Magnesium isotopes of the bulk solar wind from Genesis diamond-like carbon films.

NASA's Genesis Mission returned solar wind (SW) to the Earth for analysis to derive the composition of the solar photosphere from solar material. SW analyses control the precision of the derived solar compositions, but their ultimate accuracy is limited by the theoretical or empirical models of fractionation due to SW formation. Mg isotopes are "ground truth" for these models since, except for CAIs, planetary materials have a uniform Mg isotopic composition (within ≤1‰) so any significant isotopic fractionation of SW Mg is primarily that of SW formation and subsequent acceleration through the corona. This study analyzed Mg isotopes in a bulk SW diamond-like carbon (DLC) film on silicon collector returned by the Genesis Mission. A novel data reduction technique was required to account for variable ion yield and instrumental mass fractionation (IMF) in the DLC. The resulting SW Mg fractionation relative to the DSM-3 laboratory standard was (-14.4‰, -30.2‰) ± (4.1‰, 5.5‰), where the uncertainty is 2Æ¡ SE of the data combined with a 2.5‰ (total) error in the IMF determination. Two of the SW fractionation models considered generally agreed with our data. Their possible ramifications are discussed for O isotopes based on the CAI nebular composition of McKeegan et al. (2011).

Fine-grained Material Associated with a Large Sulfide returned from Comet 81P/Wild 2.

In a consortium analysis of a large particle captured from the coma of comet 81P/Wild 2 by the Stardust spacecraft, we report the discovery of a field of fine-grained material (FGM) in contact with a large sulfide particle. The FGM was partially located in an embayment in the sulfide. As a consequence, some of the FGM appears to have been protected from damage during hypervelocity capture in aerogel. Some of the FGM particles are indistinguishable in their characteristics from common components of chondritic-porous interplanetary dust particles (CP-IDPs), including glass with embedded metals and sulfides (GEMS) and equilibrated aggregates (EAs). The sulfide exhibits surprising Ni-rich lamellae, which may indicate that this particle experienced a long-duration heating event after its formation but before incorporation into Wild 2.

Control of near-infrared supercontinuum bandwidth by adjusting pump pulse duration.

We experimentally and numerically investigated the impact of input pump pulse duration on the near-infrared bandwidth of supercontinuum generation in a photonic crystal fiber. We continuously stretched the temporal duration of the input pump laser (centered at 1030 nm) pulses from 500 fs up to 10 ps, while keeping fixed the pump peak power. We observed that the long-wavelength edge of the supercontinuum spectrum is increased by 200 nm as the pump pulse duration grows from 500 fs to 10 ps. We provide a quantitative fit of the experimental results by means of numerical simulations. Moreover, we have explained the observed spectral broadening enhancement induced by pump pulse energy by developing an approximate yet fully analytical model for soliton energy exchange through a series of collisions in the presence of stimulated Raman scattering.

Tektites that were partially plastic after completion of surface sculpturing.

Among the 50,000 tektites collected over an 8-year period as part of a representative collection of the indochinities in an area near Dalat, South Vietnam, several individual ones have been found that show evidence of having been internally plastic after surface sculpturing was essentially completed. Two drops, which were bent after having formed a thin exterior skin or crust, exhibit surface breaks and stretching of their plastic interiors within the breaks. The lack of deep sculpturing in this interior stretched area, coupled with twisting within the break on one of them, indicates that the surface features on these tektites were formed in the atmosphere and not by etching by soil acids, as had been widely believed.

Presolar corundum and spinel in ordinary chondrites: origins from AGB stars and a supernova.

On the basis of anomalous isotopic compositions of oxygen and magnesium, 14 oxide grains from two primitive meteorites (Bishunpur and Semarkona) have been identified as circumstellar condensates. One corundum grain has a high 18O/16O ratio and isotopic compositions of magnesium, calcium, and titanium that are compatible with a formation in ejecta of a type II supernova that was about 15 times the mass of the sun. The other grains have oxygen, magnesium, and titanium compositions that are consistent with a formation around asymptotic giant branch (AGB) stars with a range of mass and initial composition. The large range of aluminum/magnesium in circumstellar corundum and spinel is considered to reflect various stages of back-reaction between condensed corundum and gaseous magnesium in cooling stellar ejecta.

DETERMINING THE ELEMENTAL AND ISOTOPIC COMPOSITION OF THE PRESOLAR NEBULA FROM GENESIS DATA ANALYSIS: THE CASE OF OXYGEN.

We compare element and isotopic fractionations measured in solar wind samples collected by NASA's Genesis mission with those predicted from models incorporating both the ponderomotive force in the chromosphere and conservation of the first adiabatic invariant in the low corona. Generally good agreement is found, suggesting that these factors are consistent with the process of solar wind fractionation. Based on bulk wind measurements, we also consider in more detail the isotopic and elemental abundances of O. We find mild support for an O abundance in the range 8.75 - 8.83, with a value as low as 8.69 disfavored. A stronger conclusion must await solar wind regime specific measurements from the Genesis samples.

