62 research outputs found
Formation of giant polymer vesicles by simple double emulsification using block copolymers as the sole surfactant dagger
De visserskaai te Oostende (prov. West-Vlaanderen): archeologie van een in de 17de eeuw zwaar geteisterde stad
The Institute for the Archaeological Heritage of the Flemish Community (IAP) has, in close collaboration with the town of Ostend, carried out archaeological excavations during the construction works of the car park below the Visserskaai at Ostend from September 1998 till February 1999. This archaeological work mainly produced information on the eastern ramparts of Ostend and their evolution from the 16th century onwards together with information on the material culture of the inhabitants of Ostend during this same period. The town of Ostend had no defences until late in the 16th century as initial construction work for the defences only started in 1572 when the town came into northern hands. In the beginning of the 17th century Ostend managed to withstand successfully, with its newly built ramparts, for three years an overwhelming Spanish army siege. This was only possible thanks to the fact that the Spaniards never managed to seal of Ostend completely from the sea. As a result, victuals and soldiers arrived continuously at Ostend during the siege. It was only after the arrival of Spinola in the besieging camp, at the end of 1603, that Ostend was gradually forced to surrender. At the bottom of the excavated car park trench, some 4 m below the actual street level, wooden structures of the earthen ramparts were preserved (figs. 4-5). The presence of these con- firms historical data about the use of wood to strengthen the earthen ramparts. The excavations however documented mainly features from 2 bastions, the Peckels bastion and the Spanish bastion (fig. 2-3). Human burials and a gunpowder-magazine (figs. 7, 8, 10, 12) were uncovered in the Peckels bastion and human burials and an open-air rainwater reservoir were detected in the Spanish bastion. The human burials are studied elsewhere in this volume together with other post-medieval burials from Ostend recently discovered outside regular cemeteries. Archaeological material found in connection with the gunpowder-magazine in the Peckelf bastion dates from the 2nd half of the 16th /1st half of the 17th century (figs. 6,9,13-15) and suggests that the construction of this gunpowder-magazine? has to be situated somewhere in the middle of the 17th century, in other words in the period when the town defences of Ostend were adapted to new standards after the above- mentioned siege. A typical object related to the siege is a funnel-shaped gunpowder-flask in a copper-alloy (fig. 6). The inner wall of the gunpowder-magazine was erected on a framework of horizontal wooden beams, which were themselves resting on vertically placed and sharpened beams, mainly in oak (fig. 8). A dendrochronological analysis of the vertically placed beams produced a terminus post quem, which is far too early to be of any help in the discussion on the gunpowder-magazine. The technical differences between the inner and outer wall of the gunpowder-magazine suggest at least 2 phases for this building. The above-mentioned ceramics consist of redwares, Rhenish stone- wares a.o. Raeren, maiolicas, Weser slipwares, olive jars from Seville and some whitewares with green or yellow glaze. The archaeological material from the open- air rainwater reservoir in the Spanish bastion dates from the 2nd half of the 17th/1st half of the 19th century but mainly from the 18th century (figs. 16-32). The collection of ceramics from this context is largely dominated by tablewares. Among these stonewares are nearly missing and replaced by faience, china and industrial white- wares (pearl and cream wares). Maiolica has been nearly completely replaced by faience. Maiolicas remain in fact only important as wall-tiles. The collection contains some olive jars from Seville, a bowl from Dèsvres and a few products from Beauvais. The collection of china mainly consists of cups and small dishes in blue and white china. The china has been brought to Ostend in great quantities in the 18th century, first by the Ostend Company and later by mariners from Ostend in Foreign Service, mainly as ship's ballast. Besides ceramics this context also produced several finds in leather, glass, stone and metal. The leather finds mainly consist of shoes. The glass collection is largely dominated by cylindrical and globular bottles of which one was still intact including its cork (fig. 26: 1). Metal is represented by 22 cast iron cannon balls (fig. 28) and by a standard measure for bottles from an unidentified town inspector of measures and weights of Ostend with GS initials (fig. 27: 8). Small quantities of animal remains were found dispersed over many contexts within the site's stratigraphy. Only three of them are meaningful: a deposit found under