Статті в журналах з теми "Photo-electric processes"

In this paper, the dynamic characteristics of the two approaches of atomic ionization, photo-excitation plus photo-ionization (PE+PI) and the photo-excitation plus electric field ionization (PE+EFI) are investigated systematically. For the PE+PI process, two different schemes (I and II), with and without overlapping pulse duration, are designed and specified. The rate equations for both PE+PI and PE+EFI processes are established, numerical solutions of which provide profound characteristics. A detailed analysis of the theoretical results is carried out to observe the impacts on their overall ionization efficiency made by several factors, either atomic or laser parameters. Not only the ionization efficiency of both approaches is given, but also the optimal selection under some specific conditions is discussed. If the pulse widths of lasers are fixed, then the PE+EFI approach is superior to the PE+PI approach when laser powers are small, while the PE+PI approach is better otherwise.

Photoinduced electron-transfer processes are enhanced or quenched by application of electric fields, depending on the donor–acceptor pairs. Electric-field-induced quenching of photoluminescence, which results from the field-induced dissociation of the exciton state that depends on the photoexcitation wavelength, is observed in π-conjugated polymers. These electric-field effects on photoinduced dynamics have been confirmed by the measurements both of electroabsorption and electrophotoluminescence spectra and of time-resolved electrophotoluminescence decays. Time-resolved measurements of photocurrent, with which novel material function in electrical conductivity of organic materials induced by photo-irradiation and application of electric fields is confirmed, are also reviewed.

In the given paper, the results are presented of the investigation of non-equilibrium stationary carriers system in semiconductor under photo-Gunn effect. It was found that space-homogeneous state of the system is unstable in the case of negative differential conductivity and two waves of space-time perturbations with different phase velocities propagate through the crystal. Phase velocity degeneration conditions have been determined for these waves. Dependence of the complex attenuation decrement on external influences (electric field tension, incident light intensity, semiconductor compensation degree and spectral range) has been investigated in details. State dynamics of inhomogeneous carrier system has been studied using synergetics methods. Obtained results prove that one can controllably switch between the oscillation states of electron subsystem by changing the incident light intensity.

The spin-forbidden photo-ionization of diatomic molecules is proposed. Spin orbit interaction is invoked resulting in the correction and mixing of the wave functions of different multiplicities. The rotation–electronic selection rules given, but not proven, by Dixit and McKoy for Hund's case a based on the conventional mechanism of electric dipole transition (see Chem. Phys. Lett. 128, 49 (1986) are rederived and expressed in a different format. This new format permits the generalization of the selection rules to other photo-ionization transitions caused by the magnetic dipole, the electric quadrupole, and the two- and three-photon operators. These selection rules, which are for transitions from one specific rotational level of a given Kronig reflection symmetry to another, will help understand rotational branching and the dynamics of interaction in the excited state. They will also help in the selective preparation of well-defined rovibronic states in resonant-enhanced multi-photon ionization processes.

At 2 µm wavelengths (149.9 THz), hollow-core photonics band gap fibers have higher light power damage thresholds, stable polarization states, and lower losses of 0.1 dB/km. Additionally, a thulium-doped fiber amplifier can provide a gain of >35 dB. Specifically, an indium-rich InGaAs photodetector shows a naturally higher photoresponsivity at 2 µm wavelengths than the C-band. Therefore, using tunable photo-generated microwave technology at 2 µm wavelengths could achieve higher photo-to-electric power conversion efficiencies for higher RF output power applications using the same method at the same frequency. Here, a double sideband with the carrier suppression modulation method was experimentally applied on 2 µm wavelengths to generate tunable and stable microwave carriers. Comparison experiments were also applied on the 1.55 µm (193.4 THz)/1.31 µm wavelengths (228.8 THz) based on the same indium-rich InGaAs photodetector. Through normalization on the wavelength-corresponded squared external quantum efficiency to visualize the photo-to-electric power conversion efficiency at different wavelengths under the same input optical signal power, the ratio between the results at 2 µm wavelengths and C/O-band is abstracted as 1.31/1.98, approaching theoretical estimations. This corresponds to a power conversion efficiency increasement of ~1.16 dB/~2.98 dB. To our knowledge, this is the first study on 2 micron wavelengths that proves the corresponding high efficiency power conversion property.

Fluorene-thiophene copolymers having chiral and azobenzene substituents, PAzB4-T, were synthesized by the Pd-catalyzed Suzuki coupling method. We studied the aligning organization of the main chain of PAzB4-T with the activation of the attached functional groups by thermal annealing and photo-annealing processes. Circular dichroism (CD) measurements revealed that the thermally annealed PAzB4-T spin-coated films exhibited bisignate Cotton effects over the absorption regions of the polymer main chains and the azobenzene side chains due to the formation of chiral assemblies. After the photo-annealing process, which means linearly polarized light irradiation accompanied by thermal annealing, the PAzB4-T spin-coated films showed linear dichroism over the absorption region of the main chains, due to the alignment of azobenzene side chains against the electric field of the linearly polarized light. These results suggested that rigid conjugated polymers were successfully aligned by the alignment of functional groups with the external stimuli.

The peculiarities of photo-electric processes in thin film CdS/CdTe solar cells (SC) with different back electrodes (Cu/Au, ITO, Cu/ITO) have been studied. As it was established by capacitance – voltage (C – V) characteristics, the potential barrier heights for CdTe/Cu/Au and CdTe/ITO were 0.3 eV and 2.2 eV, respectively. The concentrations of charge carriers near back contact consisted 91020 m–3 and 21021 m–3, respectively. A high carrier concentration and high potential barrier of the ITO back contact caused the tunnel – recombination mechanism of the charge transport. The investigations of CdS/CdTe/ITO SC spectral photosensitivity testify a negative impact of the developed grain-boundary surface of the base layer on the processes of diffusion and separation of non-equilibrium current carriers generated by short-wave radiation. It is shown that the deposition of Cu nanolayer before the deposition of ITO films give stable efficiency 10 % for bifacial CdS/CdTe solar cells.

The performance of Carbon Nanotubes hybrid hydrogels for environmental remediation was investigated using Methylene Blue (MB), Rhodamine B (RD), and Bengal Rose (BR) as model contaminating dyes. An acrylate hydrogel network with incorporated CNT was synthesized by photo-polymerization without any preliminary derivatization of CNT surface. Thermodynamics, isothermal and kinetic studies showed favorable sorption processes with the application of an external 12 V electric field found to be able to influence the amount of adsorbed dyes: stronger interactions with cationic MB molecules (qexp and qexp12 of 19.72 and 33.45 mg g−1, respectively) and reduced affinity for anionic RD (qexp and qexp12 of 28.93 and 13.06 mg g−1, respectively) and neutral BR (qexp and qexp12 of 36.75 and 15.85 mg g−1, respectively) molecules were recorded. The influence of pH variation on dyes adsorption was finally highlighted by reusability studies, with the negligible variation of adsorption capacity after five repeated sorption cycles claiming for the suitability of the proposed systems as effective sorbent for wastewater treatment.

The needs to reduce the imperfection of theoretical and methodological approaches to value and regulate the processes of applying the methods of transactional energy are substantiated. The concept of combining organizational, economic and mathematical models to improve technical, technological and information methods for the effective integration of renewable and traditional energy facilities has been formulated. This determined the goal of forming a digital platform for machine-to-machine automatic processing of transactions. The creation of the platform contributes to solving a number of research tasks including development of schemes for the use of photo and thermoelements for energy generation in distributed energy and control of electrical and thermodynamic parameters of equipment in sensors of its diagnostics and use in electric drives of actuators of the Industrial Internet of Things. The use of big datа and datа science tools is aimed at achieving a number of practical results. Firstly, the differentiation of the composition of capacities and sources in the complex of hybrid energy facilities has been expanded, secondly, possibilities of modeling has been increased. Furthermore, the results of investigation are the model of integration and balancing regulation in the transactional energy platform of the Center for the Coordination of Interest in Complex Objects.

The paper aims to investigate the airflow dynamics of electric-arc spraying (EAS) with airflow pulsation. The study is focused on the dynamic structure of the airflow with an obstacle in the form of crossed electrodes at the steady and the pulsating air supply (with a frequency up to 120 Hz). The work was fulfilled using a computer simulation, the airflow “shadow” photo visualization, and the microstructure characterization of the coatings formed. It was found that when air flows along the crossed electrodes with a gap of 2 mm, a depression zone appears in the flow with a pressure drop from 0.56 MPa to 0.01 MPa. The air pulsation resulted in a change in a flow’s dynamic structure towards an increase in the length of the depression zone, which covers most of the arc, affecting the liquid metal oxidation. It is established that the frequency of a droplet formation should match the frequency of the airflow pulsation to minimize the metal oxidation. With the air pulsating at about 65 Hz, the oxide volume fraction in the aluminum coating was reduced by 3.6 times compared to the steady airflow. EAS with airflow pulsation has the potential for technological cost reduction.

Photonic crystals with periodically arranged structures of ceramics can reflect light or electromagnetic waves through Bragg diffraction and exhibit forbidden gaps in transmission spectra. We have successfully fabricated micro diamond crystals including twined lattices with plane defects to realize wavelength selections in terahertz frequency ranges. Novel smart processing composed of computer aided design, manufacturing and evaluation was established. The terahertz waves are expected to detect micro cracks in material surfaces and structural defects in electric circuits by fine wave interferences, and to analyze cancer cells in human skins and toxic bacteria in natural foods through high frequency excitations. In the fabrication processes using micro patterning stereo-lithography, the photo sensitive resin paste including alumina fine particles were spread on a glass substrate with 10 µm in layer thickness by moving a knife edge, and cross sectional images of ultra violet ray were exposed by using a digital micro mirror device with 2 µm in part accuracy. Through the layer stacking process, micrometer order structures were formed exactly. Dense ceramic components could be obtained through dewaxing and sintering heat treatments. The electromagnetic wave transmission spectra were measured by terahertz wave spectroscopy. The micro diamond lattices could form perfect photonic band gaps opining for all crystal directions. The introduced plane defects realized the wave select resonations. This resonation behavior was visualized and analyzed by finite difference time domain simulations.

