Academic literature on the topic 'Construction Materials Performance and Processes not elsewhere classified'

The article presents current problems of irrigation canals. We list research methods while specifying the methods and work processes used. We have schematically depicted and theoretically described the necessary operations for the construction, reconstruction and repair of irrigation canals. Additionally, we have substantiated the economic losses arising from using concrete facing materials, and proposed modern facing materials designed to solve the main issues of irrigation canals. The article demonstrates the results of work on laying concrete canvas and geosynthetic materials. We have described and clearly classified the proposed facing materials and systemically listed advantages and disadvantages of modern facing materials compared to standard concrete canvas. On the basis of the study, the technological intensification of melioration was presented by reducing the construction and maintenance load on irrigation canals. We have theoretically and visibly demonstrated the efficiency of proposed materials and mathematically proven the intensification of melioration by reducing the maintenance load on irrigation canals. The findings indicate that the use of the proposed materials should increase the performance of irrigation grids, as well as reduce the maintenance load on them.

Emulsion stabilisation of base layers surfaced with chip seals often proves problematic, with chips punching into the base and early distress. This can be aggravated by the use of modified binders that restricts the evaporation of moisture from pavement layers. The introduction of new-age (nano)-modified emulsion (NME) stabilisation has the advantage that water is chemically repelled from the stabilised layer, resulting in an accelerated development of strength. A need was identified to evaluate the early-life performance of selected chip and Cape seals, together with identified modified binders on anionic NME-stabilised base layers constructed with materials traditionally classified as unsuitable, using archaic empirically derived tests. Three different chip seal surfacings with unconventional modified binders were constructed and evaluated using accelerated pavement testing (APT) with the Model Mobile Load Simulator—3rd model (MMLS3). The objectives of the experimental design and testing were to evaluate the binder performance, chip seal performance in terms of early loss of chips before chip orientation, punching of the chips into the anionic NME-stabilised base and deformation characteristics of a Cape seal that was hand-laid using an anionic NME slurry without any cement filler. It was shown that that chip seal surfacings can be used at low risk, on a base layer containing materials with fines exceeding 22%. The selection of specific modified binders can reduce risks associated with chip seal surfacings, which can impact construction limitations. The recommended use of elastomer-modified binders on newly constructed or rehabilitated layers, resulting in moisture entrapment, needs to be reconsidered.

Aim. To suggest a new method of energy-efficient traffic planning for subways. Traffic planning is understood as passenger train scheduling in compliance with all the applicable requirements and restrictions involving hourly performance in terms of the specified number of handled train pairs, efficient use of the theoretical and practical capacity of a given subway line, safety of vehicle traffic ensured by timely technical diagnostics of the rolling stock in the form of scheduled repairs and inspections in depots and/or lineside technical inspection stations, passenger comfort expressed in the uniformity of train delivery to stations, which, in turn, ensures the redistribution of passenger flows at stations and prevents congestion on platforms. Methods. The paper uses methods of automated construction of target metro train schedules that are based on the criteria of train spacing uniformity, as well as uniformity of rolling stock distribution in the process of transition planning, with subsequent redistribution of delay times defined by the automation algorithm over the station-to-station travel times. The method of uniform travel times is based on minimizing the sum of square deviations of departure times for all stations and all trains. The method of vehicle uniformity within transition processes is based on the application of the Euclidean integer division algorithm. When preparing the paper, the authors took into account the fact that metro lines feature systems of various levels of automation regulated by the IEC 62290-1-2014 international standard. Attention was paid not only to transportation systems with high degrees of automation (classified as GoA3 and GoA4 in the standards), but those with low automation (classified as GoA0, GoA1 and GoA2) as well. Results. The method proposed in the paper clearly shows reduced power consumption associated with train traction that is proportional to the durations of delayed departures defined by the automation algorithms of the intelligent automated system for target metro train schedule construction. Conclusions. The presented approach clearly indicates a direct correlation between the energy efficiency of a train schedule and the uniformity of distribution of control actions that adjust train spacing and the durations of the adopted delays, defines the sequences of added/removed units of rolling stock within transition processes, as well as rational night-time train allocation. The materials presented in the paper extend the available knowledge in the field of automation of metro train traffic planning, thus enabling further improvement of the methods of intelligent transportation system design that take into account the deployed highly automated train driving systems (GoA3 and GoA4).

Background: Oro-antral communication (OAC) is a common complication following the extraction of upper molar teeth. The Archer and the Root Sinus (RS) systems can be used to classify impacted teeth in panoramic radiographs. The Archer classes B-D and the Root Sinus classes III, IV have been associated with an increased risk of OAC following tooth extraction in the upper molar region. In our previous study, we found that panoramic radiographs are not reliable for predicting OAC. This study aimed to (1) determine the feasibility of automating the classification (Archer/RS classes) of impacted teeth from panoramic radiographs, (2) determine the distribution of OAC stratified by classification system classes for the purposes of decision tree construction, and (3) determine the feasibility of automating the prediction of OAC utilizing the mentioned classification systems. Methods: We utilized multiple supervised pre-trained machine learning models (VGG16, ResNet50, Inceptionv3, EfficientNet, MobileNetV2), one custom-made convolutional neural network (CNN) model, and a Bag of Visual Words (BoVW) technique to evaluate the performance to predict the clinical classification systems RS and Archer from panoramic radiographs (Aim 1). We then used Chi-square Automatic Interaction Detectors (CHAID) to determine the distribution of OAC stratified by the Archer/RS classes to introduce a decision tree for simple use in clinics (Aim 2). Lastly, we tested the ability of a multilayer perceptron artificial neural network (MLP) and a radial basis function neural network (RBNN) to predict OAC based on the high-risk classes RS III, IV, and Archer B-D (Aim 3). Results: We achieved accuracies of up to 0.771 for EfficientNet and MobileNetV2 when examining the Archer classification. For the AUC, we obtained values of up to 0.902 for our custom-made CNN. In comparison, the detection of the RS classification achieved accuracies of up to 0.792 for the BoVW and an AUC of up to 0.716 for our custom-made CNN. Overall, the Archer classification was detected more reliably than the RS classification when considering all algorithms. CHAID predicted 77.4% correctness for the Archer classification and 81.4% for the RS classification. MLP (AUC: 0.590) and RBNN (AUC: 0.590) for the Archer classification as well as MLP 0.638) and RBNN (0.630) for the RS classification did not show sufficient predictive capability for OAC. Conclusions: The results reveal that impacted teeth can be classified using panoramic radiographs (best AUC: 0.902), and the classification systems can be stratified according to their relationship to OAC (81.4% correct for RS classification). However, the Archer and RS classes did not achieve satisfactory AUCs for predicting OAC (best AUC: 0.638). Additional research is needed to validate the results externally and to develop a reliable risk stratification tool based on the present findings.

One of the main challenges in studying brain signals is the large size of the data due to the use of many electrodes and the time-consuming sampling. Choosing the right dimensional reduction method can lead to a reduction in the data processing time. Evolutionary algorithms are one of the methods used to reduce the dimensions in the field of EEG brain signals, which have shown better performance than other common methods. In this article, (1) a new Bond Graph algorithm (BGA) is introduced that has demonstrated better performance on eight benchmark functions compared to genetic algorithm and particle swarm optimization. Our algorithm has fast convergence and does not get stuck in local optimums. (2) Reductions of features, electrodes, and the frequency range have been evaluated simultaneously for brain signals (left-handed and right-handed). BGA and other algorithms are used to reduce features. (3) Feature extraction and feature selection (with algorithms) for time domain, frequency domain, wavelet coefficients, and autoregression have been studied as well as electrode reduction and frequency interval reduction. (4) First, the features/properties (algorithms) are reduced, the electrodes are reduced, and the frequency range is reduced, which is followed by the construction of new signals based on the proposed formulas. Then, a Common Spatial Pattern is used to remove noise and feature extraction and is classified by a classifier. (5) A separate study with a deep sampling method has been implemented as feature selection in several layers with functions and different window sizes. This part is also associated with reducing the feature and reducing the frequency range. All items expressed in data set IIa from BCI competition IV (the left hand and right hand) have been evaluated between one and three channels, with better results for similar cases (in close proximity). Our method demonstrated an increased accuracy by 5 to 8% and an increased kappa by 5%.

