Over the past century rigid bronchoscopy has been established as the main therapeutic means for central airway diseases of both benign and malignant aetiology. Its use requires general anaesthesia ...and mechanical ventilation usually in the form of manual or high-frequency jet ventilation. Techniques applied to regain patency of the central airways include mechanical debulking, thermal ablation (laser, electrocautery and argon plasma coagulation) and cryo-surgery. Each of these techniques have their advantages and limitations and best results can be attained by combining different modalities according to the type, location and extent of the airway blockage. If needed, deployment of airway endoprostheses (stents), as either fixed-diameter silicone or self-expandable metal stents, may preserve the airways patency often at the cost of several complications. Newer generation of customised stents either three-dimensional printed or drug-eluting stents constitute a promise for improved safety and efficacy results in the near future.
Treating central disease of benign or malignant aetiology, foreign body aspiration or massive bleeding in the airways requires a structured approach with combined techniques, a dedicated team of professionals and experience to treat eventual complications. Specific training and fellowships in interventional pulmonology should therefore be offered to those who wish to specialise in this field.
The mid-Pleistocene climate transition (MPT) is defined by the emergence of high amplitude, quasi-100ka glacial–interglacial cycles from a prior regime of more subtle 41kacycles. This change in ...periodicity and amplitude cannot be explained by a change in ‘external’ astronomical forcing. Here, we review and integrate published records of sea-surface temperatures (SSTs) to assess whether a common global expression of the MPT in the surface ocean can be recognized, and examine our findings in light of mechanisms proposed to explain climate system reorganization across the MPT. We show that glacial–interglacial variability in SSTs is superimposed upon a longer-term cooling trend in oceanographic systems spanning the low- to high-latitudes. Regional variability exists in the timing of the onset and magnitude of cooling but, in most cases, a long-term cooling trend begins or intensifies from ~1.2Ma (Marine Isotope Stage, MIS, 35-34). The SST cooling accompanies a long-term trend towards higher global ice volume as recorded in benthic foraminifera δ18O, but predates a step-like increase in δ18O at ~0.9Ma (MIS 24-22) that is argued to reflect expansion of continental ice-sheets. The strongest expression of Pleistocene cooling is found during glacial stages, whereas minor or negligible trends in interglacial temperatures are identified. However, pronounced cooling during both glacial and interglacial maxima is evident at 0.9Ma. Alongside the long-term SST cooling trends, quasi-100kacycles begin to emerge in both the SST and δ18O records at 1.2Ma, and become dominant with the expansion of the ice-sheets at 0.9Ma. We show that the intensified glacial-stage cooling is accompanied by evolving pCO2, abyssal ocean ventilation, atmospheric circulation and/or dust inputs to the Southern Ocean. These changes in diverse environmental parameters suggest that glacial climate boundary conditions evolved across the MPT. In turn, these modified boundary conditions may have altered climate sensitivity to orbital forcing by placing pre-existing ice-sheets closer to some threshold of climate–ice sheet response.
Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the ocean. Indeed, dust ...supply to the Southern Ocean increases during ice ages, and 'iron fertilization' of the subantarctic zone may have contributed up to 40 parts per million by volume (p.p.m.v.) of the decrease (80-100 p.p.m.v.) in atmospheric carbon dioxide observed during late Pleistocene glacial cycles. So far, however, the magnitude of Southern Ocean dust deposition in earlier times and its role in the development and evolution of Pleistocene glacial cycles have remained unclear. Here we report a high-resolution record of dust and iron supply to the Southern Ocean over the past four million years, derived from the analysis of marine sediments from ODP Site 1090, located in the Atlantic sector of the subantarctic zone. The close correspondence of our dust and iron deposition records with Antarctic ice core reconstructions of dust flux covering the past 800,000 years (refs 8, 9) indicates that both of these archives record large-scale deposition changes that should apply to most of the Southern Ocean, validating previous interpretations of the ice core data. The extension of the record beyond the interval covered by the Antarctic ice cores reveals that, in contrast to the relatively gradual intensification of glacial cycles over the past three million years, Southern Ocean dust and iron flux rose sharply at the Mid-Pleistocene climatic transition around 1.25 million years ago. This finding complements previous observations over late Pleistocene glacial cycles, providing new evidence of a tight connection between high dust input to the Southern Ocean and the emergence of the deep glaciations that characterize the past one million years of Earth history.
Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. ...Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought.
Determination of the relative inputs of aquatic autochthonous and terrestrial allochthonous organic matter into marine and lacustrine environments is essential to understanding the global carbon ...budget. A variety of proxies are used for this purpose, including the Branched and Isoprenoid Tetraether (BIT) index. This is calculated from the concentrations of branched glycerol dialkyl glycerol tetraethers (GDGTs), derived from unidentified terrestrial bacteria, and crenarchaeol, a marker for aquatic mesophile Thaumarchaeota (Crenarchaeota group I). As the index is a ratio, its value depends on both the crenarchaeol aquatic in situ production and the soil‐derived branched GDGT input. Therefore, the BIT index reflects not only changes in the input of terrestrial or soil organic matter but also relative variations in aquatic Thaumarchaeota abundance in the water column. In fact, we show that in oceanic and lacustrine settings, the BIT index can be dominated by the aquatic end‐member of the ratio. Consequently, the BIT index by itself can be an unreliable proxy to compare the input of terrestrial matter between sites and over time, and we propose that the quantification of branched GDGT fluxes or concentrations may instead be a better indicator of soil terrestrial inputs.
