dead and ten patients (eleven knees) could not be traced, leaving 100 knees (seventy-nine patients) for clinical evaluation. This included one knee from which the prosthesis was removed for sepsis at six months, four that were revised for pain, and two that were revised because of subluxation. Two patients had a loose tibial component. Sixty-four knees were rated as excellent and twenty-seven were rated as good. There were two fair and seven poor results. Detailed radiographic evaluation of the 100 knees showed that only minimum changes in the varus or valgus alignment or the fixation of the prosthetic components had occurred with time. At follow-up, 41 per cent of the tibial components showed some evidence of radiolucency, although with the exception of the two loose components just mentioned there were no complete or circumferential radiolucent lines. Most radiolucencies were present by the end of the first postoperative year, and in 81 per cent of the knees there was no further change. Although a special attempt was made to determine any evidence of wear of the polyethylene tibial component, we were unable to demonstrate unequivocal wear in any knee. Our experience had led us to conclude that the long-term success of current total knee designs will probably not be significantly affected by polyethylene wear or loss of component fixation. The majority of failures in our series were attributed to errors in surgical technique.

In seventeen children with catastrophic loss of the femoral head, the hip was salvaged by greater trochanteric arthroplasty. The average follow-up of these patients was eleven years, and fourteen patients were followed to skeletal maturity or longer. In Group I, consisting of four patients with greater trochanteric arthroplasty alone, good initial stability gradually deteriorated as subluxation occurred, accompanied by a proportionate return of abductor limp, loss of hip motion, and an increased rate of degenerative changes in the joint. Group II, consisting of eight patients who had either acetabuloplasty or innominate osteotomy in addition to greater trochanteric arthroplasty, had only slightly improved hip containment and results similar to those in Group I. Spontaneous ankylosis of the hip occurred in six of the patients in those two groups. The best results were obtained in five patients in Groups III and IV who had the procedure supplemented by proximal femoral varus osteotomy.

The method of characteristics and multiple-scaling perturbation techniques are used to study the space-charge instability of electron beams. It is found that the stable oscillating state (virtual cathode) created when the space-charge limit is exceeded is similar to a col­ lisionless shock wave. The oscillatory solution originates at the bifurcation point of two unstable steady states. Complementary behavior (virtual anode) results when an ion beam exceeds its space-charge limit. The virtual cathode can also exist in the presence of a neu­ tralizing heavy-ion background. The Pierce instability, where the electron and ion charge densities are equal, is a special case of this broader class. Estimates of the nonlinear growth rate of the instability at the space-charge limit are given.

A linear numerical analysis of the converging guide accelerator incorporating a radially inhomogeneous beam equilibrium and finite axial magnetic field is conducted. It is shown that these characteristics cannot explain the latest experimental results involving large amplitude waves. The slow phase velocity of these waves rely on nonlinear effects. A study of the adiabatic variation of wave amplitude in the accelerator indicates the importance of using high frequency waves for efficient operation.

The absorptivity of highly reflecting surfaces can be measured with relatively high sensitivity by using a nonresonant cavity made of the material of interest. The operation of such a cavity has been studied both theoretically and by computer simulation in order to establish the limits of applicability of the technique, and the results of this investigation are discussed. A system has been developed which allows the comparison of the absorptivity of a dilute alloy with that in the pure host metal and some preliminary results on CuNi are described.

The AutoAnalyzer has been modified to reduce specimen volume requirements to 0.1 ml. by replacing pump tubing. Alteration of procedure or reagents is not required for most analyses and sensitivity and accuracy of the micromethods are comparable to equivalent macromethods. Glucose, urea nitrogen, chloride, carbon dioxide, sodium, and potassium were measured in 1.0 ml. specimens of blood from rats using the microprocedures.

Injection of monoenergetic electron beams with uniform number density into an evacuated, straight-walled, equipotential cylindrical drift tubes has been modeled. An oscillating virtual cathode is produced by having the injected current exceed the space-charge limiting current of the drift tube. If the oscillation frequency of the virtual cathode exceeds the local beam plasma frequency a coherent traveling EM wave is launched with electric fields on the order of MeV/cm for an injected beam density of 1012 cm-3. Furthermore, in the absence of a strong axial magnetic field transmitted particles are autoaccelerated up to 3 times their initial kinetic energy.