Soft soils are commonly located in many regions near seas, oceans, and rivers all over the world. These regions are vital and attractive for population and governments development. Soft soil is classified as problematic soil owing to sustaining low shear strength and high settlement under structures. Constructing structures and/or infrastructures on soft soil is a considerable risk that needs great attention from structural engineers. The bearing capacity of structure foundations on soft soil depends mainly on their undrained shear strength. This soil feature strongly influences the selection of appropriate soil improvement methods. However, determining undrained shear strength is very difficult, costly, and time-consuming, especially for sensitive clay. Consequently, extracting undisturbed samples of sensitive clay faces several difficulties on construction sites. In this research, accurate field-tested data were fed to advanced machine learning models to predict the undrained shear strength of the sensitive clay to save hard effort, time, repeated laboratory testing, and costs. In this context, a dataset of 111 geotechnical testing points were collected based on laboratory and field examinations of the soil’s key features. These features included the water content, liquid limit, dry unit weight, plasticity index, consistency index, void ratio, specific gravity, and pocket penetration shear. Several machine learning algorithms were adopted to provide the soft clay modeling, including the linear, Gaussian process regression, ensemble and regression trees, and the support vector regression. The coefficient of determination was mainly used to assess the performance of each predictive model. The achieved results revealed that the support vector regression model attained the most accurate prediction for soil undrained shear strength. These outcomes lay the groundwork for evaluating soil shear strength characteristics in a practical, fast, and low-cost way.

Constant demand for new naval and commercial vessels has created special conditions for the Government-owned Soviet shipbuilding industry, which practically has not been affected by the world shipbuilding crisis. On the other hand, such chronic diseases of the centralized economy as lack of incentive, material shortage and poor workmanship cause specific problems for ship construction. Being technically and financially unable to rapidly improve the overall technology level and performance of the entire industry, the Soviets concentrate their efforts on certain important areas and have achieved significant results, especially in welding and cutting titanium and aluminum alloys, modular production methods, standardization, etc. All productivity improvement efforts are supported by an army of highly educated engineers and scientists at shipyards, in multiple scientific, research and design institutions. Discussion Edwin J. Petersen, Todd Pacific Shipyards Three years ago I addressed the Ship Production Symposium as chairman of the Ship Production Committee and outlined some major factors which had contributed to the U.S. shipbuilding industry's remarkable achievements in building and maintaining the world's largest naval and merchant fleets during the five-year period starting just before World War II. The factors were as follows:There was a national commitment to get the job done. The shipbuilding industry was recognized as a needed national resource. There was a dependable workload. Standardization was extensively and effectively utilized. Shipbuilding work was effectively organized. Although these lessons appear to have been lost by our Government since World War II, the paper indicates that the Soviet Union has picked up these principles and has applied them very well to its current shipbuilding program. The paper also gives testimony to the observation that the Soviet Government recognizes the strategic and economic importance of a strong merchant fleet as well as a powerful naval fleet. In reviewing the paper, I found great similarity between the Soviet shipbuilding productivity improvement efforts and our own efforts or goals under the National Shipbuilding Research Program in the following areas:welding technology, flexible automation (robotics), application of group technology, standardization, facilities development, and education and training. In some areas, the Soviet Union appears to be well ahead of the United States in improving the shipbuilding process. Most noteworthy among these is the stable long-and medium-range planning that is possible by virtue of the use and adherence to the "Table of Vessel Classes." It will be obvious to most who hear and read these comments what a vast and significant improvement in shipbuilding costs and schedules could be achieved with a relatively dependable 15year master ship procurement plan for the U.S. naval and merchant fleets. Another area where the Soviet Union appears to lead the United States is in the integration of ship component suppliers into the shipbuilding process. This has been recognized as a vital step by the National Shipbuilding Research Program, but so far we have not made significant progress. A necessary prerequisite for this "supplier integration" is extensive standardization of ship components, yet another area in which the Soviets have achieved significantly greater progress than we have. Additional areas of Soviet advantage are the presence of a multilevel research and development infrastructure well supported by highly educated scientists, engineering and technical personnel; and better integration of formally educated engineering and technical personnel into the ship production process. In his conclusion, the author lists a number of problems facing the Soviet economy that adversely affect shipbuilding productivity. Perhaps behind this listing we can delve out some potential U.S. shipbuilding advantages. First, production systems in U.S. shipyards (with the possible exception of naval shipyards) are probably more flexible and adjustable to meet new circumstances as a consequence of not being constrained by a burdensome centralized bureaucracy, as is the case with Soviet shipyards. Next, such initiatives as the Ship Production Committee's "Human Resources Innovation" projects stand a better chance of achieving product-oriented "production team" relationship among labor, management, and technical personnel than the more rigid Soviet system, especially in view of the ability of U.S. shipyard management to offer meaningful financial incentives without the kind of bureaucratic constraints imposed in the Soviet system. Finally, the current U.S. Navy/shipbuilding industry cooperative effort to develop a common engineering database should lead to a highly integrated and disciplined ship design, construction, operation, and maintenance system for naval ships (and subsequently for commercial ships) that will ultimately restore the U.S. shipbuilding process to a leadership position in the world marketplace (additional references [16] and [17]).On that tentatively positive note, it seems fitting to close this discussion with a question: Is the author aware of any similar Soviet effort to develop an integrated computer-aided design, production and logistics support system? The author is to be congratulated on an excellent, comprehensive insight into the Soviet shipbuilding process and productivity improvement efforts that should give us all adequate cause not to be complacent in our own efforts. Peter M. Palermo, Naval Sea Systems Command The author presents an interesting paper that unfortunately leaves this reader with a number of unanswered questions. The paper is a paradox. It depicts a system consisting of a highly educated work force, advanced fabrication processes including the use of standardized hull modules, sophisticated materials and welding processes, and yet in the author's words they suffer from "low productivity, poor product quality, . . . and the rigid production systems which resists the introduction of new ideas." Is it possible that incentive, motivation, and morale play an equally significant role in achieving quality and producibility advances? Can the author discuss underlying reasons for quality problems in particular—or can we assume that the learning curves of Figs. 5 and Fig. 6 are representative of quality improvement curves? It has been my general impression that quality will improve with application of high-tech fabrication procedures, enclosed fabrication ways, availability of highly educated welding engineers on the building ways, and that productivity would improve with the implementation of modular or zone outfitting techniques coupled with the quality improvements. Can the author give his impressions of the impact of these innovations in the U.S. shipbuilding industry vis-a-vis the Soviet industry? Many of the welding processes cited in the paper are also familiar to the free world, with certain notable exceptions concerning application in Navy shipbuilding. For example, (1) electroslag welding is generally confined to single-pass welding of heavy plates; application to thinner plates—l1/4 in. and less when certified—would permit its use in more applications than heretofore. (2) Electron beam welding is generally restricted to high-technology machinery parts; vacuum chamber size restricts its use for larger components (thus it must be assumed that the Soviets have solved the vacuum chamber problem or have much larger chambers). (3) Likewise, laser welding has had limited use in U.S. shipbuilding. An interesting theme that runs throughout the paper, but is not explicitly addressed, is the quality of Soviet ship fitting. The use of high-tech welding processes and the