Chloride and Organic Chlorine in Soil

Chloride is ubiquitous in soil, but the past years of research have revealed that organic matter also contains chlorine, in amounts similar to that of phosphorus. Hence, one of the major constituents of soil organic matter has previously been overlooked, and still very little is known about the turnover of organic chlorine in soil. In spite of the obvious connection between chloride and organic chlorine, organic chlorine rarely is considered when the biogeochemical cycling of chloride is in focus, and chloride rarely is taken into account when the occurrence and formation of natural organic chlorine compounds are in focus. The aim of the paper is to review ten years of research concerning the biogeochemical cycling of organic chlorine in soil, and to tie the biogeochemical cycling of organic chlorine to that of chloride.     

Retrofit of non-seismically designed beam-column joints by post-tensioned superelastic shape memory alloy bars

A series of tests on three full-scale substandard exterior beam-column joints were performed to investigate the efficiency of the proposed retrofit configuration, which is the use of externally applied post-tensioned shape memory alloy (SMA) bars. A major group of structural deficiencies resulting from lack of shear reinforcement in the joint, use of low strength concrete and plain round bars were taken into account in the construction of test specimens. While the reference specimen represents the as-built subassembly, the other two were retrofitted by the post-tensioned SMA and steel bars to compare the contribution of superelastic and conventional material on the response. The specimens were exposed to quasi-static cyclic loading up to 8% drift ratio to simulate an intensive level of seismic hazard. The reference specimen underwent a brittle shear failure as excessive cracks mostly concentrated in the joint panel while there was almost no damage in the rest of the RC components. A joint failure with enhanced response quantities was observed in the specimen retrofitted by post-tensioned steel bars. The specimen incorporating the retrofit solution via post-tensioned SMA bars was capable of performing an adequate performance and promoting minimization of the damage in the joint panel, which results in more ductile behavior. The hysteretic response of the SMA retrofitted specimen was validated with a refined numerical model in ATENA Science software. Experimentally observed response was also verified by an analytical model based on fracture mechanics considering the nonlinear behavior of plain concrete under tension. Due to inherent uncertainties in material constitutive laws, the analytical model was evolved to a stochastic level to propose a more advanced model for estimating the capacity of the reference and retrofitted joint. It is found that the experimental results were within the prominent range of Probability Density Functions (i.e. mean ± 1 SD) of the estimated joint tensile stress especially for the shear damaged specimens.     

Daily pan evaporation modelling using multi‐layer perceptrons and radial basis neural networks

This paper reports on investigations of the abilities of three different artificial neural network (ANN) techniques, multi‐layer perceptrons (MLP), radial basis neural networks (RBNN) and generalized regression neural networks (GRNN) to estimate daily pan evaporation. Different MLP models comprising various combinations of daily climatic variables, that is, air temperature, solar radiation, wind speed, pressure and humidity were developed to evaluate the effect of each of these variables on pan evaporation. The MLP estimates are compared with those of the RBNN and GRNN techniques. The Stephens‐Stewart (SS) method is also considered for the comparison. The performances of the models are evaluated using root mean square errors (RMSE), mean absolute error (MAE) and determination coefficient (R²) statistics. Based on the comparisons, it was found that the MLP and RBNN computing techniques could be employed successfully to model the evaporation process using the available climatic data. The GRNN was found to perform better than the SS method. Copyright © 2008 John Wiley & Sons, Ltd.     

Studies on the effect of burden width on blast-induced vibration in open-pit mines

This study concerns the correlation between burden and blast-induced vibrations in open-pit mines. For this purpose, two different mines were studied. In these mines, the vibrations caused by explosions at burdens having widths ranging from 3 to 14 m were measured from various distances. From the results, it was found for these cases that burden width has a significant impact on vibrations. Consequently, it was proven that vibrations decrease as burden increases.     

Remark on rotational motions in flares and prominences

From material secured with the McMath Solar Telescope of the Kitt Peak National Observatory rotational (orbital) motion has been found in a prominence ejected from a rotating flare. A period of rotation of 32 min has been derived from the study of a periodic asymmetry of the AL i 3961 absorption line.Presented at the Physics of Prominences-colloquium at Anacapri, September 29, 1971.     

