Surgically assisted rapid maxillary expansion (SARME) has become a widely used and acceptable means to expand the maxilla in adolescents and adult patients. The method takes advantage of bone formation at the maxillary edges of the midline, while they are separated by an external force. The purpose of the present retrospective investigation was to evaluate the feasibility and long-term stability of maxillary expansion in patients in whom lateral pre-expansion osteotomy had been performed. The subjects were 20 patients (14 females, six males, mean age 30.6 years, range 16.2-44.2 years) whose malocclusions were treated solely or partly with SARME during 1988-1996. Two orthodontists carried out the post-orthodontic expansion treatment. The surgical technique followed a minimally invasive osteotomy on the lateral maxillary walls. Study models were obtained before surgery (T1), once expansion and the following orthodontic treatment were completed, before possible second-stage osteotomy (T2), and at long-term follow-up (T3). Using the study models, the width of the dental arch was measured with a digital sliding calliper. In addition, transverse occlusal relationships were examined at each time point. The results indicated that (1) SARME is possible when the minimally invasive operation technique is used, (2) long-term stability of maxillary expansion following the present technique compares favourably with the widening and stability achieved with other, more invasive, osteotomies. With age, several possible uncertainties are introduced to affect the course of SARME adversely. Therefore, more extensive osteotomies can be recommended in older patients.

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This paper presents an integrated analysis of GOES 6, 7 and neutron monitor observations of solar cosmic-ray event following the 1990 May 24 solar flare. We have used a model which includes particle injection at the Sun and at the interplanetary shock front and particle propagation through the interplanetary medium. The model does not attempt to simulate the physical processes of coronal transport and shock acceleration, therefore the injections at the Sun and at the shock are represented by source functions in the particle transport equation. By fitting anisotropy and angleaverage intensity profiles of high-energy (>30 MeV) protons as derived from the model to the ones observed by neutron monitors and at GOES 6 and 7, we have determined the parameters of particle transport, the injection rate and spectrum at the source. We have made a direct fit of uncorrected GOES data with both primary and secondary proton channels taken into account.The 1990 May 24-26 energetic proton event had a double-peaked temporal structure at energies 100 MeV. The Moreton (shock) wave nearby the 'flare core' was seen clearly before the first injection of accelerated particles into the interplanetary medium. Some (correlated with this shock) acceleration mechanism which operates in the solar corona at a height up to one solar radius is regarded as a source of the first (prompt) increase in GOES and neutron monitor counting rates. The proton injection spectrum during this increase is found to be hard (spectral index "7 ~ 1.6) at lower energies (,-~ 30 MeV) with a rapid steepening above 300 MeV. Large values of the mean free path (), ~ 1.8 AU for 1 GV protons in the vicinity of the Earth) led to a high anisotropy of arriving protons. The second (delayed) proton increase was presumably produced by acceleration/injection of particles by an interplanetary shock wave at height of ~ 10 solar radii. Our analysis of the 1990 May 24-26 event is in favour of the general idea that a number of components of energetic particles may be produced while the flare process develops towards larger spatial/temporal scales.

Abstract. The onset of the >10-MeV proton event of August 13-14, 1996, revealed a velocity dispersion, which is a signature of its solar origin, but no associated soft X ray flare was observed. The LASCO CME observations, the presence of AR 7981 beyond the west limb, and type II and IV radio burst timing with respect to the proton event onset indicate that the parent solar eruption may be centered on the back side of the Sun, at ---150øW. In such a case, expanding CME-associated wave can reach the Earth-connected interplanetary magnetic field line in ---1 hour and so give rise to the > 10-MeV proton event observed with the Energetic and Relativistic Nuclei and Electron (ERNE) instrument onboard SOHO. We verify this hypothesis against observational data and conclude that a solar back side eruption is the most plausible explanation of the August 13, 1996, event. We compare the August 13, 1996, event with events associated with Earth directed CMEs and show that the August 13, 1996, event reveals many properties common to >10-MeV proton events originating from solar eruptions centered ---90 ø away from the root of the Earth-connected interplanetary magnetic field line. In such events, the first detected protons are released ---1 hour after the start time of type II and IV radio bursts. The first injection spectrum is essentially harder than the spectrum at the intensity maximum; that is, the hard but less intensive proton production is followed by the major soft-spectrum production when CME expands farther from the Sun. sion that the interplanetary CME-driven shocks mainly accelerate seed particles originating from the solar corona. This may imply, when studying the efficiency of proton production, that more attention must be paid to the beginning of the event when the CME expands near the Sun.A careful study of the commencement of the August 13, 1996, particle event is important also because there were no signatures of a parent eruption in the GOES soft X ray data.

[1] We present the first modeling of solar energetic particle (SEP) events inside corotating compression regions. We consider gradual compressions in the interplanetary magnetic field brought on by interaction of the solar wind streams of different speed. The compression model is similar to that previously suggested for the acceleration of lowenergy particles associated with corotating interaction regions (CIRs). In the framework of focused transport, we perform Monte Carlo simulations of the SEP propagation, adiabatic deceleration and reacceleration. A trap-like structure of the interplanetary magnetic field modifies the SEP intensity-time profiles, energy spectra, and anisotropy. Particle diffusion and adiabatic deceleration are typically reduced. For this reason, at a corotating vantage point the SEP event development after the intensity maximum is slower than would be expected based on the modeling in the standard, Archimedean spiral field. At the noncorotating spacecraft the magnetic tube convection past the observer becomes more important. The numerical model forms a basis on which to interpret SEP observations made by present and future spacecrafts at the longitude-dependent speed of solar wind. In particular, the modeling results are similar to the patterns observed with the ERNE particle telescope on board SOHO in August 1996. In the proton anisotropy data, we find a signature of the magnetic mirror associated with the CIR. A relation is established between the spectra observed at 1 AU and the SEP injection spectrum near the Sun.

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Abstract. We consider the prolonged injection of the high-energy (>10 MeV) protons during the three successive events observed by GOES in October 1989. We apply a solar-rotation-stereoscopy approach to study the injection of the accelerated particles from the CMEdriven interplanetary shock waves in order to ®nd out how the eectiveness of the particle acceleration and/or escape depends on the angular distance from the shock axis. We use an empirical model for the proton injection at the shock and a standard model of the interplanetary transport. The model can reproduce rather well the observed intensity±time pro®les of the October 1989 events. The deduced proton injection rate is highest at the nose of the shock; the injection spectrum is always harder near the Sun. The results seem to be consistent with the scheme that the CME-driven interplanetary shock waves accelerate a seed particle population of coronal origin.

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