mention of "remote controlled tooling for welding and X-ray testing the butt, and for following painting" imply significant ship fitting capabilities for fitting and positioning. This is particularly true if modules are built in one facility, outfitted and assembled elsewhere depending on the type of ship required. Any comments concerning Soviet ship fitting capabilities would be appreciated. The discussion on modular construction seems to indicate that the Soviets have a "standard hull module" that is used for different types of vessels, and if the use of these hull modules permit increasing hull length without changes to the fore and aft ends, it can be assumed that they are based on a standard structural design. That being the case, the midship structure will be overdesigned for many applications and optimally designed for very few. Recognizing that the initial additional cost for such a piece of hull structure is relatively minimal, it cannot be forgotten that the lifecycle costs for transporting unnecessary hull weight around can have significant fuel cost impacts. If I perceived the modular construction approach correctly, then I am truly intrigued concerning the methods for handling the distributive systems. In particular, during conversion when the ship is lengthened, how are the electrical, fluid, communications, and other distributive systems broken down, reassembled and tested? "Quick connect couplings" for these type systems at the module breaks is one particular area where economies can be achieved when zone construction methods become the order of the day in U.S. Navy ships. The author's comments in this regard would be most welcome. The design process as presented is somewhat different than U.S. Navy practice. In U.S. practice, Preliminary and Contract design are developed by the Navy. Detail design, the development of the working drawings, is conducted by the lead shipbuilder. While the detail design drawings can be used by follow shipbuilders, flexibility is permitted to facilitate unique shipbuilding or outfitting procedures. Even the contract drawings supplied by the Navy can be modified— upon Navy approval—to permit application of unique shipbuilder capabilities. The large number of college-trained personnel entering the Soviet shipbuilding and allied fields annually is mind-boggling. According to the author's estimation, a minimum of about 6500 college graduates—5000 of which have M.S. degrees—enter these fields each year. It would be most interesting to see a breakdown of these figures—in particular, how many naval architects and welding engineers are included in these figures? These are disciplines with relatively few personnel entering the Navy design and shipbuilding field today. For example, in 1985 in all U.S. colleges and universities, there were only 928 graduates (B.S., M.S. and Ph.D.) in marine, naval architecture and ocean engineering and only 1872 graduates in materials and metallurgy. The number of these graduates that entered the U.S. shipbuilding field is unknown. Again, the author is to be congratulated for providing a very thought-provoking paper. Frank J. Long, Win/Win Strategies This paper serves not only as a chronicle of some of the productivity improvement efforts in Soviet shipbuilding but also as an important reminder of the fruits of those efforts. While most Americans have an appreciation of the strengths of the Russian Navy, this paper serves to bring into clearer focus the Russians' entire maritime might in its naval, commercial, and fishing fleets. Indeed, no other nation on earth has a greater maritime capability. It is generally acknowledged that the Soviet Navy is the largest in the world. When considering the fact that the commercial and fishing fleets are, in many military respects, arms of the naval fleet, we can more fully appreciate how awesome Soviet maritime power truly is. The expansion of its maritime capabilities is simply another but highly significant aspect of Soviet worldwide ambitions. The development and updating of "Setka Typov Su dov" (Table of Vessel Classes), which the author describes is a classic example of the Soviet planning process. As the author states, "A mighty fishing and commercial fleet was built in accordance with a 'Setka' which was originally developed in the 1960's. And an even more impressive example is the rapid expansion of the Soviet Navy." In my opinion it is not mere coincidence that the Russians embarked on this course in the 1960's. That was the beginning of the coldest of cold war periods—Francis Gary Power's U-2 plane was downed by the Russians on May 1, 1960; the mid-May 1960 Four Power Geneva Summit was a bust; the Berlin Wall was erected in 1961 and, in 1962, we had the Cuban Missile Crisis. The United States maritime embargo capability in that crisis undoubtedly influenced the Soviet's planning process. It is a natural and normal function of a state-controlled economy with its state-controlled industries to act to bring about the controlled productivity improvement developments in exactly the key areas discussed in the author's paper. As the author states, "All innovations at Soviet shipyards have originated at two main sources:domestic development andadaptation of new ideas introduced by leading foreign yards, or most likely a combination of both. Soviet shipbuilders are very fast learners; moreover, their own experience is quite substantial." The Ship Production Committee of SNAME has organized its panels to conduct research in many of these same areas for productivity improvement purposes. For example, addressing the areas of technology and equipment are Panels SP-1 and 3, Shipbuilding Facilities and Environmental Effects, and Panel SP-7, Shipbuilding Welding. Shipbuilding methods are the province of SP-2; outfitting and production aids and engineering and scientific support are the province of SP-4, Design Production Integration. As I read through the descriptions of the processes that led to the productivity improvements, I was hoping to learn more about the organizational structure of Soviet shipyards, the managerial hierarchy and how work is organized by function or by craft in the shipyard. (I would assume that for all intents and purposes, all Russian yards are organized in the same way.) American shipyard management is wedded to the notion that American shipbuilding suffers immeasurably from a productivity standpoint because of limitations on management's ability to assign workers across craft lines. It is unlikely that this limitation exists in Soviet shipyards. If it does not, how is the unfettered right of assignment optimized? What are the tangible, measurable results? I believe it would have been helpful, also, for the author to have dedicated some of the paper to one of the most important factors in improvement in the labor-intensive shipbuilding industry—the shipyard worker. There are several references to worker problems—absenteeism, labor shortage, poor workmanship, and labor discipline. The reader is left with the impression that the Russians believe that either those are unsolvable problems or have a priority ranking significantly inferior to the organizational, technical, and design efforts discussed. As a case in point, the author devotes a complete section to engineering education and professional training but makes no mention of education or training programs for blue-collar workers. It would seem that a paper on productivity improvement efforts in Soviet shipbuilding would address this most important element. My guess is that the Russians have considerable such efforts underway and it would be beneficial for us to learn of them.

Environments containing significant concentration of NaCl such as salt lakes harbor extremophiles microorganisms which have a great biotechnology interest. To explore the diversity of Bacteria in Chott Tinsilt (Algeria), an isolation program was performed. Water samples were collected from the saltern during the pre-salt harvesting phase. This Chott is high in salt (22.47% (w/v). Seven halophiles Bacteria were selected for further characterization. The isolated strains were able to grow optimally in media with 10–25% (w/v) total salts. Molecular identification of the isolates was performed by sequencing the 16S rRNA gene. It showed that these cultured isolates included members belonging to the Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus genera with less than 98% of similarity with their closest phylogenetic relative. The halophilic bacterial isolates were also characterized for the production of biosurfactant and industrially important enzymes. Most isolates produced hydrolases and biosurfactants at high salt concentration. In fact, this is the first report on bacterial strains (A4 and B4) which were a good biosurfactant and coagulase producer at 20% and 25% ((w/v)) NaCl. In addition, the biosurfactant produced by the strain B4 at high salinity (25%) was also stable at high temperature (30-100°C) and high alkalinity (pH 11).Key word: Salt Lake, Bacteria, biosurfactant, Chott, halophiles, hydrolases, 16S rRNAINTRODUCTIONSaline lakes cover approximately 10% of the Earth’s surface area. The microbial populations of many hypersaline environments have already been studied in different geographical regions such as Great Salt Lake (USA), Dead Sea (Israel), Wadi Natrun Lake (Egypt), Lake Magadi (Kenya), Soda Lake (Antarctica) and Big Soda Lake and Mono Lake (California). Hypersaline regions differ from each other in terms of geographical location, salt concentration and chemical composition, which determine the nature of inhabitant microorganisms (Gupta et al., 2015). Then low taxonomic diversity is common to all these saline environments (Oren et al., 1993). Halophiles