The analysis of modern tendencies related to “Smart House” technologies is carried out in this article. The questions of programming languages of microcontrollers and microprocessors are considered. Software products that are used to create mobile applications for smartphones or tablets are presented. A computer system for remote control of room lighting is considered. The design and principle of its operation are shown schematically. A prototype of a computer system that has the following functions: 1) Control, on / off, lighting systems, depending on the needs of the owner of the premises. 2) Transfer of information about the level of illumination to the user, the owner of the premises. 3) Automatic switching on / off of electric, electroluminescent light sources, which are included in the room lighting control system. Photo of the prototype is shown. The principle of operation of the system control program based on the use of a photoresistor is presented. The Arduino microcontroller receives and processes information from the photoresistor, on the basis of which it automatically sends signals to the room lighting control system. The formulas for calculating the illumination using the results of the data obtained from the photoresistor of the prototype are given. The processed information, using wireless networks, goes to the interactive devices of the user, who can remotely check the value of illumination and, if necessary, control it. The visual interface of a mobile application for mobile phones and tablets using the Android operating system is presented. A computer system for controlling the lighting of premises, which is easy to use and does not require significant financial costs, is considered and analyzed. The methods of modeling, observation and research of computer systems are used in the work. The obtained results allow obtaining an effective computer system for remote control of indoor lighting.

Zinc oxide ceramics exhibit various semiconductor properties through optimized elements or materials doping. The elements doping of aluminum or gallium can control the electric conductivity, and composites doping of indium and rare earth such as yttrium can increase the thermoelectric conversion efficiency. In this investigation, dendritic lattice structures of the zinc oxide semiconductors with periodically ordered arrangements or self similar patterns were fabricated successfully to increase the surfaces area and porosity values by using micro patterning stereolithography of a computer aided design and manufacturing. These semiconductor dendrites with penetrable paths and extensive interfaces will be used for fluid and heat flow receptors and applied to the novel sensor devices and energy generators. The dendritic lattice models sliced into a series of cross sectional patterns with uniform thickness by using a stereolithographic file format convertor. These numerical data were transferred into the micro processing equipment. High viscosity slurry material was prepared through the mixing of photo sensitive acrylic resin and the zinc oxide particle at 30 % in volume fraction. The slurry was supplied on a flat substrate with 8 μm in layer thickness by using a mechanical knife edge. The cross sectional image was exposed on the slurry surface by using digital micro mirror devices. Through the layer by layer processes, the solid component was obtained with micrometer order part accuracies. The dense ceramic sample was purchase after de-waxing and sintering process.

Analytical researches of a hybrid solar collecting channel (PVT) are conducted by manufacture electric and thermal energy. The method of researches allows to analyse the following PVT-collector characteristics : a reheat temperature of an absorber and chilling liquid, as well as productivity depending on external and regime working conditions of the device. The work purpose is to work out of a method of calculation of opeating characteristics and definition of rational operating conditions of work of a hybrid solar collecting channel taking into account effective productivity. The complex mathematical model of the local analysis of processes of heat exchange and electrogeneration of a hybrid solar collecting channel for real conditions of a dynamic solar and climatic situation is used. The carried out analysis of heat exchange in alternative conditions showed that efficiency of a heat transport in a collecting channel integral cooling system ηT (a relationship of temperature of an absorber and final temperature of heat-transfer agent) is not a constant and considerably changes under the external and internal factors. It is influenced by intensity of insolation and the heat-transfer agent charge. With growth of these parametres ηT decreases. Existing dependence of electric power of a photo cell on the charge of a chilling liquid is characterised by presence of two expressed sections which are discriminated by rate of a variation of a function. The first of them, with low flux level of a liquid, differs considerable agency of functional parametres. The second one at high intensity differs asymptotic stabilisation of power. The limit values of the transition of the rate of decrease of the function correspond to the fluid flow rate of 0.08...0.085 l/(m2s). These values can be accepted for rationalisation of a refrigerating duty of the photobattery. Generalized dependences for determining the temperature of the liquid at the outlet of the device and the average temperature of the absorber are obtained. These dependences can be used to evaluate the efficiency of conversion of solar energy into electrical and thermal energy in regime optimization problems.

Link for citation: Lukutin B.V., Muravyev D.I. Optimization of operational control of autonomous photo-diesel power supply system with DC bus. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2022, vol. 333, no. 4, рр. 224-235. In Rus. The relevance. An increase in the contribution of renewable energy sources to the generation of the autonomous hybrid energy industry is important in order to reduce the environmental impact of diesel generator plants and decrease operating costs in the production of electrical energy in smart microgrids with distributed generation, including so-called «green» generation. This issue has the highest relevance for cell towers of mobile communication, rotational residential camps, meteorological stations and other remote consumers, the rated capacity of which is tens to hundreds of kW. Objective: the development of computer models for optimizing the management of the operational staff and modes of an autonomous photo-diesel power supply system with a DC bus, so as to make it possible to minimize the operating time of a diesel generator plant by increasing the contribution of the photovoltaic plant at optimal technical and economic indicators. The use of a DC bus for the electricity integration from distributed energy sources is considered promising in reducing the number of hours of inefficient operation of a diesel generator plant, which will make it possible to save diesel fuel and extend the life expectancy of the diesel generator. Novelty. This work expands the known options for modeling and optimizing the modes of a standalone hybrid DC power plant in terms of using an objective function with appropriate restrictions, adapting models of power equipment for the intended purposes of modeling, presenting the structure of a feasibility study based on commercially available characteristics of the elements of the power supply system. Methods. The study entails the development of computer models of the intelligent control architecture of a standalone hybrid power plant including a photovoltaic plant, a diesel generator plant, an electric energy storage system, a remote consumer, as well as auxiliary converter devices. Modeling of control processes is implemented in the Stateflow library, as well as by using the language syntax of the Matlab high-level package, the capabilities of which are acceptable for the intended purposes. Results. The analysis of the results shows that DC PV-diesel power supply systems can be cost-effective in all scenarios that include different types of batteries while for systems without power storage, DC distribution is often not cost-effective. The results will be of interest to specialists developing or operating standalone power supply systems and organizations planning to upgrade existing diesel power plants.

Due to the large size of conventional electrical power transmission systems and the large number of uncertainties involved, achieving the most favourable Transmission Expansion Planning solution turns out to be almost impossible. The proposed method intends to develop a novel method to solve Transmission Expansion Planning problems in electric power systems incorporating renewable energy sources like wind turbines and Photo Voltaic array using IEEE 24 Reliability Test System. For enhancing the efficiency of search processes and to make its use easier on diverse networks and operations, the hybridization of two renowned meta-heuristic algorithms known as Grey Wolf Optimization (GWO) and Genetic Algorithm (GA) termed as Grey Wolf with Genetic Algorithm (GWGA) is adopted. A novel distance factor based on the best position and current position of the solution in Grey wolf optimization is introduced and proposed for the hybridization technique and gives a quick and promising solution with reduced computational time. The GWO and GA algorithms are combined suitably to achieve the advantages of both algorithms. With this proposed model, the investment cost of the transmission line and the maximum amount of power that can be distributed to the consumer is optimized with an objective of minimum load shedding. Among the state-of-the-art optimization techniques considered, a remarkable performance percentage improvement in the expansion plan in terms of cost reduction and load shedding minimization has been obtained in GWO, but when hybridized with GA, an improvement of 13.42% in cost function and 18.65% in load shedding is achieved for a population size of 60. Hence, the proposed method guarantees to generate the best solution with a faster convergence resulting in reduced computational time.

Purpose. Solar energy represents a sensible use alternative of thermal, chemical and nuclear current sources. Solar radiation can satisfy the growing needs of humanity with its energetic resources. Nowadays the actual problem is the development and production, of high-effective and economical photo converters (PC). Thus we need new technologies and materials. Semiconductor PC allows producing solar energy converting in electric with the help of homo-or heterojunctions. About 91 % of falling luminous flux energy is converted into electrical current through the charge carriers release out of semiconductor’s volume. The base of their quality raise is getting high-effective silicon nanostructures, their using will raise considerably PC efficiency. Due to their high efficiency, temperature stability, and low sensitivity to radiation exposure, heterostructure-based photoconverters are the most promising for the use. Methodology. In the article the technology of PC production on the base of silicon structures with heterojunctions ITO/n-Si/n+-Si is proposed. Getting of these layers with the pulverization method on the surface of silicon plates is based on the results of the heating temperature optimal values determination, deposition speed and ITO layer thickness, outflow speed of the gas stream from the spray nozzle, concentration of InCl3 to SnCl4 in spirit and other factors. Results. The represented conception of technology development ITO/n- Si/n+- Si junctions helped to define reasons that determine the character of ITO layer conductivity, depending on SnO2 content in it and their influence on the quality of photoelectrical converters on their base. Originality. The technological peculiarities of getting these layers with pulverization method, operational reliability and efficiency are revealed. Practical value. These tasks solution will lead to the modern technological processes modelling, to the raising of PC quality and, in the case of its consumer properties maintaining, to the use of modern supplies of silicon production and semiconductive materials. References 11, figures 2.

