The Byzantine Cisterns of Constantinople

The most unusual aspect of Byzantine Constantinople's water system was the large number of cisterns throughout the city. This research integrates the two most recent in-depth studies of the cisterns to determine that there have been at least 211 cisterns attributed to the Byzantine city. The distribution of the cisterns indicates that the size and number of cisterns constructed reduced over time, with more and larger cisterns developed prior to the seventh century. Cisterns are concentrated in the older area of the City and sparser on the periphery, but with later ones more common in the peripheral areas, suggesting that water provision was extended over time, and although the majority of cisterns are small, most storage volume is concentrated in the three largest open-air cisterns. The extended, detailed list produced will allow more in-depth investigations to proceed. Analysis of the distribution of cisterns across the City creates a framework for understanding the development and functioning of Byzantine Constantinople's complex water supply system

A GIS-based assessment of the Byzantine water supply system of Constantinople

Despite the extensive archaeological surveys carried out in the last decades, little attention has been paid to one of the longest water supply systems of ancient times - the Byzantine water infrastructure which fed Constantinople from the mid-late fourth century AD. This work uses modern satellite terrain data and Global Positioning System (GPS) data to assess this system and provide an improved description of its route, total length and gradient profile. 44 validated GPS Control Points were correlated with ASTER GDEM V2 digital satellite data and archaeological information in a Geographic Information System (GIS) environment. We concluded that the total length of the water supply system was 426 km, and possibly even 565 km if the fifth-century aqueduct continued in parallel all the way to Constantinople rather than merging with the fourth-century aqueduct. The gradient of the channels varied across their length, being steepest near the spring sources, with gradient mostly in the region of 5 m/km, and flattest at around 0.4 m/km in the most downstream section nearest the City. This reconstruction of the gradient profile provides valuable insight into the physical characteristics of the system, allowing future study of its hydraulic function

The climate benefit of carbon sequestration

Ecosystems play a fundamental role in climate change mitigation by photosynthetically fixing carbon from the atmosphere and storing it for a period of time in organic matter. Although climate impacts of carbon emissions by sources can be quantified by global warming potentials, the appropriate formal metrics to assess climate benefits of carbon removals by sinks are unclear. We introduce here the climate benefit of sequestration (CBS), a metric that quantifies the radiative effect of fixing carbon dioxide from the atmosphere and retaining it for a period of time in an ecosystem before releasing it back as the result of respiratory processes and disturbances. In order to quantify CBS, we present a formal definition of carbon sequestration (CS) as the integral of an amount of carbon removed from the atmosphere stored over the time horizon it remains within an ecosystem. Both metrics incorporate the separate effects of (i) inputs (amount of atmospheric carbon removal) and (ii) transit time (time of carbon retention) on carbon sinks, which can vary largely for different ecosystems or forms of management. These metrics can be useful for comparing the climate impacts of carbon removals by different sinks over specific time horizons, to assess the climate impacts of ecosystem management, and to obtain direct quantifications of climate impacts as the net effect of carbon emissions by sources versus removals by sinks.Peer reviewe

Engineering exploration of the water supply system of Constantinople

Before this research study began, relatively little was understood of the water supply in Constantinople, particularly within the walls of the city. Archaeological work had focused on collecting details of 160 cisterns and a small number of channels and pipes were incidental finds in other excavations. Although no-one had considered the water supply in Constantinople as a whole, the evidence seemed to indicate a sophisticated water management system. With the available data fragmented, and the potential for more evidence limited to serendipitous finds associated with construction work, the only way to move the understanding of the water supply forward is to take a radically different perspective: civil engineers are well placed to envisage the water supply as a working system and make use of their modern design skills and tools to fill in the gaps between the fragmented data. This reimagining of the water supply system was driven by a key piece of knowledge: the water supply worked, and worked for many centuries. That fact, combined with the fragments of physical and literary evidence, the largely unchanged landscape and the fundamental physical laws governing gravity-fed water systems, are enough to start filling in the information to create a complete system. The core work in reimagining the water supply system has been developing an understanding of the physical infrastructure of the distribution system. Although the two most recent and comprehensive studies appeared to agree that there were about 159 cisterns in the city, close examination of the available data showed that there were actually 209 with the possibility of more. An evaluation of the aqueduct routes in previous studies highlighted inconsistencies with newly available evidence: alternative routes were designed that tied together the available evidence, providing a consistently downhill route, shorter and more straightforward to construct. Having established the number and spread of cisterns and the locations of the aqueducts, it was possible to create a network delivering water from the aqueduct channels to the cisterns for collection by the public. Consideration has also been given to what occurs at either end of this physical infrastructure. At the upstream end, quantifying and characterising the water source defines the water available to distribute and helps to indicate the purpose of the cisterns. At the downstream end, developing even a basic model of water consumption has enabled the distribution network to move from a static artefact to a system with a quantifiable purpose. The combination of the physical infrastructure, inflow data and demand assumptions in an agent-based model demonstrate that the decisions and assumption made within each element work together and allow a fourth element, management, to be considered. The agent-based model of the water supply enables consideration of a dynamic system and the exploration of a number of “what if?” scenarios. This exploration concludes that the cistern-based distribution system probably developed because of fluctuations in inflow. It may have been possible for the city to use a merged arrangement on the Aqueduct of Valens inflow, but the burden of pro-active management required to make it successful suggests that a parallel arrangement is more likely. There was likely to be an interconnection between the two main aqueducts, which would have enabled the use of water stored in the largest open-air cisterns

