Studies supporting an upper-atmosphere chemical release program. Part I - Experimental studies on chemiluminescence. Part II - A model of releases leading to upper-atmospheric chemi-ion formation Final report, May 1965 - May 1966

Chemiluminescence of chemical compounds released in upper atmosphere and model of releases leading to upper atmospheric chemi-ionizatio

Possible coupling between climatically induced lake level change, volcanic eruptions and seismotectonic activation in the Rukwa-Rungwe-Nyasa rift, SW Tanzania

The Rukwa rift basin is presently a closed hydrogeological depression containing a shallow lake (max 20 me deep) with its surface at an altitude around 810 m above sea level. Lacustrine terraces and paleo-shorelines are known up to 980 m above sea level, an altitude at which it reach the overflow sill towards Lake Tanganyika. Both Lakes Tanganyika and Nyasa (Malawi) are presently overflowing, but as their lake level fluctuates, they have been disconnected from their outlet in the recent past. High resolution seismic profiling in both Lakes Rukwa and Malawi has show the presence of active fault systems underneath the lake floor. Some of these fault systems appear to have had a cyclic activity, with alternating periods of high tectonic activity/sedimentation and periods of tectonic quiescence. The accommodation zone between Lake Rukwa and Nyasa is occupied by the Rungwe volcanic Province, with the Ngozi, Rungwe and Kiejo volcanoes presenting signs of recent volcanic activity. The Rungwe Province is cross-cut by several directions of faults, which clearly control the location of the volcanic vents.In our work, we reviewed the available data on recent (Late Pleistocene – Holocene) volcanic eruptions, in the Rungwe area itself, in the drill cores from the surrounding lakes and from aerial observations up to 300 km away from the Rungwe Province. We performed morphotectonic and paleoseismic investigations of the Kanda fault, a major normal fault between lakes Rukwa and Tanganyika. We investigated lacustrine deposits of the Rukwa basin corresponding to the two last cycles of high lake level. The chronological framework was established using 30 new radiocarbon dating and the most prominent volcanic tephra layers were used as a reference in the correlations. The results are still preliminary, but a good correlation already appear between climatically induced lake level change (in Lake Rukwa), seismo-tectonic activation of the regional fault network (underneath Lake Rukwa and the Kanda fault between Lakes Rukwa and Tanganyika) and the timing of the recent strong volcanic eruptions in the Rungwe Volcanic Province since the last 40.000 years. This relation is explained taking into account that Lake Rukwa is very sensitive to climate change as it occupies a flat depression and its overflow outlet is 180 m above its present-day level. Its lake level rises rapidly when the climate becomes more humid as it was the case during the Last Glacial Maximum and during the Younger Dryas event. Increase in lake level means increasing of the load in the basin and perturbation of the ambient tectonic stresses. In most of the Rukwa rift, the tectonic stress is of extensional (normal faulting) regime, with the maximum principal stress axis (sigma 1) subvertical. In these conditions, increasing the vertical load will increase the shear stress on the existing normal faults, triggering (seismogenic) normal faulting deformation. As the architecture of the active volcanoes in the Rungwe Province is tectonically controlled, activation of the faults, together with a greater pressure of water in the tectonic discontinuities are likely to trigger large volcanic eruptions, strongly explosive

Lessons from Love-Locks: The archaeology of a contemporary assemblage

This document is the Accepted Manuscript version. The final, definitive version of this paper has been published in Journal of Material Culture, November 2017, published by SAGE Publishing, All rights reserved.Loss of context is a challenge, if not the bane, of the ritual archaeologist’s craft. Those who research ritual frequently encounter difficulties in the interpretation of its often tantalisingly incomplete material record. Careful analysis of material remains may afford us glimpses into past ritual activity, but our often vast chronological separation from the ritual practitioners themselves prevent us from seeing the whole picture. The archaeologist engaging with structured deposits, for instance, is often forced to study ritual assemblages post-accumulation. Many nuances of its formation, therefore, may be lost in interpretation. This paper considers what insights an archaeologist could gain into the place, people, pace, and purpose of deposition by recording an accumulation of structured deposits during its formation, rather than after. To answer this, the paper will focus on a contemporary depositional practice: the love-lock. This custom involves the inscribing of names/initials onto a padlock, its attachment to a bridge or other public structure, and the deposition of the corresponding key into the water below; a ritual often enacted by a couple as a statement of their romantic commitment. Drawing on empirical data from a three-year diachronic site-specific investigation into a love-lock bridge in Manchester, UK, the author demonstrates the value of contemporary archaeology in engaging with the often enigmatic material culture of ritual accumulations.Peer reviewe