A new type of solar-system material recovered from Ordovician marine limestone.

From mid-Ordovician ∼470 Myr-old limestone >100 fossil L-chondritic meteorites have been recovered, representing the markedly enhanced flux of meteorites to Earth following the breakup of the L-chondrite parent body. Recently one anomalous meteorite, Österplana 065 (Öst 65), was found in the same beds that yield L chondrites. The cosmic-ray exposure age of Öst 65 shows that it may be a fragment of the impactor that broke up the L-chondrite parent body. Here we show that in a chromium versus oxygen-isotope plot Öst 65 falls outside all fields encompassing the known meteorite types. This may be the first documented example of an 'extinct' meteorite, that is, a meteorite type that does not fall on Earth today because its parent body has been consumed by collisions. The meteorites found on Earth today apparently do not give a full representation of the kind of bodies in the asteroid belt ∼500 Myr ago.

Double-blind crossover study with levorotatory form of hydroxytryptophan in patients with degenerative cerebellar diseases.

OBJECTIVE: To determine whether treatment with the levorotatory form of hydroxytryptophan (L-5-hydroxytryptophan), a controversial experimental drug, can improve the conditions of patients with ataxia. DESIGN: A double-blind crossover study with the levorotatory form of hydroxytryptophan was performed in 39 patients with degenerative cerebellar diseases. SETTING: Patients were selected from an ongoing prospective follow-up study at two university hospitals. PATIENTS: We studied 19 patients with Friedreich's ataxia, 13 with cerebellar atrophy, and seven with olivoponto-cerebellar atrophy. INTERVENTION: The levorotatory form of hydroxytryptophan was given orally in a dose of 1000 mg/d. Each treatment phase, with the levorotatory form of hydroxytryptophan or the placebo, lasted 10 months, after which the treatment of patients was crossed over to the other phase. MAIN OUTCOME MEASURES: Ataxia was documented and quantified by using a clinical score, posturography, and measurement of grip force and the rapid-syllable repetition rate. RESULT: The levorotatory form of hydroxytryptophan had no significant effect on cerebellar symptoms. CONCLUSION: Long-term treatment with a high dose of the levorotatory form of hydroxytryptophan does not improve the conditions of patients with ataxia.

Determination of cell-bound Fc receptors using a cell adherence test (CAT).

The determination of membrane-bound Fc receptors as rosette forming cells with antibody-coated erythrocytes (EA-RFC) is a tedious and time consuming method. Here, we describe a modification of the assay delineated by Eisenbarth et al. (J. Immunol. Methods (1980) 39, 387) for the detection of Fc receptors on cell surfaces. V-shaped microtiter plates were coated with an antigen (e.g., fluorescein isothiocyanate (FITC) coupled to bovine serum albumin (BSA] and subsequently with monoclonal anti-FITC antibodies of different isotypes. Cells to be tested were added, incubated for a short time or centrifuged immediately. Cells expressing FcR, became bound to the flanks of the V-shaped wells, whereas cells lacking the receptor were pelleted to the tip of the well. This cell adherence test (CAT) is independent of the agglutinating abilities of the antibodies, and since it is very fast and highly reproducible, large numbers of different cells can be screened for FcR expression. Anti-receptor antibodies can also be tested for their binding to FcR.

Follow-up of neurophysiological tests and CT in late-onset cerebellar ataxia and multiple system atrophy.

The follow-up of neurophysiological tests (brain-stem auditory evoked potentials; blink reflex; sensory, motor and visual evoked potentials) and CT was investigated in 21 patients with late-onset cerebellar ataxia (CA) or multiple system atrophy. The study included an initial investigation and a follow-up examination on average 25.3 months later (minimum 8, maximum 36). Patients were divided into four groups: (1) those with pure CA after a minimum course of 5 years; (2) those with pure CA with pathological neurophysiological findings at the last examination; (3) those who at the first examination clinically presented with pure CA, but at the last examination were seen to have developed a multisystem disorder; (4) those with multiple system atrophy (mostly olivopontocerebellar atrophy) presenting additional non-cerebellar signs of involvement. Conforming to a strict interpretation of pure CA, group 1 patients invariably exhibited normal neurophysiological findings at all examinations. All patients in group 4, except for 2 only at the first examination, showed pathological changes in at least one of the neurophysiological tests. The main conclusion of this paper is that individuals who according to clinical criteria were initially classified as having CA but finally developed a multisystem disorder already had pathological neurophysiological findings at the initial examination (group 3). The increasing frequency of pathology in the several neurophysiological tests together with the progression of the disease is obviously of prognostic significance. CT revealed cerebellar atrophy without apparent involvement of brain-stem structures in all patients with CA; the majority of patients with multiple system atrophy also had atrophy of the brain-stem, pointing to olivopontocerebellar atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of slipped capital femoral epiphysis. Spica-cast immobilization.