are found in nearly all major microbial clades, including prokaryotic (Bacteria and Archaea) and eukaryotic forms (DasSarma and Arora, 2001). They are classified as slight halophiles when they grow optimally at 0.2–0.85 M (2–5%) NaCl, as moderate halophiles when they grow at 0.85–3.4 M (5–20%) NaCl, and as extreme halophiles when they grow at 3.4–5.1 M (20–30%) NaCl. Hyper saline environments are inhabited by extremely halophilic and halotolerant microorganisms such as Halobacillus sp, Halobacterium sp., Haloarcula sp., Salinibacter ruber , Haloferax sp and Bacillus spp. (Solomon and Viswalingam, 2013). There is a tremendous demand for halophilic bacteria due to their biotechnological importance as sources of halophilic enzymes. Enzymes derived from halophiles are endowed with unique structural features and catalytic power to sustain the metabolic and physiological processes under high salt conditions. Some of these enzymes have been reported to be active and stable under more than one extreme condition (Karan and Khare, 2010). Applications are being considered in a range of industries such as food processing, washing, biosynthetic processes and environmental bioremediation. Halophilic proteases are widely used in the detergent and food industries (DasSarma and Arora, 2001). However, esterases and lipases have also been useful in laundry detergents for the removal of oil stains and are widely used as biocatalysts because of their ability to produce pure compounds. Likewise, amylases are used industrially in the first step of the production of high fructose corn syrup (hydrolysis of corn starch). They are also used in the textile industry in the de-sizing process and added to laundry detergents. Furthermore, for the environmental applications, the use of halophiles for bioremediation and biodegradation of various materials from industrial effluents to soil contaminants and accidental spills are being widely explored. In addition to enzymes, halophilic / halotolerants microorganisms living in saline environments, offer another potential applications in various fields of biotechnology like the production of biosurfactant. Biosurfactants are amphiphilic compounds synthesized from plants and microorganisms. They reduce surface tension and interfacial tension between individual molecules at the surface and interface respectively (Akbari et al., 2018). Comparing to the chemical surfactant, biosurfactant are promising alternative molecules due to their low toxicity, high biodegradability, environmental capability, mild production conditions, lower critical micelle concentration, higher selectivity, availability of resources and ability to function in wide ranges of pH, temperature and salinity (Rocha et al., 1992). They are used in various industries which include pharmaceuticals, petroleum, food, detergents, cosmetics, paints, paper products and water treatment (Akbari et al., 2018). The search for biosurfactants in extremophiles is particularly promising since these biomolecules can adapt and be stable in the harsh environments in which they are to be applied in biotechnology.OBJECTIVESEastern Algeria features numerous ecosystems including hypersaline environments, which are an important source of salt for food. The microbial diversity in Chott Tinsilt, a shallow Salt Lake with more than 200g/L salt concentration and a superficies of 2.154 Ha, has never yet been studied. The purpose of this research was to chemically analyse water samples collected from the Chott, isolate novel extremely or moderate halophilic Bacteria, and examine their phenotypic and phylogenetic characteristics with a view to screening for biosurfactants and enzymes of industrial interest.MATERIALS AND METHODSStudy area: The area is at 5 km of the Commune of Souk-Naâmane and 17 km in the South of the town of Aïn-Melila. This area skirts the trunk road 3 serving Constantine and Batna and the railway Constantine-Biskra. It is part the administrative jurisdiction of the Wilaya of Oum El Bouaghi. The Chott belongs to the wetlands of the High Plains of Constantine with a depth varying rather regularly without never exceeding 0.5 meter. Its length extends on 4 km with a width of 2.5 km (figure 1).Water samples and physico-chemical analysis: In February 2013, water samples were collected from various places at the Chott Tinsilt using Global Positioning System (GPS) coordinates of 35°53’14” N lat. and 06°28’44”E long. Samples were collected randomly in sterile polythene bags and transported immediately to the laboratory for isolation of halophilic microorganisms. All samples were treated within 24 h after collection. Temperature, pH and salinity were measured in situ using a multi-parameter probe (Hanna Instruments, Smithfield, RI, USA). The analytical methods used in this study to measure ions concentration (Ca2+, Mg2+, Fe2+, Na+, K+, Cl−, HCO3−, SO42−) were based on 4500-S-2 F standard methods described elsewhere (Association et al., 1920).Isolation of halophilic bacteria from water sample: The media (M1) used in the present study contain (g/L): 2.0 g of KCl, 100.0/200.0 g of NaCl, 1.0 g of MgSO4.7HO2, 3.0 g of Sodium Citrate, 0.36 g of MnCl2, 10.0 g of yeast extract and 15.0 g agar. The pH was adjusted to 8.0. Different dilutions of water samples were added to the above medium and incubated at 30°C during 2–7 days or more depending on growth. Appearance and growth of halophilic bacteria were monitored regularly. The growth was diluted 10 times and plated on complete medium agar (g/L): glucose 10.0; peptone 5.0; yeast extract 5.0; KH2PO4 5.0; agar 30.0; and NaCl 100.0/200.0. Resultant colonies were purified by repeated streaking on complete media agar. The pure cultures were preserved in 20% glycerol vials and stored at −80°C for long-term preservation.Biochemical characterisation of halophilic bacterial isolates: Bacterial isolates were studied for Gram’s reaction, cell morphology and pigmentation. Enzymatic assays (catalase, oxidase, nitrate reductase and urease), and assays for fermentation of lactose and mannitol were done as described by Smibert (1994).Optimization of growth conditions: Temperature, pH, and salt concentration were optimized for the growth of halophilic bacterial isolates. These growth parameters were studied quantitatively by growing the bacterial isolates in M1 medium with shaking at 200 rpm and measuring the cell density at 600 nm after 8 days of incubation. To study the effect of NaCl on the growth, bacterial isolates were inoculated on M1 medium supplemented with different concentration of NaCl: 1%-35% (w/v). The effect of pH on the growth of halophilic bacterial strains was studied by inoculating isolates on above described growth media containing NaCl and adjusted to acidic pH of 5 and 6 by using 1N HCl and alkaline pH of 8, 9, 10, 11 and 12 using 5N NaOH. The effect of temperature was studied by culturing the bacterial isolates in M1 medium at different temperatures of incubation (4°C–55°C).Screening of halophilic bacteria for hydrolytic enzymes: Hydrolase producing bacteria among the isolates were screened by plate assay on starch, tributyrin, gelatin and DNA agar plates respectively for amylase, lipase, protease and DNAse activities. Amylolytic activity of the cultures was screened on starch nutrient agar plates containing g/L: starch 10.0; peptone 5.0; yeast extract 3.0; agar 30.0; NaCl 100.0/250.0. The pH was 7.0. After incubation at 30 ºC for 7 days, the zone of clearance was determined by flooding the plates with iodine solution. The potential amylase producers were selected based on ratio of zone of clearance diameter to colony diameter. Lipase activity of the cultures was screened on tributyrin nutrient agar plates containing 1% (v/v) of tributyrin. Isolates that showed clear zones of tributyrin hydrolysis were identified as lipase producing bacteria. Proteolytic activity of the isolates was similarly screened on gelatin nutrient agar plates containing 10.0 g/L of gelatin. The isolates showing zones of gelatin clearance upon treatment with acidic mercuric chloride were selected and designated as protease producing bacteria. The presence of DNAse activity on plates was determined on DNAse test agar (BBL) containing 10%-25% (w/v) total salt. After incubation for 7days, the plates were flooded with 1N HCl solution. Clear halos around the colonies indicated DNAse activity (Jeffries et al., 1957).Milk clotting activity (coagulase activity) of the isolates was also determined following the procedure described (Berridge, 1952). Skim milk powder was reconstituted in 10 mM aqueous CaCl2 (pH 6.5) to a final concentration of 0.12 kg/L. Enzyme extracts were added at a rate of 0.1 mL per mL of milk. The coagulation point was determined by manual rotating of the test tube periodically, at short time intervals, and checking for visible clot formation.Screening of halophilic bacteria for biosurfactant production. Oil spread Assay: The Petridis base was filled with 50 mL of distilled water. On the water surface, 20μL of diesel and 10μl of culture were added respectively. The culture was introduced at different spots on the diesel, which is coated on the water surface. The occurrence of a clear zone was an indicator of positive result (Morikawa et al., 2000). The diameter of the oil expelling circles was measured by slide caliber (with a degree of accuracy of 0.02 mm).Surface tension and emulsification index (E24): Isolates were cultivated at 30 °C for 7 days on the enrichment medium containing 10-25% NaCl and diesel oil as the sole carbon source. The medium was centrifuged (7000 rpm for 20 min) and the surface tension of the cell-free culture broth was measured with a TS90000 surface tensiometer (Nima, Coventry, England) as a