Adiabatic wave (AW) is generated by the effect of two forces, namely centrifugal and Coriolis forces, caused on the reaction of the self-propagating high-temperature synthesis (SHS). The synthesis occurs in the aluminothermic oxide system placed inside the heat insulated cylindrical reactor rotating around a vertical<br />axis. Actually there take place two processes during the SH synthesis: 1. separation of the reaction products, in particular aluminum (corundum) oxide concentrated on a quartz wall of the reactor and forming a tube; 2. formation of a coherent flow of liquid metal particles accelerating in the reactor axis direction according to its rotation speed and co-ordinates of Rх particle in the reactor. The size of the cluster representing particles practically does not change from the very moment of their generation as a result of the reaction due to their motion coherency. Considering the motion speed particles get inside a fresh combustible mixture deeper and deeper and, thus, initiate ignition of the accumulating reaction mixture. This provides growth of the heat release rate and transition of the process to the adiabatic mode. Metal clusters bearing kinetic energy and heat energy of the reaction (T = 2.8-3.5 thousand K) actually have a high energy potential that can increase according to growth of the rotation speed and longitudinal size of the reactor. So, if any highly endothermic reaction mixture takes place within a reactor co-ordinate with exponential growth of the moving clusters energy this reaction can be initiated and consequently will give start to numerous research capabilities. A real possibility of such rare and new materials synthesis technology is illustrated using as an example a reaction of the boron and aluminum oxides attacked by 92 m/s speed moving tungsten clusters with formation of a product from the intermediate boron and aluminum oxides and also tungsten and aluminum borides. The results of the synthesized oxide material study using a radio spectrometer has been presented and presence of free valency in it has been identified. Production of free valency materials is of interest in terms of their mixture with nanomaterilas and their compaction at ultrahigh pressure with the purpose to receive new materials with original mechanical, electric, photo-electric, and other properties. The references given below contain data on this technology studied previously.

The p-NiO/n-ZnO transparent pn heterojunction is prepared by RF magnetron sputtering technique and processed into a chemical sensor element by photolithography pattering and chemical etching process. Forward biased p-NiO/n-ZnO heterojunction sensor can detect VOCs at room temperature and its gas sensitivity is extremely enhanced with the assist of deep UV light incidence. Even if the testing gas is thermodynamically stable such as aromatic VOC, the p-NiO/n-ZnO heterojunction sensor can detect it with the concert mechanism involving “electric” and “photo” assistance.

In order to achieve high quality electrical materials for cable terminations, the crosslinked ethylene-propylene-diene monomer (EPDM) materials, with adequate breakdown strength, appropriately increased conductivity and are developed by employing auxiliary crosslinker and ultraviolet (UV) photoinitiated crosslinking technique. The characteristic cyclic anhydrides with coupled carbonyl groups are utilized as auxiliary crosslinkers to promote crosslinking efficiency and provide polar-groups to EPDM molecules in UV-initiated crosslinking processes, which can be effectively fulfilled in industrial cable production. The results of infrared spectroscopy show that the auxiliary crosslinkers have been successfully grated to EPDM molecules through UV initiation process. The conductivity of EPDM increases after individually utilizing three auxiliary crosslinkers to EPDM at various temperatures of cable operations, by which the highest conductivity has been acquired by grafting N.N-m-phenylene dimaleimide. The first-principles calculations demonstrate that some occupied local electronic-states have been introduced in the band-gap of the EPDM crosslinked by N.N-m-phenylene dimaleimide (EPDM-HAV2), which can be thermally excited from valence band to conduction band at lower temperature or in higher density, leading to augmentation in electrical conductivity. Meanwhile, the breakdown strength achieves a significant improvement in consistency with the theoretical estimation that deeper hole-traps can be introduced by auxiliary-crosslinking modification, and will consequently increase breakdown strength through the trapping mechanism of space charge suppression. in relation to the appropriately increased conductivity, in combination with persistent breakdown strength, the finite element simulations of the electric field distribution in EPDM cable terminations suggest that the effectively homogenized electric field at the root of stress cone will be realized for EPDM-HAV2. The present study offers a fundamental strategy to ameliorate EPDM materials in the application of insulated cable accessories.

The solution-processed TiO2/BiFeO3/BiOI ternary heterojunction with cascade energy level alignments was developed for photoelectrochemical conversion, in which, BiOI was deposited on BiFeO3 sensitized TiO2 mesoporous film by spin-coating method. BiFeO3 as ferroelectric material was served here as a mediator for improvement of charge separation and transfer. The photocurrent generation in TiO2/BiFeO3/BiOI sample are very stable, even measured after 50 light on/off cycles with 2000 s. Moreover, compared with the TiO2/BiOI film, TiO2/BiFeO3/BiOI film showed about twice as high photocurrent density and photocatalytic activity. Kelvin probe force microscope showed that the surface potential of TiO2/BiFeO3/BiOI film was 0.456 V, which was obviously larger than 0.226 V in TiO2/BiOI sample. The increased surface potential should originate from the polarization electric-field E self by BiFeO3 interlayer, in which the direction of electric-field was directed toward the BiOI. The presence of E self consequently resulted in the better dissociation of photo-generated electrons and holes. Charge transport dynamics suggested that charge transfer rate increased from 6.813 s−1 of TiO2/BiOI heterojunction to 22.280 s−1 of TiO2/BiFeO3/BiOI heterojunction, and surface charge recombination rate reduced from 10.305 s−1 of the TiO2/BiOI to 7.707 s−1 of TiO2/BiFeO3/BiOI heterojunction, which results in the enhanced photoelectrochemical conversion in TiO2/BiFeO3/BiOI heterojunction.

In recent years, the research on organic solar cells systems based on nanocomposite containing conjugated polymers has lead to great attention with the aim or replacing conventional inorganic solar cells. This nanocomposite can be processed at lower cost, low weight and ease of synthesis with greater versatility than todays solar cell. In this study, we investigated the dependence of physical, optical and electrical properties on the thickness of MEH-PPV: TiO2 nanocomposite thin films for organic solar cell application. It was found the optical properties of photo-active layer MEH-PPV: TiO2 nanocomposite thin films improved with increasing its thickness however the electrical properties decreased. The absorption coefficients of photoactive layer are high in the visible region (400-600 nm) with optimum absorption region at 500 nm. The shift of absorption edge toward longer wavelength with increased of nanocomposite photoactive layer thickness due to narrowing band gap caused by the effects of electron-electron and electron-impurity scattering. In addition the study of illuminated current-voltage (I-V) characteristics revealed the increment of recombination process with increased of photoactive layer thicknesses. It was found such increased in resistivity from 136x103 to 1600x103 Ω.cm is closely related to the electric field and exciton dissociation which is decreased with increased photoactive thickness.

ABSTRACT Objective To evaluate marginal discrepancies between cast implant superstructure and EDM processed implant structure. Materials and methods For the purpose of this study, an experimental model was prepared on which nine cast implant superstructure in nickel-chromium were fabricated which was then subjected to EDM processing. One-screw test was used to verify fit of superstructure both pre- and post-EDM processing. Photo/Image analyzer was used to evaluate the marginal discrepancy. To reduce the error of measurement, nine readings were taken of each implant abutment junction, i.e. overall 324 readings pre- and post-EDM processing was made. Results All implant superstructure fabricated by investment casting procedure in nickel-chromium alloy showed negative one-screw test, i.e. they were fitting actively on abutment head and were sitting passively after EDM processing. Mean marginal opening of cast implant superstructure before EDM processing was 95.93 microns and 22.76 microns after EDM processing. Conclusion Nickel-chromium alloy can be used for fabrication of implant superstructure with EDM as programmed refining procedure to achieve passive fit. How to cite this article Shah S. Evaluation of Electric Discharge Machining to achieve Passive Fit of Implant Superstructure: An in vitro Study. World J Dent 2012;3(1): 32-36.

Results of measurements made at the SIRIUS beamline of the SOLEIL synchrotron for a new X-ray beam position monitor based on a super-thin single crystal of diamond grown by chemical vapor deposition (CVD) are presented. This detector is a quadrant electrode design processed on a 3 µm-thick membrane obtained by argon–oxygen plasma etching the central area of a CVD-grown diamond plate of 60 µm thickness. The membrane transmits more than 50% of the incident 1.3 keV energy X-ray beam. The diamond plate was of moderate purity (∼1 p.p.m. nitrogen), but the X-ray beam induced current (XBIC) measurements nevertheless showed a photo-charge collection efficiency approaching 100% for an electric field of 2 V µm−1, corresponding to an applied bias voltage of only 6 V. XBIC mapping of the membrane showed an inhomogeneity of more than 10% across the membrane, corresponding to the measured variation in the thickness of the diamond plate before the plasma etching process. The measured XBIC signal-to-dark-current ratio of the device was greater than 105, and the X-ray beam position resolution of the device was better than a micrometer for a 1 kHz sampling rate.

The urgent need for CO2 reduction is calling upon the industry to contribute. However, changes within local energy supply systems including efficiency enhancement are bound to several economical and technical constraints, which results in interfering trade-offs that make it difficult to find the optimal investment option for CO2 mitigation. In this article, a new optimization model is presented that allows to optimize the design and operation of a supply and heat recovery system and production scheduling simultaneously. The model was used for retrofitting of a small brewery’s local energy system to identify decarbonization measures for eight potential future scenarios with different technical, economical and ecological boundary conditions. The results show that the proposed cost-optimized changes to the current energy system only slightly reduce carbon emissions if decarbonization is not enforced since the optimal solutions prioritize integration of photo voltaic (PV) modules that mainly substitute electricity purchase from grid, which is already assumed to be carbon free. However, enforcing decarbonization rates of 50% for the assumed future boundary conditions still results in cost savings compared to the current energy system. These systems contain heat pumps, thermal energy storages, electric boilers, and PV. Battery storages are only part of the optimal system configuration if low to moderate decarbonization rates below 50% are enforced. An analysis of marginal costs for units not considered in the optimal solutions shows that solar thermal collectors only require small decreases in collector cost to be selected by the solver.