Melanoma, the role of basic Fibroblast Growth Factor in the aggressive behaviour and chemotherapy response

Boven, E. [Promotor]Duyndam, M.C.A. [Copromotor

Surface-wave imaging of the weakly-extended Malawi Rift from ambient-noise and teleseismic Rayleigh waves from onshore and lake-bottom seismometers

Located at the southernmost sector of the Western Branch of the East African Rift System, the Malawi Rift exemplifies an active, magma-poor, weakly extended continental rift. To investigate the controls on rifting, we image crustal and uppermost mantle structure beneath the region using ambient-noise and teleseismic Rayleigh-wave phase velocities between 9 and 100 s period. Our study includes six lake-bottom seismometers located in Lake Malawi (Nyasa), the first time seismometers have been deployed in any of the African rift lakes. Noise-levels in the lake are lower than that of shallow oceanic environments and allow successful application of compliance corrections and instrument orientation determination. Resulting phase-velocity maps reveal slow velocities primarily confined to Lake Malawi at short periods (T 25 s) a prominent low-velocity anomaly exists beneath the Rungwe Volcanic Province at the northern terminus of the rift basin. Estimates of phase-velocity sensitivity indicates these low velocities occur within the lithospheric mantle and potentially uppermost asthenosphere, suggesting that mantle processes may control the association of volcanic centers and the localization of magmatism. Beneath the main portion of the Malawi Rift, a modest reduction in velocity is also observed at periods sensitive to the crust and upper mantle, but these velocities are much higher than those observed beneath Rungwe

The Lady under the hill: an osteobiography of a Middle Bronze Age cremated female from Ermelose Heide (Ermelo, prov. Gelderland, the Netherlands)

Cremated human remains are an important source of information on the life and well-being of past individuals, but due to their nature (i.e. burnt, fragmented) often form a challenge to analyse. Generally, cremation cemeteries are considered on a population level, but by creating life narratives, the socioculturalroles that certain individuals had in past societies can be reconstructed. The burial ground of Ermelose Heide currently consists of 46 prehistoric mounds. Several mounds were excavated in the 1950s, whereby mound 14 was comprised of two "submounds", a small and a large one, after which both mounds were covered to look like one. Mound 14 contained 7 cremation graves, 4 in 14Large and 3 in 14Small. One of the cremation deposits, V41, was located separately from the rest in 14Small and was composed of the burnt remains of an older female and a foetus (~28 weeks in utero). The remains of the female were nearly complete, as opposed to the other cremation deposits in mound 14. Although it is not possible to prove that the female was the mother of the foetus, if indeed she was, she would have been visibly pregnant.In addition, her lumbar vertebrae showed lesions that could be the result of trauma, which most likely was exacerbated by the presence of an incomplete fusion of her 4th lumbar vertebra. Considering that she may have been visibly pregnant and potentially had trouble or pain while walking as a result from the spinal trauma, it is possible that she was viewed upon differently than the rest. By creating an osteobiographyfor the female with the foetus in mound 14, her life narrative highlights the divergent nature of her funerary practices, aiding in the reconstruction of her sociocultural role withing the MBA-society of Ermelose Heide.Bioarchaeolog

A Bronze Age Round Barrow Cemetery, Pit Alignments, Iron Age Burials, Iron Age Copper Working, and Later Activity at Four Crosses, Llandysilio, Powys.

Excavation undertaken at the Upper Severn valley round barrow cemetery at Four Crosses, Llandysilio between 2004 and 2006 has increased the known barrows and ring-ditches to some 26 monuments, and revealed additional burials. Based on limited dating evidence, and the data from earlier excavations, the majority of the barrows are thought to be constructed in the Bronze Age. The barrows are part of a larger linear cemetery and the landscape setting and wider significance of this linear barrow cemetery are explored within this report. Dating suggests two barrows were later, Iron Age additions. The excavation also investigated Iron Age and undated pit alignments, Middle Iron Age copper working and a small Romano-British inhumation cemetery and field systems. Much of this evidence reflects the continuing importance of the site for ritual and funerary activity