Purification and In Vitro Growth of Human Epidermal Basal Keratinocytes Using a Monoclonal Antibody

We have made a new monoclonal antibody, EL-2, and used it with an immunorosetting procedure combined with Ficoll-Hypaque gradient centrifugation to purify and culture basal keratinocytes. Immunofluorescence of cell suspensions and immunoperoxidase staining of tissue sections demonstrate that EL-2 reacts with malignant cell lines, activated lymphocytes and monocytes, and basal keratinocytes. Sequential immunoprecipitation studies demonstrate that monoclonal antibodies EL-2 and 4F2 detect the same membrane protein. However, we have extended previous studies by making the new observation that both EL-2 and 4F2 react with cultured melanocytes. Basal keratinocytes were purified from single-cell epidermal suspensions by incubation with EL-2 followed by rosetting with rabbit antimouse IgG antibodies covalently linked to bovine red blood cells. Rosetting (basal) keratinocytes were separated from EL-2 negative cells by Ficoll gradient centrifugation. We obtained basal keratinocyte populations of >90% purity as assessed by reactivity with EL-2 and another basal keratinocyte-specific monoclonal antibody, HCl. Langerhans cell, fibroblast, and melanocyte contamination was negligible. Cultures of basal keratinocytes were enriched in EL-2-reactive cells throughout the entire 19 days of culture studied. EL-2 is being used to characterize disorders of keratinocyte proliferation; EL-2 reacted with both squamous and basal cell carcinomas. EL-2 stained only the basal layer of lesional skin from patients with psoriasis, pityriasis rubra pilaris, and Darier's disease. Purification of basal keratinocytes will be important in biochemical and functional studies of normal skin and in establishing long-term keratinocyte lines from normal cells

Corrigendum: Collective search by ants in microgravity

The problem of collective search is a tradeoff between searching thoroughly and covering as much area as possible. This tradeoff depends on the density of searchers. Solutions to the problem of collective search are currently of much interest in robotics and in the study of distributed algorithms, for example to design ways that without central control robots can use local information to perform search and rescue operations. Ant colonies operate without central control. Because they can perceive only local, mostly chemical and tactile cues, they must search collectively to find resources and to monitor the colony's environment. Examining how ants in diverse environments solve the problem of collective search can elucidate how evolution has led to diverse forms of collective behavior. An experiment on the International Space Station in January 2014 examined how ants (Tetramorium caespitum) perform collective search in microgravity. In the ISS experiment, the ants explored a small arena in which a barrier was lowered to increase the area and thus lower ant density. In microgravity, relative to ground controls, ants explored the area less thoroughly and took more convoluted paths. It appears that the difficulty of holding on to the surface interfered with the ants’ ability to search collectively. Ants frequently lost contact with the surface, but showed a remarkable ability to regain contact with the surface

Vasopressin excites interneurons to suppress hippocampal network activity across a broad span of brain maturity at birth

During birth in mammals, a pronounced surge of fetal peripheral stress hormones takes place to promote survival in the transition to the extrauterine environment. However, it is not known whether the hormonal signaling involves central pathways with direct protective effects on the perinatal brain. Here, we show that arginine vasopressin specifically activates interneurons to suppress spontaneous network events in the perinatal hippocampus. Experiments done on the altricial rat and precocial guinea pig neonate demonstrated that the effect of vasopressin is not dependent on the level of maturation (depolarizing vs. hyperpolarizing) of postsynaptic GABA(A) receptor actions. Thus, the fetal mammalian brain is equipped with an evolutionarily conserved mechanism well-suited to suppress energetically expensive correlated network events under conditions of reduced oxygen supply at birth.Peer reviewe

Raman spectroscopy and advanced mathematical modelling in the discrimination of human thyroid cell lines

Raman spectroscopy could offer non-invasive, rapid and an objective nature to cancer diagnostics. However, much work in this field has focused on resolving differences between cancerous and non-cancerous tissues, and lacks the reproducibility and interpretation to be put into clinical practice. Much work is needed on basic cellular differences between malignancy and normal. This would allow the establishment of a clinically relevant cellular based model to translate to tissue classification. Raman spectroscopy provides a very detailed biochemical analysis of the target material and to 'unlock' this potential requires sophisticated mathematical modelling such as neural networks as an adjunct to data interpretation. Commercially obtained cancerous and non-cancerous cells, cultured in the laboratory were used in Raman spectral measurements. Data trends were visualised through PCA and then subjected to neural network analysis based on self-organising maps; consisting of m maps, where m is the number of classes to be recognised. Each map approximates the statistical distribution of a given class. The neural network analysis provided a 95% accuracy for identification of the cancerous cell line and 92% accuracy for normal cell line. In this preliminay study we have demonstrated th ability to distinguish between "normal" and cancerous commercial cell lines. This encourages future work to establish the reasons underpinning these spectral differences and to move forward to more complex systems involving tissues. We have also shown that the use of sophisticated mathematical modelling allows a high degree of discrimination of 'raw' spectral data