the floor of the gunpowder-magazine (table 1: context A), an assemblage excavated in leveling layers within the Peckels bastion (table 1: context B), and material found in the water reservoir in the Spanish bastion (table 1: context C). All connections consisted of larger material; sieved samples did not yield meaningful numbers of smaller animal remains. Context A dates from the second half of the 16th to the first half of the 17th century and consists of consumption refuse: marine molluscs, marine fish bones, bird bone and the remains of cattle, sheep and pig. Context B is contemporaneous to context A and also represents consumption refuse with a similar composition. Remarkable are only a series of vertebrae of a large specimen of ling, a fish that must have been caught in northern waters, and a number of skeletal elements of a gurnard species. Context C has a younger date (second half of the 17th century to the first half of the 19th century) and has a mixed origin in terms of the taphonomy of the animal remains. Not only consumption refuse is present but also parts of the skeletons of at least four dogs and a horse. It is possible that all three contexts represent secondary refuse; in any case their provenance remains unknown. The material certainly has limited value for the interpretation of former consumption patterns. A feature of special interest is the presence of a few cowrie shells. Several aspects of the material culture reflect the maritime character of the town: the presence of several imports such as olive jars from Seville and specific objects as a token in lead (fig. 13: 16) probably used by skippers for the payment of fees and/or tolls. The presence of an important percentage of china and of some cowrie shells is probably related to the activities of the Ostend Company in the l8th century. The pottery discovered from both contexts (2nd half 16th century/ 1 st half 17th century and 2nd half 17th century/ 1st half 19th century) follows the general trends described for post-medieval Flanders
Scoping prediction of re-radiated ground-borne noise and vibration near high speed rail lines with variable soils
This paper outlines a vibration prediction tool, ScopeRail, capable of predicting in-door noise and vibration, within structures in close proximity to high speed railway lines. The tool is designed to rapidly predict vibration levels over large track distances, while using historical soil information to increase accuracy. Model results are compared to an alternative, commonly used, scoping model and it is found that ScopeRail offers higher accuracy predictions. This increased accuracy can potentially reduce the cost of vibration environmental impact assessments for new high speed rail lines.
To develop the tool, a three-dimensional finite element model is first outlined capable of simulating vibration generation and propagation from high speed rail lines. A vast array of model permutations are computed to assess the effect of each input parameter on absolute ground vibration levels. These relations are analysed using a machine learning approach, resulting in a model that can instantly predict ground vibration levels in the presence of different train speeds and soil profiles. Then a collection of empirical factors are coupled with the model to allow for the prediction of structural vibration and in-door noise in buildings located near high speed lines. Additional factors are also used to enable the prediction of vibrations in the presence of abatement measures (e.g. ballast mats and floating slab tracks) and additional excitation mechanisms (e.g. wheelflats and switches/crossings)
Regional Patterns of Late Medieval and Early Modern European Building Activity Revealed by Felling Dates
Although variations in building activity are a useful indicator of societal well-being and demographic development, historical datasets for larger regions and longer periods are still rare. Here, we present 54,045 annually precise dendrochronological felling dates from historical construction timber from across most of Europe between 1250 and 1699 CE to infer variations in building activity. We use geostatistical techniques to compare spatiotemporal dynamics in past European building activity against independent demographic, economic, social and climatic data. We show that the felling dates capture major geographical patterns of demographic trends, especially in regions with dense data coverage. A particularly strong negative association is found between grain prices and the number of felling dates. In addition, a significant positive association is found between the number of felling dates and mining activity. These strong associations, with well-known macro-economic indicators from pre-industrial Europe, corroborate the use of felling dates as an independent source for exploring large-scale fluctuations of societal well-being and demographic development. Three prominent examples are the building boom in the Hanseatic League region of northeastern Germany during the 13th century, the onset of the Late Medieval Crisis in much of Europec. 1300, and the cessation of building activity in large parts of central Europe during armed conflicts such as the Thirty Years’ War (1618–1648 CE). Despite new insights gained from our European-wide felling date inventory, further studies are needed to investigate changes in construction activity of high versus low status buildings, and of urban versus rural buildings, and to compare those results with a variety of historical documentary sources and natural proxy archives.</jats:p