Abstract The Saint-Gilles breccias, on the western flank of Piton des Neiges volcano, are clearly identified as debris avalanche deposits. A petrographic, textural and structural analysis of the breccias and inter-bedded autochthonous lava flows enables us to distinguish at least four successive flank slides. The oldest deposit sampled the hydrothermally-altered inner parts of the volcano, and has a large volume. Failure was favored by the presence of a deep intensely-weathered layer. The younger deposits are from superficial sources, as their products are rarely hydrothermalized and are more vesicular. The breccia formation, and especially the progressive breaking up occurring during the debris avalanche displacement, indicates the existence of high speed transport. In the Cap La Houssaye coastal area, abrasion and striation of the underlying lava formation, as well as the packing features observed in the breccia, are considered to be deceleration structures. Introduction Huge landslides of volcano flanks, whether or not initiated by magmatic intrusions, have been recognized as catastrophic events since the 1980 Mount St Helens eruption. On oceanic shield volcanoes, the contribution of failure to the edifice-building process was proposed by Moore [1964] and suggested elsewhere for Hawaii [Lipman et al., 1985 ; Moore et al., 1989], Reunion island [Lénat et al., 1989], Etna [McGuire et al., 1991], and Canarias [Carracedo, 1994, 1996 ; Marty et al., 1996]. This contribution is particularly obvious in island volcanoes showing a U-shaped caldera open to the ocean. Several mechanisms inherent to the causes of failure have been proposed, such as dyke intrusion [McGuire et al., 1990 ; Iverson, 1995 ; Voight and Elsworth, 1997], caldera collapse [Marty et al., 1997], or volcanic spreading [Borgia et al., 1992 ; van Wyk de Vries and Francis, 1997]. Invariably, other factors have been proposed as favorable to volcanic destabilization, such as the probable occurrence of deep low-cohesion layers due to the existence of pyroclastic or hyaloclastic layers [Duffield et al., 1982 ; Siebert, 1984] or an old basement. Gravity spreading models are now frequently proposed to explain the destruction of volcanic edifices [Borgia et al., 1992 ; Merle and Borgia, 1996 ; van Wyk de Vries and Borgia, 1996 ; van Wyk de Vries and Francis, 1997], most of them taking into account basal or intra-volcanic weakness zones. We propose that in such a scenario, density heterogeneity should be an important factor governing the slow evolution of the volcanic pile. Clague and Denlinger [1994] proposed a olivine-rich ductile basal layer that influences the stability of volcano flanks. On Reunion island, a large volcanic landslide has been proposed to explain the peculiar morphology of Piton de la Fournaise-Grand Brûlé [Vincent and Kieffer, 1978]. Bathymetric surveys [Bachèlery and Montagionni, 1983 ; Lénat et al., 1989, 1990 ; Cochonnat et al., 1990 ; Lénat and Labazuy, 1990 ; Labazuy, 1991 ; Bachèlery, 1995 ; Ollier et al., 1998] have confirmed the offshore occurrence of debris avalanche deposits. Similar deposits are also known to exist along the western, northern and southwestern submarine flanks of the Piton des Neiges volcano. Unlike other deposits showing inland prolongation, “Saint-Gilles breccias” displays a well-preserved and non-weathered texture and structure. Because of striking analogies between the “Saint-Gilles breccias” and, for example, the Cantal stratovolcano debris avalanche deposits [Cantagrel, 1995], we conclude that these formations are the products of repeated avalanches during the Piton des Neiges basaltic period [Bachèlery et al., 1996]. We propose an interpretation of their origin, emplacement mechanism and their role in the evolutionary process of the western flank of Piton des Neiges. Volcano-structural setting Mechanical instability of oceanic volcanic edifices generates huge flank landslides, with lateral and mainly submarine transport of sub-aerial materials. These landslides participate in the building of the lower submarine slopes of the volcano. Geophysical surveys have detected low cohesion materials in most offshore Reunion island areas [Malengrau et al., 1999 ; de Voogd et al., 1999 ; Lénat et al., 2001] showing that these materials have largely contributed to the construction of offshore Reunion Island. Such deposits are also found in the inner part (“Cirques”) of Piton des Neiges [Maillot, 1999]. On the other hand, electric and electromagnetic soundings have revealed a deep extending conductor within the Piton de la Fournaise volcanic pile [Courteaud et al., 1997 ; Lenat et al., 2000]. Interpretations about the nature and origin of this conductor depend on its location. In the central caldera zone, as revealed by SP positive anomalies [Malengrau et al., 1994 ; Zlotnicki et al., 1994], the hydrothermal and magmatic complex is probably responsible for the observed low resistivities. Along the flanks, such a hypothesis may not be realistic. Courteaud [1996] suggests the occurrence of a deep argilized layer of volcano-detritic origin. In any case, the hydrothermal complex with high fluid pressures and secondary minerals appears as a potential weak zone that may contribute to the volcano’s instability [Lopez and Williams, 1993 ; Frank, 1995]. Chronology and stratigraphy Extent of the debris avalanche deposits The various breccias found at the western end of Reunion island, on the Piton des Neiges volcano flank, cover a 16 km2 area between Cap Marianne and Saint-Gilles (fig. 1). They are overlain upwards (&gt; 250 to 300 m) by trachyandesitic (mugearite) lava flows of Piton des Neiges differentiated series [Billard, 1974]. Some restricted breccia outcrops in deep valleys from Bernica to the north up to l’Hermitage to the south indicate the existence of larger extension of the debris avalanche deposits. Furthermore, breccias with similar “Saint-Gilles” facies appear down the Maïdo cliff to Mafate “Cirque” at an altitude 1300 m, beneath 600 m of mugearite and some olivine basalt flows. Unpublished electromagnetic data (CSAMT soundings) confirm the inland continuity of the “Saint-Gilles breccias” up to the Maïdo along the Piton des Neiges western flank, hidden by mugearitic flows. Available bathymetric surveys offshore Saint Paul – Saint Gilles areas show the obvious underwater prolongation of “Saint-Gilles breccias” : a shallow depth (&lt; 100 m) plateau followed by a slope with hummocky surface down to 2 500 m depth [Bachèlery et al., 1996 and fig. 2]. From this data, the total surface of “Saint-Gilles” debris avalanche deposits is estimated as more than 500 km2. Chronology A coastal cliff, from Ravine Bernica to Boucan Canot, provides the best outcrop of the northern part of “Saint-Gilles breccias”, with a clear inter-bedding of breccia units and lava formations (photo 1and fig. 3). – The lower breccia unit (Br I), of unknown thickness, has a remarkable friable aspect and a grayish color. – The first autochthonous lava formation (L1) consists in thin pahoehoe olivine basalt flows filling large valleys dug into “Br I”. The top of this formation is striated by the overlying “Br II” unit (photo 2). – Breccia unit “Br II” is interbedded between L1 and L2 olivine basalts. More compact and massive, “Br II” is characterized by a reddish matrix and dark blocks, with many curved fracture surfaces. – On “Br II” or directly on L1, picritic basalt flows L2 are found, filling narrow valleys. – Breccia unit “Br III” lies on “Br II” with a striking sheared contact plane visible along the main road (photo 3). It is a typical debris avalanche deposit with large imbricate blocks within a fine-grained beige matrix. – Once again, basaltic flows of lava formation L3 fill a valley dug into “Br III” near Petite Anse river. – Breccia unit “Br IV” rests on L3 at Petite Anse, but its contact with “Br III” elsewhere is not clear. The facies of this unit is very similar to the “Br III”. All the breccia units are covered by basaltic and trachyandesitic flows from the end of the Piton des Neiges basaltic series, and differentiated series. In the Saint-Gilles river, two formations are superposed : picritic basalts (L4) have flowed on the “Br IV” breccia unit, latter aphyric trachy-andesitic (mugearite) flows (L6) overlapped L4 and the breccia landforms, reaching in places the coastal area. To the north, at Plateau Caillou, plagioclase-phyric basalt flows (L5) are found between mugearite and breccias. Elsewhere on Piton des Neiges, such flows are symptomatic of the transition from the basaltic series to the differentiated series [Billard, 1974]. The occurrence of autochthonous basaltic formations L1 to L3, inter-bedded with “Saint-Gilles breccias”, enables us to distinguish at least four superposed breccia units. Although the emplacement age of the lower “Br I” is not known precisely, it is overlain and therefore older than Cap Marianne pahoehoe lavas (L1) dated at 0.452 Ma [Mc Dougall, 1971]. On the other hand, the upper breccia units are younger than the pahoehoe olivine basalt at Cap la Houssaye dated at 0,435 Ma but older than L5 plagioclasic basalts dated at 0.35 Ma. Geological description of the “breccia sequence” In the synthetic lithologic log (fig. 4) of the Saint-Gilles area, autochthonous lava formations are clearly broken into four separate breccia units. Lava formations. – L1 formation consists of numerous thin pahoehoe olivine-rich to aphyric basaltic flows. Both L2 and L3 formations are characterized by a few thicker (decametric) olivine (frequently picritic) basalt flows. Breccia units. – All breccia units display common characteristics such as the universal association of two facies (photo 4) : (i) a matrix – sandy to silty – facies containing a non-sorted mixture of non-stratified heterogeneous materials ranging from granular size to blocky elements, (ii) coherent large blocks and large pieces (‘block’ facies) of various lithology such as lava flow, scorias, pyroclastics or other breccias ; blocks displaying frequent “jigsaw” features. The lower breccia unit “Br 1” (fig. 4) has a more compact but very heterogeneous aspect, with a chaotic distribution of blocks in a less-developed matrix. This unit is characterized by a deep hydrothermal alteration with a lot of zeolites, chlorite, clays, calcite and oxides. The upper breccia units, “Br II” to “Br IV” (fig. 4) are less heterogeneous than “Br I” because their matrix facies are more voluminous and because the matrix clearly separates the bigger blocks. In both facies, a great diversity of fresh lithologic types such as picritic basalt, olivine-phyric basalt, plagioclase-phyric basalt and aphyric more or less vesicular basalts, gabbro, dunite are found, with no or only few slightly zeolitised blocks. Plurimetric to metric blocks are severely fractured, disintegrated into millimetric to decimetric angular pieces. The frequent polygenic aspect is due to block juxtaposition or imbrication. The abundant matrix is composed of crushed rocks and mineral elements, fine-grained (&lt; mm), showing frequent fluidity and bedding marks (photo 5). The very heterogeneous composition of the matrix is confirmed at a microscopic scale. On the contrary, cores of blocks appear as jigsaw-puzzle-like monolithologic pieces of various basaltic rocks. At their edges, disintegration leads to progressive mixing with neighboring blocks that feed the matrix. Discussion Originality of “Saint-Gilles breccias” “Saint-Gilles breccias” constitute one of the few cases [see also Cantagrel et al., 1999] of debris avalanche deposit outcroppings on the sub-aerial part of an oceanic shield volcano. The main part of the deposit is suspected to be offshore. Their hummocky surface in delineating parallel ridges can be compared to the one described offshore the Grand Brûlé area, east of Piton de la Fournaise [Bachèlery et al., 1996]. “Saint-Gilles breccias” were deposited after several Piton des Neiges flank slide events that were separated by basaltic flows. Repeated debris avalanches have also been proposed to explain Piton de la Fournaise offshore deposits [Lenat et al., 1990 ; Labazuy, 1991]. The occurrence of autochthonous interbedded lava formations is essential to interpret the thick piling up of slide material along Reunion volcano flanks as deposits of repeated avalanches at the same place, instead of as being the products of a single huge event. Many structural and textural features noticed in the upper breccia units reveal crucial information on the emplacement mechanism of debris avalanches. For instance, brecciated blocks are typical of progressive break-up during transport processes. Blocks can simply be fractured, or they can be so severely disintegrated that stretching and mixing with other blocks and matrix formation are observed. The observation of such phenomena implies the existence of numerous percussive events between rocks, as well as internal vibrations in the debris avalanche and therefore the existence of high-speed transport. Lava formations L1 underlying upper breccia units are truncated and strongly striated in a seaward direction (photo 2), parallel to the breccia morphological ridges. In the same way, internal contact surfaces between upper breccia units are shear planes underlain by cataclastic layers and lenses (photo 3). Such structures are interpreted as due to drastic deceleration effects of avalanches reaching a topographic leveling out in the coastal area. This concords with the occurrence of sub-vertical contact areas between the blocks and the matrix. These injections of matrix between the blocks are generated bottom-up from the shear plane at the moment of the sudden deceleration of the avalanche. Other fracture planes that are in accordance with the morphology of ridges, are found in “Br III” unit (see fig. 5). They are interpreted as the result of packing effects. Origin of flank failures Although the source area of breccia formations has not yet been clearly identified, it has to be in the central part of Piton des Neiges as seen in the western cliff of “cirque de Mafate”. Furthermore, “Br I” deeply weathered materials evidently come from the hydrothermalized core of the volcano. Though the “Br I” thickness is not known, the volume involved may be considerable and a part of this volume must constitute the main body of Saint-Gilles offshore deposits. The upper breccias units “Br II” to “Br IV” display very similar textures and lithologies, with dominant non-altered basaltic rocks from the “Phase II” building stage of Piton des Neiges [Billard, 1974]. These units are very thin in the coastal area of Cap La Houssaye (see fig. 2) despite a proximal facies (meaning a deposit in the transport zone nearer than the main deposit zone). They obviously originate from shallow flank slides of restricted extent. We suggest that the upper Saint-Gilles deposits are due to repeated events that produced thin high-speed debris avalanches. Emplacement modalities The morphology of “Saint-Gilles breccias”, or submarine deposits offshore Grand Brûlé (east of Piton de la Fournaise volcano), are typical of sliding movements along shallow depth shear planes (several hundred meters up to two kilometers) within the volcanic pile. But several levels of decollement are suggested by seismic refraction and reflection profiles offshore La Reunion, the deepest corresponding to the top of the preexisting oceanic sediments [de Voogt et al., 1999]. Until now, in Reunion Island, only shallow failures affecting the upper parts of volcanic edifices, with deposits on the lower slopes, have been positively identified. Conditions that trigger giant flank landslides affecting oceanic shields remain poorly understood but we can reasonably speculate that weak hydrothermally-altered layers in the inner part of the volcano favor these gravity-driven processes related to repeated dike injections. The “Saint-Gilles breccia” sequence is considered as a multiphase lateral collapse structure whose first event (“Br I”) was apparently the most voluminous. The corresponding deposit displays frequent hydrothermally-altered material symptomatic of originating from the Piton des Neiges core. Within Piton des Neiges, the low cohesive weathered layer is quite extensive [Nativel, 1978 ; Rançon, 1982] possibly reaching down the volcano flanks [Courteaud et al., 1997]. The interpretative scheme that we propose (fig. 6) in our evaluation of the conditions for the emplacement of Saint-Gilles sequence, takes into account the existence of such a mechanical discontinuity within the volcanic pile. We propose that the massive landslide failure of the west flank of Piton des Neiges volcano that produced the “Br I” breccia, provided efficient channels for younger Piton des Neiges lavas to reach the western and southwestern coastline. Morphological features, as well as radiometric data [Mc Dougall, 1971 ; Gillot and Nativel, 1982] and magnetic surveys [Lénat et al., 2001], yield evidence for preferential accumulation of lava during the last 0.5 m.y. (corresponding mainly to the differentiated series) in this part of the volcano. The relative asymmetry of Piton des Neiges was acquired by rift migration in response to the first huge landslide that produced the “Br I” unit of “Saint-Gilles breccia”, in the manner described by Lipman et al. [1990] for Mauna Loa volcano in Hawaii. The later repetition of flank collapses is consistent with similar structures on other oceanic islands. Since the first lateral collapse, the Piton des Neiges edifice was probably characterized by the existence of an asymmetrical steeper western flank where the old zeolite-rich “Br I” deposits possibly act as a detachment surface for later successive landslides which may have occurred recurrently over a short time interval.