Using our intermediate bandwidth photometric scanner, we have obtained light curve data at a range of spectral intervals for a number of close eclipsing binary systems. This paper reports briefly on the instrumentation system, the data obtained for two of the variables AE Phe and ε CrA, and a preliminary modelling of the light curves.

One-dimensional relativistic and electromagnetic simulations show the Plasma Beatwave Accelerator to be a viable approach to obtaining large accelerating fields. The plasma wave excited by Raman Forward Scattering has a longitudinal electric field on the order of 100 MeV/cm to 10 GeV/cm based on plasma densities of 1016 cm-3 to 1020 cm-3. The use of optical mixing to grow a plasma wave of the proper frequency above the noise level greatly reduces the laser intensity needed to drive the Raman instability. TeV energies for plasma electrons or preaccelerated charged particles in short distances appear feasible. Results where an injected electron beam is accelerated coherently from 1 MeV to 20 MeV in one millimeter are presented. Two-and three-dimensional effects must still be resolved.

We studied the first 100 consecutive patients (125 knees) to undergo knee arthroplasty with the original total condylar-I prosthesis for either osteoarthritis or osteonecrosis on the Knee Service at The Hospital for Special Surgery. They were followed for an average of 6.6 years (range, five to nine years), which is the longest follow-up of a total knee prosthesis that is still widely used in its original and unmodified form. At five to nine years of follow-up, eleven patients (fourteen knees) were dead and ten patients (eleven knees) could not be traced, leaving 100 knees (seventy-nine patients) for clinical evaluation. This included one knee from which the prosthesis was removed for sepsis at six months, four that were revised for pain, and two that were revised because of subluxation. Two patients had a loose tibial component. Sixty-four knees were rated as excellent and twenty-seven were rated as good. There were two fair and seven poor results. Detailed radiographic evaluation of the 100 knees showed that only minimum changes in the varus or valgus alignment or the fixation of the prosthetic components had occurred with time. At follow-up, 41 per cent of the tibial components showed some evidence of radiolucency, although with the exception of the two loose components just mentioned there were no complete or circumferential radiolucent lines. Most radiolucencies were present by the end of the first postoperative year, and in 81 per cent of the knees there was no further change. Although a special attempt was made to determine any evidence of wear of the polyethylene tibial component, we were unable to demonstrate unequivocal wear in any knee. Our experience had led us to conclude that the long-term success of current total knee designs will probably not be significantly affected by polyethylene wear or loss of component fixation. The majority of failures in our series were attributed to errors in surgical technique.

Forty-two digital neurorrhaphies utilizing contemporary techniques and suture material are reviewed. 17% regained near normal function. Another 30% regained imperfect, but very-pleasing function. Half of the patients were left with moderate to marked hypoaesthesia, but protective sensation. Protective sensation did not return to those nerves left unrepaired. Immediate repair did not allow better recovery than repair within six days. Delay up to eleven months did not obviate pleasing return of sensibility. Similarly, simultaneous tenorrhaphy did not seem to affect the quality of the result. Crushing, or avulsive injuries always resulted in “poor” return of sensibility. Testing two-point discrimination with the technique of Dellon will reveal recovery of epicritic sensation earlier than any other technique. After six months, few patients regained, or lost sensibility.The severed digital nerve must still carry a guarded prognosis in the adult.

Parallel intense laser beams, ωo/ ko and ω1, k1 shone on an underdense plasma with frequency separation equal to the plasma frequency, ωp, are capable of creating coherent large electrostatic fields and accelerating particles to high energies in large flux. The photon beatwave excites, through forward Raman scattering, a large amplitude plasma wave whose velocity is (ωo - ω1)/(ko — k1), close to c. The plasma wave attains electrostatic field strengths of Ez ≃ mcωp/e. This intense logitudinal field may be used to accelerate either preaccelerated charged particles, or plasma electrons.