Key Points
The BIT is often uncorrelated to other terrestrial organic matter input proxies
Paleorecords reveal that the aquatic end‐member dominates the BIT
Branched GDGTs give a better estimate of the terrestrial organic matter input
The cold upwelling "tongue" of the eastern equatorial Pacific is a central energetic feature of the ocean, dominating both the mean state and temporal variability of climate in the tropics and ...beyond. Recent evidence for the development of the modern cold tongue during the Pliocene-Pleistocene transition has been explained as the result of extratropical cooling that drove a shoaling of the thermocline. We have found that the sub-Antarctic and sub-Arctic regions underwent substantial cooling nearly synchronous to the cold tongue development, thereby providing support for this hypothesis. In addition, we show that sub-Antarctic climate changed in its response to Earth's orbital variations, from a subtropical to a subpolar pattern, as expected if cooling shrank the warm-water sphere of the ocean and thus contracted the subtropical gyres.
In spite of the important role played by the Southern Ocean in global climate, the few existing paleoceanographic records in the east Pacific sector do not extend beyond one glacial‐interglacial ...cycle, hindering circumpolar comparison of past sea surface temperature (SST) evolution in the Southern Ocean. Here we present three alkenone‐based Pleistocene SST records from the subantarctic and subtropical Pacific. We use a regional core top calibration data set to constrain the choice of calibrations for paleo SST estimation. Our core top data confirm that the alkenone‐based UK37 and UK′37values correlate linearly with the SST, in a similar fashion as the most commonly used laboratory culture‐based calibrations even at low temperatures (down to ∼1°C), rendering these calibrations appropriate for application in the subantarctic Pacific. However, these alkenone indices yield diverging temporal trends in the Pleistocene SST records. On the basis of the better agreement withδ18O records and other SST records in the subantarctic Southern Ocean, we propose that the UK37 is a better index for SST reconstruction in this region than the more commonly used UK′37 index. The UK37‐derived SST records suggest glacial cooling of ∼8°C and ∼4°C in the subantarctic and subtropical Pacific, respectively. Such extent of subantarctic glacial cooling is comparable to that in other sectors of the Southern Ocean, indicating a uniform circumpolar cooling during the Pleistocene. Furthermore, our SST records also imply massive equatorward migrations of the Antarctic Circumpolar Current (ACC) frontal systems and an enhanced transport of ACC water to lower latitudes during glacials by the Peru‐Chile Current.
Key Points
UK37 is a better SST proxy than UK'37 in the Southern Ocean
Pleistocene glacial cooling of 8C in the subantarctic Pacific
Substantial equatorward shifts of ACC and intensified PCC during glacials
Segmentation of airways in Computed Tomography (CT) scans is a must for accurate support of diagnosis and intervention of many pulmonary disorders. In particular, lung cancer diagnosis would benefit ...from segmentations reaching most distal airways. We present a method that combines descriptors of bronchi local appearance and graph global structural analysis to fine-tune thresholds on the descriptors adapted for each bronchial level. We have compared our method to the top performers of the EXACT09 challenge and to a commercial software for biopsy planning evaluated in an own-collected data-base of high resolution CT scans acquired under different breathing conditions. Results on EXACT09 data show that our method provides a high leakage reduction with minimum loss in airway detection. Results on our data-base show the reliability across varying breathing conditions and a competitive performance for biopsy planning compared to a commercial solution.
The southeast Atlantic Ocean is dominated by two major oceanic systems: the Benguela Upwelling System, one of the world's most productive coastal upwelling cells and the Agulhas Leakage, which is ...important for transferring warm salty water from the Indian Ocean to the Atlantic Ocean. Here, we present a multi-proxy record of marine sediments from ODP Site 1087. We reconstruct sea surface temperatures (U37K′ and TEX86 indices), marine primary productivity (total chlorin and alkenone mass accumulation rates), and terrestrial inputs derived from southern Africa (Ti/Al and Ca/Ti via XRF scanning) to understand the evolution of the Southeast Atlantic Ocean since the late Pliocene. In the late Pliocene and early Pleistocene, ODP Site 1087 was situated within the Benguela Upwelling System, which was displaced southwards relative to present. We recognize a series of events in the proxy records at 3.3, 3.0, 2.2, 1.5, 0.9 and 0.6 Ma, which are interpreted to reflect a combination of changes in the location of major global wind and oceanic systems and local variations in the strength and/or position of the winds, which influence nutrient availability. Although there is a temporary SST cooling observed around the initiation of Northern Hemisphere glaciation (iNHG), proxy records from ODP Site 1087 show no clear climatic transition around 2.7 Ma but instead most of the changes occur before this time. This observation is significant because it has been previously suggested that there should be a change in the location and/or strength of upwelling associated with this climate transition. Rather, the main shifts at ODP Site 1087 occur at ca. 0.9 Ma and 0.6 Ma, associated with the early mid-Pleistocene transition (EMPT), with a clear loss of the previous upwelling-dominated regime. This observation raises the possibility that reorganisation of southeast Atlantic Ocean circulation towards modern conditions was tightly linked to the EMPT, but not to earlier climate transitions.
•First 3.5 Ma reconstruction and Southern Benguela Upwelling.•Evidence of increased terrestrial input during the Pliocene.•The proxies are stable over the iNGH.•There are major changes in the local systems after the EMPT (0.9 Ma).
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