<p>The availability of clean water is a large part of the main problem in the area of West Manggarai Regency, East Nusa Tenggara. Eventhough there is correlation between factors of adequate water, health and economic development. One area that represents this condition is in the village of Labuan Bajo. The enchantment of the tourist island of Flores found in West Manggarai Regency, where Labuan Bajo is the gateway to entering the tourist charm is a place that tourists really want to visit. As a government effort to tighten border supervision and safeguards the Labuan Bajo maritime, the government formed the Indonesian Navy post. Therefore, the availability of clean water is needed in the area, besides to meet the needs of the Labuan Bajo community, improve facilities and infrastructure to bring in many tourists, also for fulfilling the logistical support of the Navy's headquarters. To meet water needs, there are 2 options that are expected to solve the problem, namely (1) mapping of underground water in the village of Labuan Bajo and pumping it using electric power from the voltaic photo results, and (2) when there is no item (1) then pumping water from the reservoir is available at a distance about 3 km from the village of Labuan Bajo. Considering the contour of the area, the needed to make new reservoirs and water pumping systems from the reservoir available, so that an adequate level of water is obtained for drain water to the village. Mapping of underground water is carried out with using the geoelectric method. If option 1 is successful, then the system that is built can be used as a model of pumping underground water, mainly in the area of West Manggarai Regency that needed it. Then the water obtained will be processed through the Reverse Osmosis process to produce ready to drink water.</p><p><strong>Keywords:</strong> clean water supply, photovoltaic, renewable energy, rural area, water pump</p>

Processes that occur inside polar snow cover significantly affect polar atmosphere but they are still poorly understood. Most studies consider photochemistry as the dominant mechanism of chemical transformations but recent field data cannot be interpreted only by such photochemical model. A concept is proposed to consider electric phenomena that are well known to physics but their role was never analyzed by snow chemistry specialists. But there is a question on how to differentiate influences of photo effects and electric phenomena. It can be supposed that these factors are not independent. On the contrary, they reinforce each other and act synergistically.

We study the tunneling mechanism of nonlinear optical processes in solids induced by strong coherent laser fields. The theory is based on an extension of the Landau-Zener model with nonadiabatic geometric effects. In addition to the rectification effect known previously, we find two effects, namely perfect tunneling and counterdiabaticity at fast sweep speed. We apply this theory to the twisted Schwinger effect, i.e., nonadiabatic pair production of particles by rotating electric fields, and find a nonperturbative generation mechanism of the opto-valley polarization and photo-current in Dirac and Weyl fermions.

AbstractSemiconductor nanowire field-effect transistors represent a promising platform for the development of room-temperature (RT) terahertz (THz) frequency light detectors due to the strong nonlinearity of their transfer characteristics and their remarkable combination of low noise-equivalent powers (<1 nW Hz−1/2) and high responsivities (>100 V/W). Nano-engineering an NW photodetector combining high sensitivity with high speed (sub-ns) in the THz regime at RT is highly desirable for many frontier applications in quantum optics and nanophotonics, but this requires a clear understanding of the origin of the photo-response. Conventional electrical and optical measurements, however, cannot unambiguously determine the dominant detection mechanism due to inherent device asymmetry that allows different processes to be simultaneously activated. Here, we innovatively capture snapshots of the photo-response of individual InAs nanowires via high spatial resolution (35 nm) THz photocurrent nanoscopy. By coupling a THz quantum cascade laser to scattering-type scanning near-field optical microscopy (s-SNOM) and monitoring both electrical and optical readouts, we simultaneously measure transport and scattering properties. The spatially resolved electric response provides unambiguous signatures of photo-thermoelectric and bolometric currents whose interplay is discussed as a function of photon density and material doping, therefore providing a route to engineer photo-responses by design.

