Western equatorial African forest-savanna mosaics: a legacy of late Holocene climatic change?

Past vegetation and climate changes reconstructed using two pollen records from Lakes Maridor and Nguène, located in the coastal savannas and inland rainforest of Gabon, respectively, provide new insights into the environmental history of western equatorial African rainforests during the last 4500 cal yr BP. These pollen records indicate that the coastal savannas of western equatorial Africa did not exist during the mid-Holocene and instead the region was covered by evergreen rainforests. From ca. 4000 cal yr BP a progressive decline of inland evergreen rainforest, accompanied by the expansion of semi-deciduous rainforest, occurred synchronously with grassland colonisation in the coastal region of Gabon. The contraction of moist evergreen rainforest and the establishment of coastal savannas in Gabon suggest decreasing humidity from ca. 4000 cal yr BP. The marked reduction in evergreen rainforest and subsequent savanna expansion was followed from 2700 cal yr BP by the colonization of secondary forests dominated by the palm, <i>Elaeis guineensis</i>, and the shrub, <i>Alchornea cordifolia</i> (Euphorbiaceae). A return to wetter climatic conditions from about 1400 cal yr BP led to the renewed spread of evergreen rainforest inland, whereas a forest-savanna mosaic still persists in the coastal region. There is no evidence to suggest that the major environmental changes observed were driven by human impact

Assessment of vocal cord nodules: A case study in speech processing by using Hilbert-Huang Transform

Vocal cord nodules represent a pathological condition for which the growth of unnatural masses on vocal folds affects the patients. Among other effects, changes in the vocal cords' overall mass and stiffness alter their vibratory behaviour, thus changing the vocal emission generated by them. This causes dysphonia, i.e. abnormalities in the patients' voice, which can be analysed and inspected via audio signals. However, the evaluation of voice condition through speech processing is not a trivial task, as standard methods based on the Fourier Transform, fail to fit the non-stationary nature of vocal signals. In this study, four audio tracks, provided by a volunteer patient, whose vocal fold nodules have been surgically removed, were analysed using a relatively new technique: the Hilbert-Huang Transform (HHT) via Empirical Mode Decomposition (EMD); specifically, by using the CEEMDAN (Complete Ensemble EMD with Adaptive Noise) algorithm. This method has been applied here to speech signals, which were recorded before removal surgery and during convalescence, to investigate specific trends. Possibilities offered by the HHT are exposed, but also some limitations of decomposing the signals into so-called intrinsic mode functions (IMFs) are highlighted. The results of these preliminary studies are intended to be a basis for the development of new viable alternatives to the softwares currently used for the analysis and evaluation of pathological voice

Optegnelser af presten Oluf Bentsen Mandal for aarene 1625-36.

Anthropogenic radionuclide inputs in the Loire estuary (French Atlantic coast) consist of radioactive releases from 14 nuclear reactors located along the Loire river basin, and of fallout from nuclear weapon tests and from the Tchernobyl accident. To estimate to what extent radionuclides associated with sediment accumulate in the estuary, three complementary approaches were used: field surveys, laboratory experiments and numerical modelling. Sampling of bottom sediments, water and suspended solids was carried out at 8 different dates over a 15 month-period. Analysis covered 14C, 90Sr, 3H, the naturally occurring gamma-emitters (uranium and thorium decay chains, 7Be and 40K), and the artificial gamma emitters (mainly cobalt and cesium isotopes). To gain information on the contamination history of the estuary, sediment cores were also collected at different locations inside and outside the estuarine zone. Processes of radionuclide transport and exchange between dissolved and particulate phases were included in a previously developed estuary specific 2D-hydrodynamic model. Equations of sorption and desorption kinetics were derived from laboratory experiments conducted at different salinities. Simulations carried out for two river discharge conditions (low summer flow, high winter flow) allowed to follow radionuclide desorption in the estuary. For long term simulations, a simplified model was developed. It provided estimates of the amount of radionuclides expelled out of the estuary under dissolved and particulate forms, of the transit time for both forms and of the variations in radionuclides concentrations in the fluid mud. Based on computed results and observations, contributions from different origins (natural, military, industrial, marine, continental) to the inventory of radioactivity in the estuary are presented

Sea surface temperatures of the western Arabian Sea during the last deglaciation.