In seventeen children with catastrophic loss of the femoral head, the hip was salvaged by greater trochanteric arthroplasty. The average follow-up of these patients was eleven years, and fourteen patients were followed to skeletal maturity or longer. In Group I, consisting of four patients with greater trochanteric arthroplasty alone, good initial stability gradually deteriorated as subluxation occurred, accompanied by a proportionate return of abductor limp, loss of hip motion, and an increased rate of degenerative changes in the joint. Group II, consisting of eight patients who had either acetabuloplasty or innominate osteotomy in addition to greater trochanteric arthroplasty, had only slightly improved hip containment and results similar to those in Group I. Spontaneous ankylosis of the hip occurred in six of the patients in those two groups. The best results were obtained in five patients in Groups III and IV who had the procedure supplemented by proximal femoral varus osteotomy.

Nonlinear frequency-shift effects in a regenerative oscillator driven by an external locking signal can be modeled in canonical fashion by inclusion in the Van der Pol equation of an additional cubic restoring force term. This can be seen from an analysis based on the complex Poynting's theorem and from the presence of an additional frequency shift term in the first-order phase evolution equation. This Van der Pol/Duffing equation was proposed by Lashinsky as a model of the generic regenerative oscillator. Both Van der Pol and Duffing nonlinearities are important in conventional high-power sources. In the case of microwave sources the linear and nonlinear behavior of the system is governed primarily by the interaction term which appears in the complex Poynting's theorem. This term is itself complex and in the small-signal limit the real and imaginary components are related by the Kramers-Kriinig relations. Extension into the large-signal regime thus naturally results in the appearance of both Van der Pol and Duffing contributions to the nonlinear coupled-mode equations. Approximate analytic and numerical studies of the Van der Pol/Duffing equation, with emphasis on phase-locking behavior, will be presented. Finally the connection between the general theory and intense microwave source behavior will be illustrated by an analysis of the elementary monotron.

The drug sample is dissolved in 0.2N HCl to yield a final concentration of 30 mug Fe/ml, an aliquot is reacted with alpha,alpha-dipyridyl, and the pH is adjusted with an acetate buffer. For Fe(II), the color intensity is measured at 523 nm. For total iron, ascorbic acid is added to a separate aliquot of the sample solution, reducing all the iron present to Fe(II), which is then reacted with alpha,alpha'-dipyridyl, diluted to volume, and read at 523 nm. The Fe(III) content is determined by subtracing Fe(II) from total iron. This method is applicable to iron-containing drugs and drug dosage forms.

A spectrophotometric method for determining Fe2+, Fe3+, and total Fe in drugs has been developed, using alpha,alpha'-dipyridyl as the colorimetric reagent. The method is applicable to tablets elixirs, injectables, and bulk powder. Eight collaborates analyzed a synthetic iron preparation and 7 commercial samples. For the synthetic iron preparation, the average recovery was 100.3% and the coefficient of variation was 1.02%. For 7 commercial samples, the average coefficient of variation was 1.44%. The method has been adopted as official first action.

We have studied cloth fiber cold cathode emitters and have found them to be superior to many other types of cold cathode emitters. In this paper, the characteristics of this type of cathode are presented.

A photometric system capable of simultaneous dual channel operation has been developed for use in NZ. The photometer head unit, developed and constructed by the University of Texas at Austin, permits simultaneous observation of two stars using suitable optics and mechanically coupled photomultiplier systems. The instrumentation and control system is centred around a DEC micro/PDP-11 computer and incorporates general purpose hardware and software developed specifically for the system.

A relativistic particle‐in‐cell simulation code has been used to study the space‐charge limiting currents of a solid and an annular relativistic electron beam. The resulting limiting currents are significantly higher than that given by the widely used Bogdankevich–Rukhadze interpolation formula.

We have used a scanning monochromator whose dispersive element was a circular interference filter to study the color variations of the variable stars 8 Sct and P Pup. The spectra were measured between 3700 A and 7300 A with a resolution of about 200 A and were recorded approximately every 10 minutes over several complete cycles of each star. The color changes found for 8 Sct were rather larger than have been reported previously, and indicated temperture changes of up to 400 K. Our measurements for p Pup, which does not show the beating common in 8 Sct stars, are consistent with those reported previously. Key words: scanning monochromator - 8 Scuti variables