qualitative indicator of biosurfactant production. The culture broth was collected with a Pasteur pipette to remove the non-emulsified hydrocarbons. The emulsifying capacity was evaluated by an emulsification index (E24). The E24 of culture samples was determined by adding 2 mL of diesel oil to the same amount of culture, mixed for 2 min with a vortex, and allowed to stand for 24 h. E24 index is defined as the percentage of height of emulsified layer (mm) divided by the total height of the liquid column (mm).Biosurfactant stability studies : After growth on diesel oil as sole source of carbone, cultures supernatant obtained after centrifugation at 6,000 rpm for 15 min were considered as the source of crude biosurfactant. Its stability was determined by subjecting the culture supernatant to various temperature ranges (30, 40, 50, 60, 70, 80 and 100 °C) for 30 min then cooled to room temperature. Similarly, the effect of different pH (2–11) on the activity of the biosurfactant was tested. The activity of the biosurfactant was investigated by measuring the emulsification index (El-Sersy, 2012).Molecular identification of potential strains. DNA extraction and PCR amplification of 16S rDNA: Total cellular DNA was extracted from strains and purified as described by Sambrook et al. (1989). DNA was purified using Geneclean® Turbo (Q-BIO gene, Carlsbad, CA, USA) before use as a template in polymerase chain reaction (PCR) amplification. For the 16S rDNA gene sequence, the purified DNA was amplified using a universal primer set, forward primer (27f; 5′-AGA GTT TGA TCM TGG CTC AG) and a reverse primer (1492r; 5′-TAC GGY TAC CTT GTT ACG ACT T) (Lane, 1991). Agarose gel electrophoresis confirmed the amplification product as a 1400-bp DNA fragment.16S rDNA sequencing and Phylogenic analysis: Amplicons generated using primer pair 27f-1492r was sequenced using an automatic sequencer system at Macrogene Company (Seoul, Korea). The sequences were compared with those of the NCBI BLAST GenBank nucleotide sequence databases. Phylogenetic trees were constructed by the neighbor-joining method using MEGA version 5.05 software (Tamura et al., 2011). Bootstrap resembling analysis for 1,000 replicates was performed to estimate the confidence of tree topologies.Nucleotide sequence accession numbers: The nucleotide sequences reported in this work have been deposited in the EMBL Nucleotide Sequence Database. The accession numbers are represented in table 5.Statistics: All experiments were conducted in triplicates. Results were evaluated for statistical significance using ANOVA.RESULTSPhysico-chemical parameters of the collected water samples: The physicochemical properties of the collected water samples are reported in table 1. At the time of sampling, the temperature was 10.6°C and pH 7.89. The salinity of the sample, as determined in situ, was 224.70 g/L (22,47% (w/v)). Chemical analysis of water sample indicated that Na +and Cl- were the most abundant ions (table 1). SO4-2 and Mg+2 was present in much smaller amounts compared to Na +and Cl- concentration. Low levels of calcium, potassium and bicarbonate were also detected, often at less than 1 g/L.Characterization of isolates. Morphological and biochemical characteristic feature of halophilic bacterial isolates: Among 52 strains isolated from water of Chott Tinsilt, seven distinct bacteria (A1, A2, A3, A4, B1, B4 and B5) were chosen for further characterization (table 2). The colour of the isolates varied from beige, pale yellow, yellowish and orange. The bacterial isolates A1, A2, A4, B1 and B5 were rod shaped and gram negative (except B5), whereas A3 and B4 were cocci and gram positive. All strains were oxidase and catalase positive except for B1. Nitrate reductase and urease activities were observed in all the bacterial isolates, except B4. All the bacterial isolates were negative for H2S formation. B5 was the only strain positive for mannitol fermentation (table 2).We isolated halophilic bacteria on growth medium with NaCl supplementation at pH 7 and temperature of 30°C. We studied the effect of NaCl, temperature and pH on the growth of bacterial isolates. All the isolates exhibited growth only in the presence of NaCl indicating that these strains are halophilic. The optimum growth of isolates A3 and B1 was observed in the presence of 10% NaCl, whereas it was 15% NaCl for A1, A2 and B5. A4 and B4 showed optimum growth in the presence of 20% and 25% NaCl respectively. A4, B4 and B5 strains can tolerate up to 35% NaCl.The isolate B1 showed growth in medium supplemented with 10% NaCl and pH range of 7–10. The optimum pH for the growth B1 was 9 and they did not show any detectable growth at or below pH 6 (table 2), which indicates the alkaliphilic nature of B1 isolate. The bacterial isolates A1, A2 and A4 exhibited growth in the range of pH 6–10, while A3 and B4 did not show any growth at pH greater than 8. The optimum pH for growth of all strains (except B1) was pH 7.0 (table 2). These results indicate that A1, A2, A3, A4, B4 and B5 are neutrophilic in nature. All the bacterial isolates exhibited optimal growth at 30°C and no detectable growth at 55°C. Also, detectable growth of isolates A1, A2 and A4 was observed at 4°C. However, none of the bacterial strains could grow below 4°C and above 50°C (table 2).Screening of the halophilic enzymes: To characterize the diversity of halophiles able to produce hydrolytic enzymes among the population of microorganisms inhabiting the hypersaline habitats of East Algeria (Chott Tinsilt), a screening was performed. As described in Materials and Methods, samples were plated on solid media containing 10%-25% (w/v) of total salts and different substrates for the detection of amylase, protease, lipase and DNAse activities. However, coagulase activity was determined in liquid medium using milk as substrate (figure 3). Distributions of hydrolytic activity among the isolates are summarized in table 4.From the seven bacterial isolates, four strains A1, A2, A4 and B5 showed combined hydrolytic activities. They were positive for gelatinase, lipase and coagulase. A3 strain showed gelatinase and lipase activities. DNAse activities were detected with A1, A4, B1 and B5 isolates. B4 presented lipase and coagulase activity. Surprisingly, no amylase activity was detected among all the isolates.Screening for biosurfactant producing isolates: Oil spread assay: The results showed that all the strains could produce notable (>4 cm diameter) oil expelling circles (ranging from 4.11 cm to 4.67 cm). The average diameter for strain B5 was 4.67 cm, significantly (P < 0.05) higher than for the other strains.Surface tension and emulsification index (E24): The assimilation of hydrocarbons as the sole sources of carbon by the isolate strains led to the production of biosurfactants indicated by the emulsification index and the lowering of the surface tension of cell-free supernatant. Based on rapid growth on media containing diesel oil as sole carbon source, the seven isolates were tested for biosurfactant production and emulsification activity. The obtained values of the surface tension measurements as well as the emulsification index (E24) are shown in table 3. The highest reduction of surface tension was achieved with B5 and A3 isolates with values of 25.3 mN m−1 and 28.1 mN m−1 respectively. The emulsifying capacity evaluated by the E24 emulsification index was highest in the culture of isolate B4 (78%), B5 (77%) and A3 (76%) as shown in table 3 and figure 2. These emulsions were stable even after 4 months. The bacteria with emulsification indices higher than 50 % and/or reduction in the surface tension (under 30 mN/m) have been defined as potential biosurfactant producers. Based on surface tension and the E24 index results, isolates B5, B4, A3 and A4 are the best candidates for biosurfactant production. It is important to note that, strains B4 and A4 produce biosurfactant in medium containing respectively 25% and 20% (w/v) NaCl.Stability of biosurfactant activities: The applicability of biosurfactants in several biotechnological fields depends on their stability at different environmental conditions (temperatures, pH and NaCl). For this study, the strain B4 appear very interesting (It can produce biosurfactant at 25 % NaCl) and was choosen for futher analysis for biosurfactant stability. The effects of temperature and pH on the biosurfactant production by the strain B4 are shown in figure 4.biosurfactant in medium containing respectively 25% and 20% (w/v) NaCl.Stability of biosurfactant activities: The applicability of biosurfactants in several biotechnological fields depends on their stability at different environmental conditions (temperatures, pH and NaCl). For this study, the strain B4 appear very interesting (It can produce biosurfactant at 25 % NaCl) and was chosen for further analysis for biosurfactant stability. The effects of temperature and pH on the biosurfactant production by the strain B4 are shown in figure 4. The biosurfactant produced by this strain was shown to be thermostable giving an E-24 Index value greater than 78% (figure 4A). Heating of the biosurfactant to 100 °C caused no significant effect on the biosurfactant performance. Therefore, the surface activity of the crude biosurfactant supernatant remained relatively stable to pH changes between pH 6 and 11. At pH 11, the value of E24 showed almost 76% activity, whereas below pH 6 the activity was decreased up to 40% (figure 4A). The decreases of the emulsification activity by decreasing the pH value from basic to an acidic region; may be due to partial precipitation of the biosurfactant. This result indicated that biosurfactant produced by strain B4 show higher stability at alkaline than in acidic conditions.Molecular