Abstract In this work, a comprehensive understanding of the relationship of photon absorption, internal electrical field, transport path, and relative kinetics on Sb2S3 photovoltaic performance has been investigated. The n-i-p planar structure for TiO2/Sb2S3/P3HT heterojunction hybrid solar cells was conducted, and the photon-to-electron processes including illumination depth, internal electric field, drift velocity and kinetic energy of charges, photo-generated electrons and hole concentration-related surface potential in Sb2S3, charge transport time, and interfacial charge recombination lifetime were studied to reveal the key factors that governed the device photocurrent. Dark J–V curves, Kelvin probe force microscope, and intensity-modulated photocurrent/photovoltage dynamics indicate that internal electric field is the main factors that affect the photocurrent when the Sb2S3 thickness is less than the hole diffusion length. However, when the Sb2S3 thickness is larger than the hole diffusion length, the inferior area in Sb2S3 for holes that cannot be diffused to P3HT would become a dominant factor affecting the photocurrent. The inferior area in Sb2S3 layer for hole collection could also affect the Voc of the device. The reduced collection of holes in P3HT, when the Sb2S3 thickness is larger than the hole diffusion length, would increase the difference between the quasi-Fermi levels of electrons and holes for a lower Voc.

abstractThe mobility lifetime products for photo-electrons in semi-insulating GaAs, which fit successfully the results of photorefractive studies undertaken in the presence of electric fields are three orders of magnitude smaller than those inferred from transport measurements or from the photorefractive effect with no applied electrical field. Consideration of enhanced recombination via EL2 effective-mass states linked to the L-conduction band minimum allows us to fit the dependence of the photorefractive beam coupling gain coefficient on the grating period for both AC fields and moving gratings. A cascade-capture process, which is three orders of magnitude faster than recombination by multiphonon emission from the Γ band to EL2, leads to greatly reduced mobility-lifetime products for field strengths greater than 1 kV/cm. Our results establish the dominant influence of the EL2 defect properties on the recombination processes essential for modelling and optimizing the photorefractive effect in semi-insulating GaAs.