Thirty-two patients (thirty-seven hips) who had a so-called acute-on-chronic or chronic slipped capital femoral epiphysis were treated with traction for relief of symptoms and then with immobilization in a spica cast for eight to sixteen weeks. The disappearance on radiographs of a metaphyseal juxtaphyseal radiolucency, rather than closure of the physis, was used as the criterion for removing the cast. In one (3 per cent) of the thirty-seven hips, the slip progressed; possibly this could have been prevented by keeping the cast on for a longer period of time. Narrowing of the cartilage space was seen after treatment in a cast in seven (19 per cent) of the thirty-seven hips. In five of these seven hips, this was true chondrolysis; in one, the diagnosis of chondrolysis had been apparent before treatment. Avascular necrosis did not develop as a result of treatment in any patient. Treatment in a spica cast should be considered as an alternative for patients who have an acute-on-chronic or chronic slipped capital femoral epiphysis.

Coronal decompensation produced by Cotrel-Dubousset "derotation" maneuver for idiopathic right thoracic scoliosis.

From 1985 to 1987, 82 patients with idiopathic scoliosis followed 12 to 44 months underwent selective fusion and correction of their right thoracic curves by Cotrel-Dubousset instrumentation using the "derotation" maneuver. Preoperative, postoperative, and follow-up standing anteroposterior roentgenograms of the spine were analyzed. For curves in which there was deviation from the midline (plumb line) and rotation of the lumbar segments, an increased incidence of decompensation was produced after surgery, when posterior Cotrel-Dubousset instrumentation and fusion were carried to the "stable" vertebra with one rod bend and hook alignment on the left sided derotation rod. Previous guidelines established for selective fusion with conventional posterior instrumentation (Harrington or Luque rods) may not be applicable to derotation with Cotrel-Dubousset instrumentation.

Sagittal plane analysis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

One hundred sixty patients with idiopathic scoliosis underwent preoperative and postoperative sagittal plane analysis of the thoracic spine, thoracolumbar junction, and lumbar spine. The data suggest that mild to moderate improvements in thoracic hypokyphosis are possible. When crossing the thoracolumbar junction, reversal of rod bend and reversal of hooks on the derotation rod appears to provide the most physiologic sagittal contour. Cotrel-Dubousset instrumentation to the mid and distal lumbar spine can preserve and, at times, enhance lumbar lordosis.

Sagittal plane analysis in idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

One hundred sixty patients with idiopathic scoliosis treated with Cotrel-Dubousset instrumentation (CDI) underwent preoperative and postoperative sagittal plane analysis of the thoracic spine, thoracolumbar junction, and lumbar spine. The data suggest that mild to moderate improvements in thoracic hypokyphosis are possible. When crossing the thoracolumbar junction, reversal of rod bend and reversal of hooks on the derotation rod appear to provide the most physiologic sagittal contour. Cotrel-Dubousset instrumentation to the mid and distal lumbar spine can preserve and, at times, enhance lumbar lordosis.

Are there indications for partial rib resection in patients with adolescent idiopathic scoliosis treated with Cotrel-Dubousset instrumentation?

In adolescent idiopathic scoliosis the cosmetically unacceptable rib prominence is one of the main reasons patients seek treatment. Ninety-eight patients were reviewed with Cotrel-Dubousset (CD) instrumentation (average follow-up, 27 months; average preoperative curve, 53 degrees) and 27 patients with Harrington instrumentation and rib resection (average follow-up, 43 months; average preoperative curve, 52 degrees). Of the 98 patients who had CD instrumentation, 15 underwent concomitant rib resection. Of the 83 patients without rib resection, 71 (72%) were rated satisfactory and 12 unsatisfactory by cosmetic criteria based on residual rib deformity. These results were compared to those of 27 patients receiving Harrington rod instrumentation and rib resection, of whom 23 (85%) were rated as satisfactory. All 15 patients with CD and rib resection were rated satisfactory. The CD patients were then redivided into two groups (rib resection indicated or rib resection not indicated) as follows: the 12 unsatisfactory CD patients without rib resection (in whom a rib resection should have been done) were grouped with the 15 CD patients who underwent rib resection, for a total of 27 rib resections indicated, or 28%. This group was compared to the 71 satisfactory CD patients without rib resection (rib resection not indicated). Patients with a rib prominence of > 15 degrees preoperatively had or should have had a rib resection. Patients with a higher chance of needing rib resection included those with a curve severity greater than 60 degrees, curve flexibility less than 20%, a preoperative rib prominence > 10 degrees, or intraoperative curve correction of less than 50%.