identification and phylogenies of potential isolates: To identify halophilic bacterial isolates, the 16S rDNA gene was amplified using gene-specific primers. A PCR product of ≈ 1.3 kb was detected in all the seven isolates. The 16S rDNA amplicons of each bacterial isolate was sequenced on both strands using 27F and 1492R primers. The complete nucleotide sequence of 1336,1374, 1377,1313, 1305,1308 and 1273 bp sequences were obtained from A1, A2, A3, A4, B1, B4 and B5 isolates respectively, and subjected to BLAST analysis. The 16S rDNA sequence analysis showed that the isolated strains belong to the genera Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus as shown in table 5. The halophilic isolates A2 and A4 showed 97% similarity with the Halomonas variabilis strain GSP3 (accession no. AY505527) and the Halomonas sp. M59 (accession no. AM229319), respectively. As for A1, it showed 96% similarity with the Halomonas venusta strain GSP24 (accession no. AY553074). B1 and B4 showed for their part 96% similarity with the Salinivibrio costicola subsp. alcaliphilus strain 18AG DSM4743 (accession no. NR_042255) and the Planococcus citreus (accession no. JX122551), respectively. The bacterial isolate B5 showed 98% sequence similarity with the Halobacillus trueperi (accession no. HG931926), As for A3, it showed only 95% similarity with the Staphylococcus arlettae (accession no. KR047785). The 16S rDNA nucleotide sequences of all the seven halophilic bacterial strains have been submitted to the NCBI GenBank database under the accession number presented in table 5. The phylogenetic association of the isolates is shown in figure 5.DICUSSIONThe physicochemical properties of the collected water samples indicated that this water was relatively neutral (pH 7.89) similar to the Dead Sea and the Great Salt Lake (USA) and in contrast to the more basic lakes such as Lake Wadi Natrun (Egypt) (pH 11) and El Golea Salt Lake (Algeria) (pH 9). The salinity of the sample was 224.70 g/L (22,47% (w/v). This range of salinity (20-30%) for Chott Tinsilt is comparable to a number of well characterized hypersaline ecosystems including both natural and man-made habitats, such as the Great Salt Lake (USA) and solar salterns of Puerto Rico. Thus, Chott Tinsilt is a hypersaline environment, i.e. environments with salt concentrations well above that of seawater. Chemical analysis of water sample indicated that Na +and Cl- were the most abundant ions, as in most hypersaline ecosystems (with some exceptions such as the Dead Sea). These chemical water characteristics were consistent with the previously reported data in other hypersaline ecosystems (DasSarma and Arora, 2001; Oren, 2002; Hacěne et al., 2004). Among 52 strains isolated from this Chott, seven distinct bacteria (A1, A2, A3, A4, B1, B4 and B5) were chosen for phenotypique, genotypique and phylogenetique characterization.The 16S rDNA sequence analysis showed that the isolated strains belong to the genera Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus. Genera obtained in the present study are commonly occurring in various saline habitats across the globe. Staphylococci have the ability to grow in a wide range of salt concentrations (Graham and Wilkinson, 1992; Morikawa et al., 2009; Roohi et al., 2014). For example, in Pakistan, Staphylococcus strains were isolated from various salt samples during the study conducted by Roohi et al. (2014) and these results agreed with previous reports. Halomonas, halophilic and/or halotolerant Gram-negative bacteria are typically found in saline environments (Kim et al., 2013). The presence of Planococcus and Halobacillus has been reported in studies about hypersaline lakes; like La Sal del Rey (USA) (Phillips et al., 2012) and Great Salt Lake (Spring et al., 1996), respectively. The Salinivibrio costicola was a representative model for studies on osmoregulatory and other physiological mechanisms of moderately halophilic bacteria (Oren, 2006).However, it is interesting to note that all strains shared less than 98.7% identity (the usual species cut-off proposed by Yarza et al. (2014) with their closest phylogenetic relative, suggesting that they could be considered as new species. Phenotypic, genetic and phylogenetic analyses have been suggested for the complete identification of these strains. Theses bacterial strains were tested for the production of industrially important enzymes (Amylase, protease, lipase, DNAse and coagulase). These isolates are good candidates as sources of novel enzymes with biotechnological potential as they can be used in different industrial processes at high salt concentration (up to 25% NaCl for B4). Prominent amylase, lipase, protease and DNAase activities have been reported from different hypersaline environments across the globe; e.g., Spain (Sánchez‐Porro et al., 2003), Iran (Rohban et al., 2009), Tunisia (Baati et al., 2010) and India (Gupta et al., 2016). However, to the best of our knowledge, the coagulase activity has never been detected in extreme halophilic bacteria. Isolation and characterization of crude enzymes (especially coagulase) to investigate their properties and stability are in progress.The finding of novel enzymes with optimal activities at various ranges of salt concentrations is of great importance. Besides being intrinsically stable and active at high salt concentrations, halophilic and halotolerant enzymes offer great opportunities in biotechnological applications, such as environmental bioremediation (marine, oilfiel) and food processing. The bacterial isolates were also characterized for production of biosurfactants by oil-spread assay, measurement of surface tension and emulsification index (E24). There are few reports on biosurfactant producers in hypersaline environments and in recent years, there has been a greater increase in interest and importance in halophilic bacteria for biomolecules (Donio et al., 2013; Sarafin et al., 2014). Halophiles, which have a unique lipid composition, may have an important role to play as surface-active agents. The archae bacterial ether-linked phytanyl membrane lipid of the extremely halophilic bacteria has been shown to have surfactant properties (Post and Collins, 1982). Yakimov et al. (1995) reported the production of biosurfactant by a halotolerant Bacillus licheniformis strain BAS 50 which was able to produce a lipopeptide surfactant when cultured at salinities up to 13% NaCl. From solar salt, Halomonas sp. BS4 and Kocuria marina BS-15 were found to be able to produce biosurfactant when cultured at salinities of 8% and 10% NaCl respectively (Donio et al., 2013; Sarafin et al., 2014). In the present work, strains B4 and A4 produce biosurfactant in medium containing respectively 25% and 20% NaCl. To our knowledge, this is the first report on biosurfactant production by bacteria under such salt concentration. Biosurfactants have a wide variety of industrial and environmental applications (Akbari et al., 2018) but their applicability depends on their stability at different environmental conditions. The strain B4 which can produce biosurfactant at 25% NaCl showed good stability in alkaline pH and at a temperature range of 30°C-100°C. Due to the enormous utilization of biosurfactant in detergent manufacture the choice of alkaline biosurfactant is researched (Elazzazy et al., 2015). On the other hand, the interesting finding was the thermostability of the produced biosurfactant even after heat treatment (100°C for 30 min) which suggests the use of this biosurfactant in industries where heating is of a paramount importance (Khopade et al., 2012). To date, more attention has been focused on biosurfactant producing bacteria under extreme conditions for industrial and commercial usefulness. In fact, the biosurfactant produce by strain B4 have promising usefulness in pharmaceutical, cosmetics and food industries and for bioremediation in marine environment and Microbial enhanced oil recovery (MEOR) where the salinity, temperature and pH are high.CONCLUSIONThis is the first study on the culturable halophilic bacteria community inhabiting Chott Tinsilt in Eastern Algeria. Different genera of halotolerant bacteria with different phylogeneticaly characteristics have been isolated from this Chott. Culturing of bacteria and their molecular analysis provides an opportunity to have a wide range of cultured microorganisms from extreme habitats like hypersaline environments. Enzymes produced by halophilic bacteria show interesting properties like their ability to remain functional in extreme conditions, such as high temperatures, wide range of pH, and high salt concentrations. These enzymes have great economical potential in industrial, agricultural, chemical, pharmaceutical, and biotechnological applications. Thus, the halophiles isolated from Chott Tinsilt offer an important potential for application in microbial and enzyme biotechnology. In addition, these halo bacterial biosurfactants producers isolated from this Chott will help to develop more valuable eco-friendly products to the pharmacological and food industries and will be usefulness for bioremediation in marine environment and petroleum industry.ACKNOWLEDGMENTSOur thanks to Professor Abdelhamid Zoubir for proofreading the English composition of the present paper.CONFLICT OF INTERESTThe authors declare that they have no conflict of interest.Akbari, S., N. H. Abdurahman, R. M. Yunus, F. Fayaz and O. R. Alara, 2018. Biosurfactants—a new frontier for social and environmental safety: A mini review. Biotechnology research innovation, 2(1): 81-90.Association, A. P. H., A. W. W. Association, W. P. C. 