Our culture abhors the world.Yet Quicksand is swallowing the duellists; the river is threatening the fighter: earth, waters and climate, the mute world, the voiceless things once placed as a decor surrounding the usual spectacles, all those things that never interested anyone, from now on thrust themselves brutally and without warning into our schemes and manoeuvres (Michel Serres, The Natural Contract, p 3). When Michel Serres describes culture's abhorrence of the world in the opening pages of The Natural Contract he draws our attention to the sidelining of nature in histories and theories that have sought to describe Western culture. As Serres argues, cultural histories are quite often built on the debates and struggles of humanity, which are largely held apart from their natural surroundings, as if on a stage, "purified of things" (3). But, as he is at pains to point out, human activity and conflict always take place within a natural milieu, a space of quicksand, swelling rivers, shifting earth, and atmospheric turbulence. Recently, via the potential for vast environmental change, what was once thought of as a staid “nature” has reasserted itself within culture. In this paper I explore how Serres’s positioning of nature can be understood amid new communication systems, which, via the apparent dematerialization of messages, seems to have further removed culture from nature. From here, I focus on a set of artworks that work against this division, reformulating the connection between information, a topic usually considered in relation to media and anthropic communication (and something about which Serres too has a great deal to say), and nature, an entity commonly considered beyond human contrivance. In particular, I explore how information visualisation and sonification has been used to give a new sense of materiality to the atmosphere, repotentialising the air as a natural and informational entity. The Natural Contract argues for the legal legitimacy of nature, a natural contract similar in standing to Rousseau’s social contract. Serres’ss book explores the history and notion of a “legal person”, arguing for a linking of the scientific view of the world and the legal visions of social life, where inert objects and living beings are considered within the same legal framework. As such The Natural Contract does not deal with ecology per-se, but instead focuses on an argument for the inclusion of nature within law (Serres, “A Return” 131). In a drastic reconfiguring of the subject/object relationship, Serres explains how the space that once existed as a backdrop for human endeavour now seems to thrust itself directly into history. "They (natural events) burst in on our culture, which had never formed anything but a local, vague, and cosmetic idea of them: nature" (Serres, The Natural Contract 3). In this movement, nature does not simply take on the role of a new object to be included within a world still dominated by human subjects. Instead, human beings are understood as intertwined with a global system of turbulence that is both manipulated by them and manipulates them. Taking my lead from Serres’s book, in this paper I begin to explore the disconnections and reconnections that have been established between information and the natural environment. While I acknowledge that there is nothing natural about the term “nature” (Harman 251), I use the term to designate an environment constituted by the systematic processes of the collection of entities that are neither human beings nor human crafted artefacts. As the formation of cultural systems becomes demarcated from these natural objects, the scene is set for the development of culturally mediated concepts such as “nature” and “wilderness,” as entities untouched and unspoilt by cultural process (Morton). On one side of the divide the complex of communication systems is situated, on the other is situated “nature”. The restructuring of information flows due to developments in electronic communication has ostensibly removed messages from the medium of nature. Media is now considered within its own ecology (see Fuller; Strate) quite separate from nature, except when it is developed as media content (see Cubitt; Murray; Heumann). A separation between the structures of media ecologies and the structures of natural ecologies has emerged over the history of electronic communication. For instance, since the synoptic media theory of McLuhan it has been generally acknowledged that the shift from script to print, from stone to parchment, and from the printing press to more recent developments such as the radio, telephone, television, and Web2.0, have fundamentally altered the structure and effects of human relationships. However, these developments – “the extensions of man” (McLuhan)— also changed the relationship between society and nature. Changes in communications technology have allowed people to remain dispersed, as ideas, in the form of electric currents or pulses of light travel vast distances and in diverse directions, with communication no longer requiring human movement across geographic space. Technologies such as the telegraph and the radio, with their ability to seemingly dematerialize the media of messages, reformulated the concept of communication into a “quasi-physical connection” across the obstacles of time and space (Clarke, “Communication” 132). Prior to this, the natural world itself was the medium through which information was passed. Rather than messages transmitted via wires, communication was associated with the transport of messages through the world via human movement, with the materiality of the medium measured in the time it took to cover geographic space. The flow of messages followed trade flows (Briggs and Burke 20). Messages moved along trails, on rail, over bridges, down canals, and along shipping channels, arriving at their destination as information. More recently however, information, due to its instantaneous distribution and multiplication across space, seems to have no need for nature as a medium. Nature has become merely a topic for information, as media content, rather than as something that takes part within the information system itself. The above example illustrates a separation between information exchange and the natural environment brought about by a set of technological developments. As Serres points out, the word “media” is etymologically related to the word “milieu”. Hence, a theory of media should be always related to an understanding of the environment (Crocker). But humans no longer need to physically move through the natural world to communicate, ideas can move freely from region to region, from air-conditioned room to air-conditioned room, relatively unimpeded by natural forces or geographic distance. For a long time now, information exchange has not necessitated human movement through the natural environment and this has consequences for how the formation of culture and its location in (or dislocation from) the natural world is viewed. A number of artists have begun questioning the separation between media and nature, particularly concerning the materiality of air, and using information to provide new points of contact between media and the atmosphere (for a discussion of the history of ecoart see Wallen). In Eclipse (2009) (fig. 1) for instance, an internet based work undertaken by the collective EcoArtTech, environmental sensing technology and online media is used experimentally to visualize air pollution. EcoArtTech is made up of the artist duo Cary Peppermint and Leila Nadir and since 2005 they have been inquiring into the relationship between digital technology and the natural environment, particularly regarding concepts such as “wilderness”. In Eclipse, EcoArtTech garner photographs of American national parks from social media and photo sharing sites. Air quality data gathered from the nearest capital city is then inputted into an algorithm that visibly distorts the image based on the levels of particle pollution detected in the atmosphere. The photographs that circulate on photo sharing sites such as Flickr—photographs that are usually rather banal in their adherence to a history of wilderness photography—are augmented by the environmental pollution circulating in nearby capital cities. Figure 1: EcoArtTech, Eclipse (detail of screenshot), 2009 (Internet-based work available at:http://turbulence.org/Works/eclipse/) The digital is often associated with the clean transmission of information, as packets of data move from a server, over fibre optic cables, to be unpacked and re-presented on a computer's screen. Likewise, the photographs displayed in Eclipse are quite often of an unspoilt nature, containing no errors in their exposure or focus (most probably because these wilderness photographs were taken with digital cameras). As the photographs are overlaid with information garnered from air quality levels, the “unspoilt” photograph is directly related to pollution in the natural environment. In Eclipse the background noise of “wilderness,” the pollution in the air, is reframed as foreground. “We breathe background noise…Background noise is the ground of our perception, absolutely uninterrupted, it is our perennial sustenance, the element of the software of all our logic” (Serres, Genesis 7). Noise is activated in Eclipse in a similar way to Serres’s description, as an indication of the wider milieu in which communication takes place (Crocker). Noise links the photograph and its transmission not only to the medium of the internet and the glitches that arise as information is circulated, but also to the air in the originally photographed location. In addition to noise, there are parallels between the original photographs of nature gleaned from photo sharing sites and Serres’s concept of a history that somehow stands itself apart from the effects of ongoing environmental processes. By compartmentalising the natural and cultural worlds, both the historiography that Serres argues against and the wilderness photograph produces a concept of nature that is somehow outside, behind, or above human activities and the associated matter of noise. Eclipse, by altering photographs using real-time data, puts the still image into contact with the processes and informational outputs of nature. Air quality sensors detect pollution in the atmosphere and code these atmospheric processes into computer readable information. The photograph is no longer static but is now open to continual recreation and degeneration, dependent on the coded value of the atmosphere in a given location. A similar materiality is given to air in a public work undertaken by Preemptive Media, titled Areas Immediate Reading (AIR) (fig. 2). In this project, Preemptive Media, made up of Beatriz da Costa, Jamie Schulte and Brooke Singer, equip participants with instruments for measuring air quality as they walked around New York City. The devices monitor the carbon monoxide (CO), nitrogen oxides (NOx) or ground level ozone (O3) levels that are being breathed in by the carrier. As Michael Dieter has pointed out in his reading of the work, the application of sensing technology by Preemptive Media is in distinct contrast to the conventional application of air quality monitoring, which usually takes the form of extremely high resolution located devices spread over great distances. These larger air monitoring networks tend to present the value garnered from a large expanse of the atmosphere that covers individual cities or states. The AIR project, in contrast, by using small mobile sensors, attempts to put people in informational contact with the air that they are breathing in their local and immediate time and place, and allows them to monitor the small parcels of atmosphere that surround other users in other locations (Dieter). It thus presents many small and mobile spheres of atmosphere, inhabited by individuals as they move through the city. In AIR we see the experimental application of an already developed technology in order to put people on the street in contact with the atmospheres that they are moving through. It gives a new informational form to the “vast but invisible ocean of air that surrounds us and permeates us” (Ihde 3), which in this case is given voice by a technological apparatus that converts the air into information. The atmosphere as information becomes less of a vague background and more of a measurable entity that ingresses into the lives and movements of human users. The air is conditioned by information; the turbulent and noisy atmosphere has been converted via technology into readable information (Connor 186-88). Figure 2: Preemptive Media, Areas Immediate Reading (AIR) (close up of device), 2011 Throughout his career Serres has developed a philosophy of information and communication that may help us to reframe the relationship between the natural and cultural worlds (see Brown). Conventionally, the natural world is understood as made up of energy and matter, with exchanges of energy and the flows of biomass through food webs binding ecosystems together (DeLanda 120-1). However, the tendencies and structures of natural systems, like cultural systems, are also dependent on the communication of information. It is here that Serres provides us with a way to view natural and cultural systems as connected by a flow of energy and information. He points out that in the wake of Claude Shannon’s famous Mathematical Theory of Communication it has been possible to consider the relationship between information and thermodynamics, at least in Shannon’s explanation of noise as entropy (Serres, Hermes74). For Serres, an ecosystem can be conceptualised as an informational and energetic system: “it receives, stores, exchanges, and gives off both energy and information in all forms, from the light of the sun to the flow of matter which passes through it (food, oxygen, heat, signals)” (Serres, Hermes 74). Just as we are related to the natural world based on flows of energy— as sunlight is converted into energy by plants, which we in turn convert into food— we are also bound together by flows of information. The task is to find new ways to sense this information, to actualise the information, and imagine nature as more than a welter of data and the air as more than background. If we think of information in broad ranging terms as “coded values of the output of a process” (Losee 254), then we see that information and the environment—as a setting that is produced by continual and energetic processes—are in constant contact. After all, humans sense information from the environment all the time; we constantly decode the coded values of environmental processes transmitted via the atmosphere. I smell a flower, I hear bird songs, and I see the red glow of a sunset. The process of the singing bird is coded as vibrations of air particles that knock against my ear drum. The flower is coded as molecules in the atmosphere enter my nose and bind to cilia. The red glow is coded as wavelengths from the sun are dispersed in the Earth’s atmosphere and arrive at my eye. Information, of course, does not actually exist as information until some observing system constructs it (Clarke, “Information” 157-159). This observing system as we see the sunset, hear the birds, or smell the flower involves the atmosphere as a medium, along with our sense organs and cognitive and non-cognitive processes. The molecules in the atmosphere exist independently of our sense of them, but they do not actualise as information until they are operationalised by the observational system. Prior to this, information can be thought of as noise circulating within the atmosphere. Heinz Von Foester, one of the key figures of cybernetics, states “The environment contains no information. The environment is as it is” (Von Foester in Clarke, “Information” 157). Information, in this model, actualises only when something in the world causes a change to the observational system, as a difference that makes a difference (Bateson 448-466). Air expelled from a bird’s lungs and out its beak causes air molecules to vibrate, introducing difference into the atmosphere, which is then picked up by my ear and registered as sound, informing me that a bird is nearby. One bird song is picked up as information amid the swirling noise of nature and a difference in the air makes a difference to the observational system. It may be useful to think of the purpose of information as to control action and that this is necessary “whenever the people concerned, controllers as well as controlled, belong to an organised social group whose collective purpose is to survive and prosper” (Scarrott 262). Information in this sense operates the organisation of groups. Using this definition rooted in cybernetics, we see that information allows groups, which are dependent on certain control structures based on the sending and receiving of messages through media, to thrive and defines the boundaries of these groups. We see this in a flock of birds, for instance, which forms based on the information that one bird garners from the movements of the other birds in proximity. Extrapolating from this, if we are to live included in an ecological system capable of survival, the transmission of information is vital. But the form of the information is also important. To communicate, for example, one entity first needs to recognise that the other is speaking and differentiate this information from the noise in the air. Following Clarke and Von Foester, an observing system needs to be operational. An art project that gives aesthetic form to environmental processes in this vein—and one that is particularly concerned with the co-agentive relation between humans and nature—is Reiko Goto and Tim Collin’s Plein Air (2010) (fig. 3), an element in their ongoing Eden 3 project. In this work a technological apparatus is wired to a tree. This apparatus, which references the box easels most famously used by the Impressionists to paint ‘en plein air’, uses sensing technology to detect the tree’s responses to the varying CO2 levels in the atmosphere. An algorithm then translates this into real time piano compositions. The tree’s biological processes are coded into the voice of a piano and sensed by listeners as aesthetic information. What is at stake in this work is a new understanding of atmospheres as a site for the exchange of information, and an attempt to resituate the interdependence of human and non-human entities within an experimental aesthetic system. As we breathe out carbon dioxide—both through our physiological process of breathing and our cultural processes of polluting—trees breath it in. By translating these biological processes into a musical form, Collins and Gotto’s work signals a movement from a process of atmospheric exchange to a digital process of sensing and coding, the output of which is then transmitted through the atmosphere as sound. It must be mentioned that within this movement from atmospheric gas to atmospheric music we are not listening to the tree alone. We are listening to a much more complex polyphony involving the components of the digital sensing technology, the tree, the gases in the atmosphere, and the biological (breathing) and cultural processes (cars, factories and coal fired power stations) that produce these gases. Figure 3: Reiko Goto and Tim Collins, Plein Air, 2010 As both Don Ihde and Steven Connor have pointed out, the air that we breathe is not neutral. It is, on the contrary, given its significance in technology, sound, and voice. Taking this further, we might understand sensing technology as conditioning the air with information. This type of air conditioning—as information alters the condition of air—occurs as technology picks up, detects, and makes sensible phenomena in the atmosphere. While communication media such as the telegraph and other electronic information distribution systems may have distanced information from nature, the sensing technology experimentally applied by EcoArtTech, Preeemptive Media, and Goto and Collins, may remind us of the materiality of air. These technologies allow us to connect to the atmosphere; they reformulate it, converting it to information, giving new form to the coded processes in nature.AcknowledgmentAll images reproduced with the kind permission of the artists. References Bateson, Gregory. Steps to an Ecology of Mind. Chicago: University of Chicago Press, 1972. Briggs, Asa, and Peter Burke. A Social History of the Media: From Gutenberg to the Internet. Maden: Polity Press, 2009. Brown, Steve. “Michel Serres: Science, Translation and the Logic of the Parasite.” Theory, Culture and Society 19.1 (2002): 1-27. Clarke, Bruce. “Communication.” Critical Terms for Media Studies. Eds. Mark B. N. Hansen and W. J. T. Mitchell. Chicago: University of Chicago Press, 2010. 131-45 -----. “Information.” Critical Terms for Media Studies. Eds. Mark B. N. Hansen and W. J. T. Mitchell. Chicago: University of Chicago Press, 2010. 157-71 Crocker, Stephen. “Noise and Exceptions: Pure Mediality in Serres and Agamben.” CTheory: 1000 Days of Theory. (2007). 7 June 2012 ‹http://www.ctheory.net/articles.aspx?id=574› Connor, Stephen. The Matter of Air: Science and the Art of the Etheral. London: Reaktion, 2010. Cubitt, Sean. EcoMedia. Amsterdam and New York: Rodopi, 2005 Deiter, Michael. “Processes, Issues, AIR: Toward Reticular Politics.” Australian Humanities Review 46 (2009). 9 June 2012 ‹http://www.australianhumanitiesreview.org/archive/Issue-May-2009/dieter.htm› DeLanda, Manuel. Intensive Science and Virtual Philosophy. London and New York: Continuum, 2002. Fuller, Matthew. Media Ecologies: Materialist Energies in Art and Technoculture. Cambridge, MA: MIT Press, 2005 Harman, Graham. Guerilla Metaphysics. Illinois: Open Court, 2005. Ihde, Don. Listening and Voice: Phenomenologies of Sound. Albany: State University of New York, 2007. Innis, Harold. Empire and Communication. Toronto: Voyageur Classics, 1950/2007. Losee, Robert M. “A Discipline Independent Definition of Information.” Journal of the American Society for Information Science 48.3 (1997): 254–69. McLuhan, Marshall. Understanding Media: The Extensions of Man. London: Sphere Books, 1964/1967. Morton, Timothy. Ecology Without Nature: Rethinking Environmental Aesthetics. Cambridge: Harvard University Press, 2007. Murray, Robin, and Heumann, Joseph. Ecology and Popular Film: Cinema on the Edge. Albany: State University of New York, 2009 Scarrott, G.C. “The Nature of Information.” The Computer Journal 32.3 (1989): 261-66 Serres, Michel. Hermes: Literature, Science Philosophy. Baltimore: The John Hopkins Press, 1982. -----. The Natural Contract. Trans. Elizabeth MacArthur and William Paulson. Ann Arbor: The University of Michigan Press, 1992/1995. -----. Genesis. Trans. Genevieve James and James Nielson. Ann Arbor: The University of Michigan Press, 1982/1995. -----. “A Return to the Natural Contract.” Making Peace with the Earth. Ed. Jerome Binde. Oxford: UNESCO and Berghahn Books, 2007. Strate, Lance. Echoes and Reflections: On Media Ecology as a Field of Study. New York: Hampton Press, 2006 Wallen, Ruth. “Ecological Art: A Call for Intervention in a Time of Crisis.” Leonardo 45.3 (2012): 234-42.