Proximal kyphosis after posterior spinal fusion in patients with idiopathic scoliosis.

STUDY DESIGN: For this retrospective study, preoperative and postoperative radiographs of posterior spinal fusions for idiopathic scoliosis were reviewed. OBJECTIVES: To determine the prevalence and possible causes of proximal kyphosis after posterior spinal fusion for idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Proximal kyphosis has been anecdotally noted after the insertion of Harrington rods and after use of the new posterior multisegmented hook/rod systems. In this study no attempt was made to determine whether this condition is painful or an adverse outcome for the patient or just a radiographic abnormality; however, it is suspected that this may be a problem in the long term, and it may be worthwhile to try to avoid it if predictive values can be ascertained. METHODS: Patients with adolescent idiopathic scoliosis who had undergone posterior spinal fusion not extending above T3 with good-quality radiographs of the proximal thoracic spine and a minimum 2-year follow-up were studied. Of the 106 patients who underwent posterior spinal fusion from 1990 through 1994, 69 met the inclusion criteria. Abnormal kyphosis from T2 to the proximal level of the instrumented fusion was defined as kyphosis of more than 5 degrees above the summed normal angular segments. RESULTS: Of 69 patients, 37 (54%) had normal proximal kyphosis, and 32 (46%) of the 69 were defined as having abnormal proximal kyphosis. In the 32 patients with abnormal proximal kyphosis, the measurement from T2 to the fusion was 10.3 degrees before surgery and 21.2 degrees after surgery. The normal group had kyphosis measuring 2.7 degrees from T2 to fusion before surgery and 5.3 degrees after surgery (P < 0.00001). Junctional kyphosis in the kyphosis group measured 6.5 degrees before surgery and 12.6 degrees after surgery, compared with normal kyphosis of 1.7 degrees and 2.6 degrees, respectively (P < 0.00001). When analyzing who would develop proximal kyphosis, preoperative one-level junctional kyphosis of more than 5 degrees above the proposed proximal instrumented vertebrae was shown to have the highest sensitivity (78%) and specificity (84%). CONCLUSIONS: In this study, 32 (46%) of 69 patients had abnormal proximal kyphosis after undergoing posterior spinal fusion. A preoperative junctional kyphosis of more than 5 degrees above the proposed proximal instrumented vertebrae indicates that extending the fusion to a higher level in the thoracic spine would be beneficial in avoiding this problem.

Do radiographic parameters correlate with clinical outcomes in adolescent idiopathic scoliosis?

STUDY DESIGN: A radiographic assessment has been developed to include coronal, sagittal, and axial parameters. OBJECTIVE: To determine the correlation of postoperative radiographic results and percentage postoperative radiographic improvement with patient clinical self-assessment. SUMMARY OF BACKGROUND DATA: With the increasing interest in outcome studies, the authors wanted to determine whether Scoliosis Research Society clinical questionnaire results would correlate with objective radiographic improvement. INCLUSION CRITERIA: adolescent idiopathic scoliosis treated with anterior or posterior instrumentation, a solid fusion, minimum 2-year follow-up, and a completed postoperative Scoliosis Research Society questionnaire. Seventy-eight patients met the criteria. Measurements included in the radiographic score: Cobb angles of the coronal curve, C7 to the center sacral vertical line, apical translation, apical vertebral rotation, T1 rib angle, end-instrumented vertebrae angulation, angulation of the disc below the end-instrumented vertebra, and curve type. Sagittal measurements included T2-T12, T5-T12, T2-T5, T12-L2, and L1-S1. RESULTS: The preoperative radiographic score of these 78 patients was mean 60.1 +/- 9.7 (range 41-88, maximum radiographic score, 100). The 2-year postoperative radiographic score was mean 83.8 +/- 8.8 (range, 65-100). The median Scoliosis Research Society questionnaire score was 98 +/- 12.3 (range, 58-116, maximum score, 125, showing that the patient is highly satisfied and asymptomatic). The postoperative radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.04 (P = 0.68, little or no correlation throughout). Percentage improvement of the radiographic score versus the questionnaire score showed a Spearman rank correlation of 0.1 (P = 0.38, little or no correlation throughout). CONCLUSION: In this initial group of patients, the radiographic assessment shows a significant improvement between preoperative and 2-year postoperative scores. However, little correlation between the radiographic assessment and the questionnaire scores was found in this adolescent population, suggesting that separate analyses of radiographic and clinical outcome data are required when evaluating results of postoperative scoliosis surgery.

A draping technique for spinal surgery using the Stagnara wake-up test.

This draping procedure has been used at our hospital in more than 200 spinal procedures. The main advantage is that the surgeon has a direct view of the feet and can personally observe the results of the test. The draping procedure is simple, and it eliminates the chance of contamination when lifting the drapes. No disadvantages have been noted to date, and there have been no infections.