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Artistic collaboration involves a certain loss of self, because it arises out of the merging of participants. In this sense collaboration questions the notion of the creative individual and the myth of the isolated artistic genius. As such, artistic collaborations can be subversive interventions into the concept of authorship and the ideologies that surround it (Smith 189-194). Collaborations also often simultaneously superimpose many different approaches to the collaborative process. Collaboration is therefore a multiplicitous activity in which different kinds of interactivity are interlinked; this process may also be facilitated by improvisation which allows for continuous modification of the interactions (Smith and Dean, Improvisation). Even when we are writing individually, we are always collaborating with prior texts and employing ideas from others, advice and editing suggestions. This eclectic aspect of creative work has led some to argue that collaboration is the dominant mode, while individual creativity is an illusion (Stillinger; Bennett 94-107). One of the reasons why collaboration tends to be multiplicitous is that contemporary creative endeavour sometimes involves collaboration across different media and with computers. Artworks are created by an ‘assemblage’ of different expertises, media, and machines in which the computer may be a ‘participant’. In this respect contemporary collaboration is what Katherine Hayles calls posthuman: for Hayles ‘the posthuman subject is an amalgam, a collection of heterogeneous components, a material-informational entity whose boundaries undergo continuous construction and reconstruction (Hayles 3). Particularly important here is her argument about the conceptual shifts that information systems are creating. She suggests that the binary of presence and absence is being progressively replaced in cultural and literary thought by the binary of pattern and randomness created by information systems and computer mediation (Hayles 25-49). In other words, we used to be primarily concerned with human interactions, even if sometimes it was the lack of them, as in Roland Barthes concept of ‘the death of the author’. However, this has shifted to our concern with computer systems as methods of organisation. Nevertheless, Hayles argues, computers can never totally replace embodied human subjects, rather we need to continually negotiate between presence and pattern, absence and randomness (Hayles 25-49). This very negotiation is central to many computer-mediated collaborations. Our own collaborative practice—Roger is primarily a musician and Hazel primarily a writer but we both have interdisciplinary performance and technological expertise—spans 15 years and has resulted in approximately 18 collaborative works. They are all cross-media: initially these brought together word and sound; now they sometimes also include image. They all involve multiple forms of collaboration, improvised and unfixed elements, and computer interfaces. Here we want to outline some of the stages in the making of our recent collaboration, Time, the Magician, and its ‘posthuman’ engagement with computerised processes. Time, the Magician is a collaborative performance and sound-video piece. It combines words, sound and image, and involves composed and improvised elements as well as computer mediation. It was conceived largely by us, but the first performance, at the Sydney Conservatorium of Music in 2005 also involved collaboration with Greg White (sound processing) and Sandy Evans (saxophone). The piece begins with a poem by Hazel, initially performed solo, and then juxtaposed with live and improvised sound. This sound involves some real-time and pre-recorded sampling and processing of the voice: this—together with other sonic materials—creates a ‘voicescape’ in which the rhythm, pitch, and timbre of the voice are manipulated and the voice is also spatialised in the performance space (Smith and Dean, “Voicescapes”). The performance of the poem is followed (slightly overlapping) by screened text created in the real-time image-processing program Jitter, and this is also juxtaposed with sound and voice samples. One of the important aspects of the piece is its variability: the video-manipulated text and images change both in order and appearance each time, and the sampling and manipulation of the voice is different too. The example here shows short extracts from the longer performance of the work at the Sydney 2005 event. (This is a Quicktime 7 compressed video of excerpts from the first performance of Time, the Magician by Hazel Smith and Roger Dean. The performance was given by austraLYSIS (Roger Dean, computer sound and image; Sandy Evans, saxophone; Hazel Smith, speaker; Greg White, computer sound and sound projection) at the Sydney Conservatorium of Music, October 2005. The piece in its entirety lasts about 11 minutes, while these excerpts last about four minutes, and are not cross-faded, but simply juxtaposed. The piece itself will later be released elsewhere as a Web video/sound piece, made directly from the sound and the Jitter-processed images which accompany it. This Quicktime 7 performance video uses AAC audio compression (44kHz stereo), H.264 video compression (320x230), and has c. 15fps and 200kbits/sec.; it is prepared for HTTP fast-start streaming. It requires the Quicktime 7 plugin, and on Macintosh works best with Safari or Firefox – Explorer is no longer supported for Macintosh. The total file size is c. 6MB. You can also access the file directly through this link.) All of our collaborations have involved different working processes. Sometimes we start with a particular topic or process in mind, but the process is always explorative and the eventual outcome unpredictable. Usually periods of working individually—often successively rather than simultaneously—alternate with discussion. We will now each describe our different roles in this particular collaboration, and the points of intersection between them. Hazel In creating Time, the Magician we made an initial decision that Roger—who would be responsible for the programming and sound component of the piece—would work with Jitter, which we had successfully used for a previous collaboration. I would write the words, and I decided early on that I would like our collaboration to circle around ideas—which interested both Roger and me—about evolution, movement, emergence, and time. We decided that I would first write some text that would then be used as the basis of the piece, but I had no idea at this stage what form the text would take, and whether I would produce one continuous text or a number of textual fragments. In the early stages I read and ‘collaborated with’ a number of different texts, particularly Elizabeth Grosz’s book The Nick of Time. I was interested in the way Grosz sees Darwin’s work as a treatise on difference—she argues that for Darwin there are no clear-cut distinctions between different species and no absolute origin of the species. I was also stimulated by her idea that political resistance is always potential, if latent, in the repressive regimes or social structures of the past. As I was reading and absorbing the material, I opened a file on my computer and—using a ‘bottom-up’ approach—started to write fragments, sometimes working with the Grosz text as direct trigger. A poem evolved which was a continuous whole but also discontinuous in essence: it consisted of many small fragments that, when glued together and transformed in relation to each other, reverberated though association. This was appropriate, because as the writing process developed I had decided that I would write a poem, but then also disassemble it for the screened version. This way Roger could turn each segment into a module in Jitter, and program the sequence so that the texts would appear in a different order each time. After I had written the poem we decided on a putative structure for the work: the poem would be performed first, the musical element would start about halfway through, and the screened version—with the fragmented texts—would follow. Roger said that he would video some background material to go behind the texts, but he also suggested that I design the texts as visual objects with coloured letters, different fonts, and free spatial arrangements, as I had in some previous multimedia pieces. So I turned the texts into visual designs: this often resulted in my pulling apart sentences, phrases and words and rearranging them. I then converted the texts files into jpg files and gave them to Roger to work on. Roger When Hazel gave me her 32 text images, I turned these into a QuickTime video with 10 seconds per image/frame. I also shot a 5 minute ‘background’ video of vegetation and ground, often moving the camera quickly over blurred objects or zooming in very close to them. The video was then edited as a continually moving sequence with an oscillation between clearly defined and abstracted objects, and between artificial and natural ones. The Jitter interface is constructed largely as a sequence of three processing modules. One of these involves continuously changing the way in which two layers (in this case text and background) are mixed; the second, rotation and feedback of segments from one or both layers; and the third a kind of dripping across the image, with feedback, of segments from one or both layers. The interface is performable, in that the timing and sequence can be altered as the piece progresses, and within any one module most of the parameters are available for performer control—this is the essence of what we call ‘hyperimprovisation’ (Dean). Both text and image layers are ‘granulated’: after a randomly variable length of time—between 2 and 20 seconds or so—there is a jump to a randomly chosen new