Selective diffraction with possible application to solar research

The writer describes diffraction phenomena in transmission gratings made as strips of alternating color. He discusses diffraction in slits formed in semitransparent material including liquid or gaseous layers and particularly when line- and band-absorption is present. He suggests that atmospheric seeing should be influenced by selective diffraction in telluric lines. He also discusses possible seeing effects in the solar atmosphere and prominences and hints at the possibility that irregular or semiregular selective diffraction may appear in the deep layers of sunspots possibly contributing to the scattering of light.     

Social Cohesion; Is it sufficient? Migrant communities in two disadvantaged neighborhoods in Istanbul

Planners assume that old neighbourhoods have an atmosphere in which social relations can easily flourish. They also regard the strong social ties within a neighborhood as the guarantee for the success of housing rehabilitation. This article argues that existence of social cohesion in a neighbourhood is not necessarily an advantage in a process of modernisation and rehabilitation. In some cases the community may constitute a closed `island' especially in places where communities have historically inherited an hierarchical character. The article is based on a recent research project dealing with urban communities in inner city areas of Istanbul, especially those containing migrant populations which seemingly have strong community ties. The historical background of the community from the Ottoman period is examined in the first part of the article. The roots of the community as a territorial administrative unit (mahalle) and its modification in contemporary migrant communities are analysed. The second part of the article presents the results of two case studies. One of the case studies is a social housing district where the migrant community is mixed and social relations with the rest of the city are relatively well developed. The other case study area is an historical district where strong social ties create an introverted character of the community in spite of its central location. The result of the study reveals that urban `communities' in a city like Istanbul have both negative and positive aspects. Primarily it is important to assess and understand the degree of `opennes' of the community to the outer world. In any action to be taken planners should look not only inside the community, but also at its 'outer' relations.     

Late Pleistocene–Holocene evolution of the southern Marmara shelf and sub-basins: middle strand of the North Anatolian fault,southern Marmara Sea,Turkey

Although there are many research studies on the northern and southern branches of the North Anatolian fault, cutting through the deep basins of the Sea of Marmara in the north and creating a series of pull-apart basins on the southern mainland, little data is available about the geometrical and kinematical characteristics of the middle strand of the North Anatolian fault. The first detailed geometry of the middle strand of the North Anatolian fault along the southern Marmara shelf, including the Gemlik and Band?rma Bay, will be given in this study, by a combined interpretation of different seismic data sets. The characteristic features of its segments and their importance on the paleogeographic evolution of the southern shelf sub-basins were defined. The longest one of these faults, the Armutlu-Band?rma segment, is a 75-km long dextral strike-slip fault which connects the W–E trending Gençali segment in the east and NE–SW trending Kap?da?-Edincik segment in the west. In this context, the Gemlik Bay opened as a pull-apart basin under the control of the middle strand whilst a new fault segment developed during the late Pleistocene, cutting through the eastern rim of the bay. In this region, a delta front forming the paleoshoreline of the Gemlik paleolake was cut and shifted approximately 60 ± 5 m by the new segment. The same offset on this fault was also measured on a natural scarp of acoustic basement to the west and integrated with this paleoshoreline forming the slightly descending topset–foreset reflections of the delta front. Therefore the new segment is believed to be active at least for the last 30,000 years. The annual lateral slip rate representing this period of time will be 2 mm, which is quite consistent with modern GPS measurements. Towards the west, the Band?rma Bay is a rectangular transpressional basin whilst the Erdek Bay is a passive basin under the control of NW–SE trending faults. When the water level of the paleo-Marmara lake dropped down to ?90 m, the water levels of the suspended paleolakes of Band?rma and Gemlik on the southern shelf were ?50.3 (?3.3 Global Isostatic Adjustment—GIA) and ?60.5 (?3.3 GIA) m below the present mean sea level, respectively. As of today a similar example can be seen between the Sea of Marmara and the shallow freshwater lakes of Manyas and Uluabat. Similarly, the paleolakes of Gemlik and Bandirma were affected by the water level fluctuations at different time periods, even though both lakes were isolated from the Sea of Marmara during the glacial periods.