In this study we present a sea surface temperature (SST) record from the western Arabian Sea for the last\ud 20,000 years. We produced centennial-scale d18O and Mg/Ca SST time series of core NIOP929 with focus on\ud the glacial-interglacial transition. The western Arabian Sea is influenced by the seasonal NE and SW monsoon\ud wind systems. Lowest SSTs occur during the SW monsoon season because of upwelling of cold water, and\ud highest SSTs can be found in the low-productivity intermonsoon season. The Mg/Ca-based temperature record\ud reflects the integrated SST of the SW and NE monsoon seasons. The results show a glacial-interglacial SST\ud difference of 2C, which is corroborated by findings from other Arabian Sea cores. At 19 ka B.P. a yet\ud undescribed warm event of several hundred years duration is found, which is also reflected in the d18O record. A\ud second centennial-scale high SST/low d18O event is observed at 17 ka B.P. This event forms the onset of the\ud stepwise yet persistent trend toward Holocene temperatures. Highest Mg/Ca-derived SSTs in the NIOP929\ud record occurred between 13 and 10 ka B.P. Interglacial SST is 24C, indicating influence of upwelling. The\ud onset of Arabian Sea warming occurs when the North Atlantic is experiencing minimum temperatures. The rapid\ud temperature variations at 19, 17, and 13 ka B.P. are difficult to explain with monsoon changes alone and are\ud most likely also linked to regional hydrographic changes, such as trade wind induced variations in warm water\ud advection

Climatic and cultural changes in the west Congo Basin forests over the past 5000 years

Central Africa includes the world's second largest rainforest block. The ecology of the region remains poorly understood, as does its vegetation and archaeological history. However, over the past 20 years, multidisciplinary scientific programmes have enhanced knowledge of old human presence and palaeoenvironments in the forestry block of Central Africa. This first regional synthesis documents significant cultural changes over the past five millennia and describes how they are linked to climate. It is now well documented that climatic conditions in the African tropics underwent significant changes throughout this period and here we demonstrate that corresponding shifts in human demography have had a strong influence on the forests. The most influential event was the decline of the strong African monsoon in the Late Holocene, resulting in serious disturbance of the forest block around 3500 BP. During the same period, populations from the north settled in the forest zone; they mastered new technologies such as pottery and fabrication of polished stone tools, and seem to have practised agriculture. The opening up of forests from 2500 BP favoured the arrival of metallurgist populations that impacted the forest. During this long period (2500–1400 BP), a remarkable increase of archaeological sites is an indication of a demographic explosion of metallurgist populations. Paradoxically, we have found evidence of pearl millet (Pennisetum glaucum) cultivation in the forest around 2200 BP, implying a more arid context. While Early Iron Age sites (prior to 1400 BP) and recent pre-colonial sites (two to eight centuries BP) are abundant, the period between 1600 and 1000 BP is characterized by a sharp decrease in human settlements, with a population crash between 1300 and 1000 BP over a large part of Central Africa. It is only in the eleventh century that new populations of metallurgists settled into the forest block. In this paper, we analyse the spatial and temporal distribution of 328 archaeological sites that have been reliably radiocarbon dated. The results allow us to piece together changes in the relationships between human populations and the environments in which they lived. On this basis, we discuss interactions between humans, climate and vegetation during the past five millennia and the implications of the absence of people from the landscape over three centuries. We go on to discuss modern vegetation patterns and African forest conservation in the light of these events.Peer reviewe

Carbon sources of Antarctic nematodes as revealed by natural carbon isotope ratios and a pulse-chase experiment

δ13C of nematode communities in 27 sites was analyzed, spanning a large depth range (from 130 to 2,021 m) in five Antarctic regions, and compared to isotopic signatures of sediment organic matter. Sediment organic matter δ13C ranged from −24.4 to −21.9‰ without significant differences between regions, substrate types or depths. Nematode δ13C showed a larger range, from −34.6 to −19.3‰, and was more depleted than sediment organic matter typically by 1‰ and by up to 3‰ in silty substrata. These, and the isotopically heavy meiofauna at some stations, suggest substantial selectivity of some meiofauna for specific components of the sedimenting plankton. However, 13C-depletion in lipids and a potential contribution of chemoautotrophic carbon in the diet of the abundant genus Sabatieria may confound this interpretation. Carbon sources for Antarctic nematodes were also explored by means of an experiment in which the fate of a fresh pulse of labile carbon to the benthos was followed. This organic carbon was remineralized at a rate (11–20 mg C m−2 day−1) comparable to mineralization rates in continental slope sediments. There was no lag between sedimentation and mineralization; uptake by nematodes, however, did show such a lag. Nematodes contributed negligibly to benthic carbon mineralization

Reply To Kenneth B. Yatai, Mark J. Dunning, Dennis Wang. Consensus Genomic Subtypes of Muscle-invasive Bladder Cancer: A Step in the Right Direction but Still a Long Way To Go. Eur Urol 2020;77:434–5

In our study the Bladder Cancer Molecular Taxonomy Group collaborated to extend a first consensus report, addressing the need for a consensus molecular classification for muscle-invasive bladder cancer (MIBC) that would support basic research and clinical trials. We provide such a consensus classification and offer a single-sample classifier (http://cit.ligue-cancer.net:3838/apps/consensusMIBC_web)