position in the video, and these jumps occur independently for the two layers. Having established this approach to the image generation, and the overall shape of the piece (as defined above), the remaining aspects were left to the creative choices of the performers. In the Sydney performance both Greg White and I exploited real-time processing of the spoken text by means of the live feed and pre-recorded material. In addition we used long buffers (which contained the present performance of the text) to access the spoken text after Hazel had finished her performed opening segment. I worked on the sound and speech components with some granulation and feedback techniques, throughout, while Greg used a range of other techniques, as well as focusing on the spatial movement of the sound around four loudspeakers surrounding the performance and listening space. Sandy Evans (saxophone)—who was familiar with the overall timeline—improvised freely while viewing the video and listening to our soundscape. In this first performance, while I drove the sound, the computer ‘posthumanly’ (that is without intervention) drove the image. I worked largely with MSP (Max Signal Processing), a part of the MAX/MSP/Jitter suite of platforms for midi, sound and image, to complement sonically the Jitter-mediated video. So processes of granulation, feedback, spatial rotation (of image) or redistribution (of sound)—as well as re-emergence of objects which had been retained in the memory of the computer—were common to both the sound and image manipulation. There was therefore a degree of algorithmic synaesthesia—that is shared algorithms between image and sound (Dean, Whitelaw, Smith, and Worrall). The collaborative process involved a range of stimuli: not only with regard to those of process, as discussed, but also in relation to the ideas in the text Hazel provided. The concepts of evolution, movement, and emergence which were important to her writing also informed and influenced the choice of biological and artificial objects in the background video, and the nature and juxtaposition of the processing modules for both sound and image. Conclusion If we return to the issues raised at the beginning of this article, we can see how our collaboration does involve the merging of participants and the destabilising of the concept of authorship. The poem was not complete after Hazel had written it—or even after she had dislocated it—but is continually reassembled by the Jitter interface that Roger has constructed. The visual images were also produced first by Hazel, then fused with Roger’s video in continuously changing formations through the Jitter interface. The performance may involve collaboration by several people who were not involved in the original conception of the work, indicating how collaboration can become an extended and accumulative process. The collaboration also simultaneously superimposes several different kinds of collaborative process, including the intertextual encounter with the Grosz text; the intermedia fusion of text, image and sound; the participation of a number of different people with differentiated roles and varying degrees of input; and collaboration with the computer. It is an assemblage in the terms mentioned earlier: a continuously modulating conjunction of different expertises, media, and machines. Finally, the collaboration is simultaneously both human and posthuman. It negotiates—in the way Hayles suggests—between pattern, presence, randomness, and absence. On the one hand, it involves human intervention (the writing of the poem, the live music-making, the shooting of the video, the discussion between participants) though sometimes those interventions are hidden, merged, or subsumed. On the other hand, the Jitter interface allows for both tight programming and elements of variability and unpredictability. In this way the collaboration displaces the autonomous subject with what Hayles calls a ‘distributed system’ (Hayles 290). The consequence is that the collaborative process never reaches an endpoint: the computer interface will construct the piece differently each time, we may choose to interact with it in performance, and the sound performance will always contain many improvised and unpredictable elements. The collaborative process, like the work it produces, is ongoing, emergent, and mutating. References Bennett, Andrew. The Author. London: Routledge, 2005. Dean, Roger T. Hyperimprovisation: Computer Interactive Sound Improvisation; with CD-ROM. Madison, WI: A-R Editions, 2003. Dean, Roger, Mitchell Whitelaw, Hazel Smith, and David Worrall. “The Mirage of Real-Time Algorithmic Synaesthesia: Some Compositional Mechanisms and Research Agendas in Computer Music and Sonification.” Contemporary Music Review, in press. Grosz, Elizabeth. The Nick of Time: Politics, Evolution and the Untimely. Sydney: Allen and Unwin, 2004. Hayles, N. Katherine. How We Became Posthuman: Virtual Bodies in Cybernetics, Literature, and Informatics. Chicago: U of Chicago P, 1999. Smith, Hazel. Hyperscapes in the Poetry of Frank O’Hara: Difference, Homosexuality, Topography. Liverpool: Liverpool UP, 2000. Smith, Hazel, and Roger T. Dean. Improvisation, Hypermedia and the Arts since 1945. London: Harwood Academic, 1997. ———. “Voicescapes and Sonic Structures in the Creation of Sound Technodrama.” Performance Research 8.1 (2003): 112-23. Stillinger, Jack. Multiple Authorship and the Myth of Solitary Genius. Oxford: Oxford UP, 1991. Citation reference for this article MLA Style Smith, Hazel, and Roger T. Dean. "Posthuman Collaboration: Multimedia, Improvisation, and Computer Mediation." M/C Journal 9.2 (2006). echo date('d M. Y'); ?> <http://journal.media-culture.org.au/0605/14-smithdean.php>. APA Style Smith, H., and R. Dean. (May 2006) "Posthuman Collaboration: Multimedia, Improvisation, and Computer Mediation," M/C Journal, 9(2). Retrieved echo date('d M. Y'); ?> from <http://journal.media-culture.org.au/0605/14-smithdean.php>.

Wood composites are made from various wood or ligno-cellulosic non-wood materials (shape and origin) that are bonded together using either natural bonding or synthetic resin (e.g. thermoplastic or duroplastic polymers), or organic- (e.g. plastics)/inorganic-binder (e.g. cement). This product mix ranges from panel products (e.g., plywood, particleboard, strandboard, or fiberboard) to engineered timber substitutes (e.g., laminated veneer lumber or structural composite lumber). These composites are used for a number of structural and nonstructural applications in product lines ranging from interior to exterior applications (e.g. furniture and architectural trim in buildings). Wood composite materials can be engineered to meet a range of specific properties. When wood materials and processing variables are properly selected, the result can provide high performance and reliable service. Laminated composites consist of wood veneers bonded with a resin-binder and fabricated with either parallel- (e.g. Laminated Veneer Lumber with higher performance properties parallel to grain) or cross-banded veneers (e.g. plywood, homogenous and with higher dimensional stability). Particle-, strand-, or fiberboard composites are normally classified by density (high, medium, low) and element size. Each is made with a dry woody element, except for fiberboard, which can be made by either dry or wet processes. Hybrid composites based on wood wool, particles, and floor mixed with cement or gypsum are used in construction proving high weathering and fire resistance in construction. The mixture with plastics (PP or PE) and wood floor open a new generation of injected or molded Wood Plastic Composites (WPC), which are able to substitute plastics for some utilizations. In addition, sandwich panels with light core made from plastic foams or honeycomb papers are used in the furniture industry.

Wood composites are made from various wood or ligno-cellulosic non-wood materials (shape and origin) that are bonded together using either natural bonding or synthetic resin (e.g. thermoplastic or duroplastic polymers), or organic- (e.g. plastics)/inorganic-binder (e.g. cement). This product mix ranges from panel products (e.g., plywood, particleboard, strandboard, or fiberboard) to engineered timber substitutes (e.g., laminated veneer lumber or structural composite lumber). These composites are used for a number of structural and nonstructural applications in product lines ranging from interior to exterior applications (e.g. furniture and architectural trim in buildings). Wood composite materials can be engineered to meet a range of specific properties. When wood materials and processing variables are properly selected, the result can provide high performance and reliable service. Laminated composites consist of wood veneers bonded with a resin-binder and fabricated with either parallel- (e.g. Laminated Veneer Lumber with higher performance properties parallel to grain) or cross-banded veneers (e.g. plywood, homogenous and with higher dimensional stability). Particle-, strand-, or fiberboard composites are normally classified by density (high, medium, low) and element size. Each is made with a dry woody element, except for fiberboard, which can be made by either dry or wet processes. Hybrid composites based on wood wool, particles, and floor mixed with cement or gypsum are used in construction proving high weathering and fire resistance in construction. The mixture with plastics (PP or PE) and wood floor open a new generation of injected or molded Wood Plastic Composites (WPC), which are able to substitute plastics for some utilizations. In addition, sandwich panels with light core made from plastic foams or honeycomb papers are used in the furniture industry.