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The origin of micrometeorites (MMs) from asteroids and comets is well-established, but the relative contribution from these two classes remains poorly resolved. Likewise, determining the precise origin of individual MMs is an open challenge. Here, cosmic-ray exposure ages are used to resolve the spatial origins of 12 MMs collected from urban areas and Antarctica. Their 26Al and 10Be concentration, produced during cosmic-ray irradiation in space, were measured by accelerator mass spectrometry. These data are compared to results from a model simulating the transport and irradiation of the MM precursors in space. This model, for the first time, considers a variety of orbits, precursor particle sizes, compositions and densities and incorporates non-isotropic solar and galactic cosmic-ray flux profiles, depth-dependent production rates, as well as spherical evaporation during atmospheric entry. While the origin for six MMs remains ambiguous, two MMs show a preferential tendency towards an origin in the Inner Solar System (Near Earth Objects to the Asteroid Belt) and four towards an origin in the Outer Solar System (Jupiter Family Comets to the Kuiper Belt). These findings challenge the notion that dust originating from the Outer Solar System is unlikely to survive long-term transport and delivery to the terrestrial planets. This article is part of the theme issue 'Dust in the Solar System and beyond'.

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Stone tools stratified in alluvium and loess at Korolevo, western Ukraine, have been studied by several research groups1-3 since the discovery of the site in the 1970s. Although Korolevo's importance to the European Palaeolithic is widely acknowledged, age constraints on the lowermost lithic artefacts have yet to be determined conclusively. Here, using two methods of burial dating with cosmogenic nuclides4,5, we report ages of 1.42 ± 0.10 million years and 1.42 ± 0.28 million years for the sedimentary unit that contains Mode-1-type lithic artefacts. Korolevo represents, to our knowledge, the earliest securely dated hominin presence in Europe, and bridges the spatial and temporal gap between the Caucasus (around 1.85-1.78 million years ago)6 and southwestern Europe (around 1.2-1.1 million years ago)7,8. Our findings advance the hypothesis that Europe was colonized from the east, and our analysis of habitat suitability9 suggests that early hominins exploited warm interglacial periods to disperse into higher latitudes and relatively continental sites-such as Korolevo-well before the Middle Pleistocene Transition.

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Isotopic ratios of radioactive releases into the environment are useful signatures for contamination source assessment. Uranium is known to behave conservatively in sea water so that a ratio of uranium trace isotopes may serve as a superior oceanographic tracer. Here we present data on the atomic [Formula: see text]U/[Formula: see text]U ratio analyzed in representative environmental samples finding ratios of (0.1-3.7)[Formula: see text]10[Formula: see text]. The ratios detected in compartments of the environment affected by releases of nuclear power production or by weapons fallout differ by one order of magnitude. Significant amounts of [Formula: see text]U were only released in nuclear weapons fallout, either produced by fast neutron reactions or directly by [Formula: see text]U-fueled devices. This makes the [Formula: see text]U/[Formula: see text]U ratio a promising new fingerprint for radioactive emissions. Our findings indicate a higher release of [Formula: see text]U by nuclear weapons tests before the maximum of global fallout in 1963, setting constraints on the design of the nuclear weapons employed.

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Extraoral open reduction and rigid fixation of mandibular subcondylar fractures is controversial among surgeons. An intraoral approach with a percutaneous trocar and miniplates demonstrated satisfactory reduction. This technique can be more easily performed than a preauricular or submandibular incision, and risk of facial nerve damage is diminished. Early function with proper vertical dimension was restored with minimal postoperative morbidity.

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Mechanical properties of blood clots stabilized with collagen (Pentapharm) and a gelatine (Gelastypt-M) sponge were compared with the help of thrombelastography and volumetric tests. The collagen songe was distinctly inferior to gelatine in stabilizing the clot against retraction. It appears that gelatine is a better material for filling large osseous defects that are subjected to mechanical stress.

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In vitro tests were carried out to determine whether the haemostyptic properties of a collagen monomer were lost during the manufacturing process. An increased recalcification time and thromboplastin time as well as failure of the thrombocytes to adhere to the collagen fibres were observed. This indicates that blood coagulation can be attributed only to mechanical irritation of the blood corpuscles and not to the properties of the collagen molecules.

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The only surgical means available up to now for treating obstructive sleep apnea syndrome (OSAS) consisted in uvulopalatopharyngoplasty (UPPP), which failed to produce satisfactory results. The ultima ratio frequently resorted to was tracheotomy with all its medical and social drawbacks. Complete advancement of the maxillomandibular complex opens up new avenues for the treatment of upper airways obstruction. The present report is on 13 patients operated for polysomnographically established OSA. The maxillomandibular complex was brought as far forward as possible and esthetically justifiable. This operation was occasionally combined with other procedures to enhance upper airways function, such as conchotomy, palatopharyngoplasty, chin graft and reduction of tongue size. In 85% of the cases the apnea and hypopnea index (RDI) could be lowered to below 10 per hour sleep, i.e. these patients were cured.

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The technique of harvesting auricular cartilage and its use in 22 patients (35 joints) is described. Follow-up was from 3 to 24 months. Pain relief was achieved in 90% of the cases. Function was equal or better to the preoperative situation in all cases.

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Twenty-three patients with obstructive sleep apnea syndrome (OSAS) documented by polysomnography underwent maxillomandibular advancement via Le Fort I, and sagittal ramus split osteotomies followed by rigid fixation with miniplates and bicortical screws. Partial turbinectomies and septal reconstruction were simultaneously performed. Pre- and post-operative cephalometric radiographs were analyzed by computer. Hyoid position and posterior airway space changes did not correlate with clinical success. The surgical success (respiratory disturbance index less than 10) with maxillomandibular advancement was 65%. The total desaturations below 90% greatly decreased. Ninety-six percent of patients were subjectively and objectively improved.

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A clinical follow-up of 238 patients confirmed the good results of root amputation with titanium pin for apical closure. An analysis of reoperations because of failure of primary surgery rendered similarly good results. Therefore the use of a titanium pin will not impair the success of secondary surgery for root amputation which shows good results most of the time anyway.

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The use of collagen as a bone substitute was examined in a clinical study involving 70 patients. In a standardized operation impacted mandibular third molars were removed simultaneously. Collagen fleece was implanted in one osseous defect while the other defect was packed with iodoform gauze. Postoperative pain, swelling and complications were analyzed. There were significant differences between the two methods. The use of collagen fleece to obturate bony defects following surgical removal of impacked molars appeared to be of no advantage. On the contrary, there was a considerably higher rate of postoperative bleeding and complications. This could probably be related to the poor stability of the implanted material.

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The bone lid method introduced by Lindorf (1974) was compared with a conservative procedure leaving a small defekt in the malar buttres. The operation is partly done with an endoscope. The results of 60 operated maxillary sinuses show a higher incidence of dysesthesia and postoperative discomfort in the bone lid method. Thus this method should in our opinion be reserved to special indications.

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Electron microscope studies made on biopsy samples of the human vocal cord from patients suffering from chronic hoarseness revealed pathological changes in both the collagen fibrils and the elastic fibres. There was splitting and fracturing of the collagen fibrils and lacuna or cyst formation in the elastic fibres, or even the complete fibre degeneration. Further investigations must be undertaken in order to establish whether the changes observed are of a primary or secondary nature.

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