Fluidal pyroclasts reveal the intensity of peralkaline rhyolite pumice cone eruptions

This work is a contribution to the Natural Environment Research Council (NERC) funded RiftVolc project (NE/L013932/1, Rift volcanism: past, present and future) through which several of the authors are supported. In addition, Clarke was funded by a NERC doctoral training partnership grant (NE/L002558/1).Peralkaline rhyolites are medium to low viscosity, volatile-rich magmas typically associated with rift zones and extensional settings. The dynamics of peralkaline rhyolite eruptions remain elusive with no direct observations recorded, significantly hindering the assessment of hazard and risk. Here we describe uniquely-preserved, fluidal-shaped pyroclasts found within pumice cone deposits at Aluto, a peralkaline rhyolite caldera in the Main Ethiopian Rift. We use a combination of field-observations, geochemistry, X-ray computed microtomography (XCT) and thermal-modelling to investigate how these pyroclasts are formed. We find that they deform during flight and, depending on size, quench prior to deposition or continue to inflate then quench in-situ. These findings reveal important characteristics of the eruptions that gave rise to them: that despite the relatively low viscosity of these magmas, and similarities to basaltic scoria-cone deposits, moderate to intense, unstable, eruption columns are developed; meaning that such eruptions can generate extensive tephra-fall and pyroclastic density currents.Publisher PDFPeer reviewe

Neutron-based analyses of three Bronze Age metal objects: a closer look at the Buggenum, Jutphaas and Escharen artefacts

Three important Bronze Age copper-alloy artefacts from the permanent exhibition of the National Museum of Antiquity in Leiden (NL) have been studied by neutron-based methods. These artefacts are known as the Buggenum sword, the Jutphaas dirk, and the Escharen double axe. All three objects have been studied with neutron resonance capture analysis (NRCA), a non-destructive method to determine the bulk elemental compositions. The Buggenum sword is also studied with time-of-flight neutron diffraction (TOF-ND) giving additional information about crystalline properties and internal material structures, and neutron tomography (NT), showing details of the construction of this sword and voids inside the material. The composition of the Jutphaas dirk is compared with the compositions of two other dirks belonging to the group of six Plougrescant-Ommerschans (PO) ceremonial dirks. The Escharen double axe, identified as being of the Zabitz type, variant Westeregeln, is a rare object in the Low Countries. It is compared to finds from Central Europe. The results for all three objects are discussed with regards to their archaeological contexts and their relation to other finds

Eruption frequency and magnitude in a geothermally active continental rift: The Bora-Baricha-Tullu Moye volcanic complex, Main Ethiopian Rift

Many Quaternary silicic volcanoes in the Main Ethiopian Rift pose a potential risk due to the poorly known eruptive histories of the volcanoes in combination with a high population density. In this study we provide new constraints on the Late Pleistocene-Holocene eruptive history of the Bora-Baricha-Tullu Moye (BBTM) volcanic complex located in the central portion of the Main Ethiopian Rift (MER). BBTM constitutes three main silicic edifices (i.e. Bora, Baricha and Tullu Moye) and numerous smaller vents (including Oda and Werdi). Tephra deposits from these vents are several centimetres to meters in thickness in currently densely populated regions and where geothermal development is taking place. We present new field observations in addition to physical, petrographic, geochemical and geochronological data. BBTM experienced at least 27 explosive eruptions, of varying magnitude, in the last ca. 100 ky. The two oldest tephra deposits in our compiled stratigraphy are associated with large-magnitude, and possibly caldera-forming eruptions. The youngest of these (Meki) occurred at 107.7 ± 8.8 (2σ) ka, which makes it the youngest caldera-forming eruption identified in the Central MER so far. During the post-caldera stage, BBTM underwent at least 25 eruptions sourced from the Baricha (9 eruptions), Bora (3), Oda (8), Werdi (3) and Tullu Moye (2) edifices. The return period of explosive activity in BBTM is thus at least one moderate-to-large explosive eruption every 4000 yr. Well-exposed units have estimated eruption magnitudes (M) that are 4 to 5, while smaller-scale eruptions reach up to 2.5 and are exclusively preserved near the Tullu Moye vent. The tephra was dispersed up to 20 km from the volcanic complex suggesting that more than one hundred thousand people could be exposed to tephra fall and pyroclastic density current hazards from future of similar-magnitude eruptions in this area