<i>De novo</i> design of a four-fold symmetric TIM-barrel protein with atomic-level accuracy
Despite efforts for over 25 years, de novo protein design has not succeeded in achieving the TIM-barrel fold. Here we describe the computational design of 4-fold symmetrical (β/α)(8)-barrels guided by geometrical and chemical principles. Experimental characterization of 33 designs revealed the importance of sidechain-backbone hydrogen bonding for defining the strand register between repeat units. The X-ray crystal structure of a designed thermostable 184-residue protein is nearly identical with the designed TIM-barrel model. PSI-BLAST searches do not identify sequence similarities to known TIM-barrel proteins, and sensitive profile-profile searches indicate that the design sequence is distant from other naturally occurring TIM-barrel superfamilies, suggesting that Nature has only sampled a subset of the sequence space available to the TIM-barrel fold. The ability to de novo design TIM-barrels opens new possibilities for custom-made enzymes
Knockdown of the thyroid hormone transporter MCT8 in chicken retinal precursor cells hampers early retinal development and results in a shift towards more UV/blue cones at the expense of green/red cones
Thyroid hormones (THs) play a crucial role in coordinating brain development in vertebrates. They fine-tune processes like cell proliferation, migration, and differentiation mainly by regulating the transcriptional activity of many essential genes. Regulators of TH availability thereby define the cellular concentration of the bioactive 3,5,3'-triiodothyronine, which binds to nuclear TH receptors. One important regulator, the monocarboxylate transporter 8 (MCT8), facilitates cellular TH uptake and is known to be necessary for correct brain development, but data on its potential role during retinal development is lacking. The retinal cyto-architecture has been conserved throughout vertebrate evolution, and we used the chicken embryo to study the need for MCT8 during retinal development. Its external development allows easy manipulation, and MCT8 is abundantly expressed in the retina from early stages onwards. We induced MCT8 knockdown by electroporating a pRFP-MCT8-RNAi vector into the retinal precursor cells (RPCs) at embryonic day 4 (E4), and studied the consequences for early (E6) and late (E18) retinal development. The empty pRFP-RNAi vector was used as a control. RPC proliferation was reduced at E6. This resulted in cellular hypoplasia and a thinner retina at E18 where mainly photoreceptors and horizontal cells were lost, the two predominant cell types that are born around the stage of electroporation. At E6, differentiation into retinal ganglion cells and amacrine cells was delayed. However, since the proportion of a given cell type within the transfected cell population at E18 was similar in knockdown and controls, the partial loss of some cell types was most-likely due to reduced RPC proliferation and not impaired cell differentiation. Photoreceptors displayed delayed migration at first, but had successfully reached the outer nuclear layer at E18. However, they increasingly differentiated into short wavelength-sensitive cones at the expense of medium/long wavelength-sensitive cones, while the proportion of rods was unaltered. Improperly formed sublaminae in the inner plexiform layer additionally suggested defects in synaptogenesis. Altogether, our data echoes effects of hypothyroidism and the loss of some other regulators of TH availability in the developing zebrafish and rodent retina. Therefore, the expression of MCT8 in RPCs is crucial for adequate TH uptake during cell type-specific events in retinal development.status: publishe
THE DIAZONIUM GROUP - AN ELECTRON-ACCEPTOR FOR LARGE MOLECULAR HYPERPOLARIZABILITIES
The diazonium compounds 4-dialkylamino-4'-phenylazobenzenediazonium tetrafluoroborate are synthesised and their molecular hyperpolarizabilities (beta) measured with the hyper-Rayleigh scattering technique; the diazonium compounds show much larger beta values than the corresponding nitro compounds.open1125sciescopu
Large molecular quadratic hyperpolarizabilites in donor/acceptor-substituted trans-tetraamineruthenium(II) complexes
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