In March 2002, I was visiting the University of Southern California. One night, as sometimes happens on a vibrant campus, two interesting but very different public lectures were scheduled against one another. The first was by the co-chairman and co-founder of Adobe Systems Inc., Dr. John E. Warnock, talking about books. The second was a lecture by acclaimed video artist Bill Viola. The first event was clearly designed as a networking forum for faculty and entrepreneurs. The general student population was conspicuously absent. Warnock spoke of the future of Adobe, shared stories of his love of books, and in an embodiment of the democratising potential of Adobe software (and no doubt to the horror of archivists in the room) he invited the audience to handle extremely rare copies of early printed works from his personal library. In the lecture theatre where Viola was to speak the atmosphere was different. Students were everywhere; even at the price of ten dollars a head. Viola spoke of time and memory in the information age, of consciousness and existence, to an enraptured audience—and showed his latest work. The juxtaposition of these two events says something about our cultural moment, caught between a paradigm modelled on reverence toward the page, and a still emergent sense of medium, intensity and experimentation. But, the juxtaposition yields more. At one point in Warnock’s speech, in a demonstration of the ultra-high resolution possible in the next generation of Adobe products, he presented a scan of a manuscript, two pages, two columns per page, overflowing with detail. Fig. 1. Dr John E. Warnock at the Annenberg Symposium. Photo courtesy of http://www.annenberg.edu/symposia/annenberg/2002/photos.php Later, in Viola’s presentation, a fragment of a video work, Silent Mountain (2001) splits the screen in two columns, matching Warnock’s text: inside each a human figure struggles with intense emotion, and the challenges of bridging the relational gap. Fig. 2. Images from Bill Viola, Silent Mountain (2001). From Bill Viola, THE PASSIONS. The J. Paul Getty Museum, Los Angeles in Association with The National Gallery, London. Ed. John Walsh. p. 44. Both events are, of course, lectures. And although they are different in style and content, a ‘columnular’ scheme informs and underpins both, as a way of presenting and illustrating the lecture. Here, it is worth thinking about Pierre de la Ramée or Petrus (Peter) Ramus (1515-1572), the 16th century educational reformer who in the words of Frances Yates ‘abolished memory as a part of rhetoric’ (229). Ramus was famous for transforming rhetoric through the introduction of his method or dialectic. For Walter J. Ong, whose discussion of Ramism we are indebted to here, Ramus produced the paradigm of the textbook genre. But it is his method that is more noteworthy for us here, organised through definitions and divisions, the distribution of parts, ‘presented in dichotomized outlines or charts that showed exactly how the material was organised spatially in itself and in the mind’ (Ong, Orality 134-135). Fig. 3. Ramus inspired study of Medicine. Ong, Ramus 301. Ong discusses Ramus in more detail in his book Ramus: Method, and the Decay of Dialogue. Elsewhere, Sutton, Benjamin, and I have tried to capture the sense of Ong’s argument, which goes something like the following. In Ramus, Ong traces the origins of our modern, diagrammatic understanding of argument and structure to the 16th century, and especially the work of Ramus. Ong’s interest in Ramus is not as a great philosopher, nor a great scholar—indeed Ong sees Ramus’s work as a triumph of mediocrity of sorts. Rather, his was a ‘reformation’ in method and pedagogy. The Ramist dialectic ‘represented a drive toward thinking not only of the universe but of thought itself in terms of spatial models apprehended by sight’ (Ong, Ramus 9). The world becomes thought of ‘as an assemblage of the sort of things which vision apprehends—objects or surfaces’. Ramus’s teachings and doctrines regarding ‘discoursing’ are distinctive for the way they draw on geometrical figures, diagrams or lecture outlines, and the organization of categories through dichotomies. This sets learning up on a visual paradigm of ‘study’ (Ong, Orality 8-9). Ramus introduces a new organization for discourse. Prior to Ramus, the rhetorical tradition maintained and privileged an auditory understanding of the production of content in speech. Central to this practice was deployment of the ‘seats’, ‘images’ and ‘common places’ (loci communes), stock arguments and structures that had accumulated through centuries of use (Ong, Orality 111). These common places were supported by a complex art of memory: techniques that nourished the practice of rhetoric. By contrast, Ramism sought to map the flow and structure of arguments in tables and diagrams. Localised memory, based on dividing and composing, became crucial (Yates 230). For Ramus, content was structured in a set of visible or sight-oriented relations on the page. Ramism transformed the conditions of visualisation. In our present age, where ‘content’ is supposedly ‘king’, an archaeology of content bears thinking about. In it, Ramism would have a prominent place. With Ramus, content could be mapped within a diagrammatic page-based understanding of meaning. A container understanding of content arises. ‘In the post-Gutenberg age where Ramism flourished, the term “content”, as applied to what is “in” literary productions, acquires a status which it had never known before’ (Ong, Ramus 313). ‘In lieu of merely telling the truth, books would now in common estimation “contain” the truth, like boxes’ (313). For Ramus, ‘analysis opened ideas like boxes’ (315). The Ramist move was, as Ong points out, about privileging the visual over the audible. Alongside the rise of the printing press and page-based approaches to the word, the Ramist revolution sought to re-work rhetoric according to a new scheme. Although spatial metaphors had always had a ‘place’ in the arts of memory—other systems were, however, phonetically based—the notion of place changed. Specific figures such as ‘scheme’, ‘plan’, and ‘table’, rose to prominence in the now-textualised imagination. ‘Structure’ became an abstract diagram on the page disconnected from the total performance of the rhetor. This brings us to another key aspect of the Ramist reformation: that alongside a spatialised organisation of thought Ramus re-works style as presentation and embellishment (Brummett 449). A kind of separation of conception and execution is introduced in relation to performance. In Ramus’ separation of reason and rhetoric, arrangement and memory are distinct from style and delivery (Brummett 464). While both dialectic and rhetoric are re-worked by Ramus in light of divisions and definitions (see Ong, Ramus Chs. XI-XII), and dialectic remains a ‘rhetorical instrument’ (Ramus 290), rhetoric becomes a unique site for simplification in the name of classroom practicality. Dialectic circumscribes the space of learning of rhetoric; invention and arrangement (positioning) occur in advance (289). Ong’s work on the technologisation of the word is strongly focused on identifying the impact of literacy on consciousness. What Ong’s work on Ramus shows is that alongside the so-called printing revolution the Ramist reformation enacts an equally if not more powerful transformation of pedagogic space. Any serious consideration of print must not only look at the technologisation of the word, and the shifting patterns of literacy produced alongside it, but also a particular tying together of pedagogy and method that Ong traces back to Ramus. If, as is canvassed in the call for papers of this issue of M/C Journal, ‘the transitions in print culture are uneven and incomplete at this point’, then could it be in part due to the way Ramism endures and is extended in electronic and hypermedia contexts? Powerpoint presentations, outlining tools (Heim 139-141), and the scourge of bullet points, are the most obvious evidence of greater institutionalization of Ramist knowledge architecture. Communication, and the teaching of communication, is now embedded in a Ramist logic of opening up content like a box. Theories of communication draw on so-called ‘models’ that draw on the representation of the communication process through boxes that divide and define. Perhaps in a less obvious way, ‘spatialized processes of thought and communication’ (Ong, Ramus 314) are essential to the logic of flowcharting and tracking new information structures, and even teaching hypertext (see the diagram in Nielsen 7): a link puts the popular notion that hypertext is close to the way we truly think into an interesting perspective. The notion that we are embedded in print culture is not in itself new, even if the forms of our continual reintegration into print culture can be surprising. In the experience of printing, of the act of pressing the ‘Print’ button, we find ourselves re-integrated into page space. A mini-preview of the page re-assures me of an actuality behind the actualizations on the screen, of ink on paper. As I write in my word processing software, the removal of writing from the ‘element of inscription’ (Heim 136) —the frictionless ‘immediacy’ of the flow of text (152) — is conditioned by a representation called the ‘Page Layout’, the dark borders around the page signalling a kind of structures abyss, a no-go zone, a place, beyond ‘Normal’, from which where there is no ‘Return’. At the same time, however, never before has the technological manipulation of the document been so complex, a part of a docuverse that exists in three dimensions. It is a world that is increasingly virtualised by photocopiers that ‘scan to file’ or ‘scan to email’ rather than good old ‘xeroxing’ style copying. Printing gives way to scanning. In a perverse extension of printing (but also residually film and photography), some video software has a function called ‘Print to Video’. That these super-functions of scanning to file or email are disabled on my department photocopier says something about budgets, but also the comfort with which academics inhabit Ramist space. As I stand here printing my lecture plan, the printer stands defiantly separate from the photocopier, resisting its colonizing convergence even though it is dwarfed in size. Meanwhile, the printer demurely dispenses pages, one at a time, face down, in a gesture of discretion or perhaps embarrassment. For in the focus on the pristine page there is a Puritanism surrounding printing: a morality of blemishes, smudges, and stains; of structure, format and order; and a failure to match that immaculate, perfect argument or totality. (Ong suggests that ‘the term “method” was appropriated from the Ramist coffers and used to form the term “methodists” to designate first enthusiastic preachers who made an issue of their adherence to “logic”’ (Ramus 304).) But perhaps this avoidance of multi-functionality is less of a Ludditism than an understanding that the technological assemblage of printing today exists peripherally to the ideality of the Ramist scheme. A change in technological means does not necessarily challenge the visile language that informs our very understanding of our respective ‘fields’, or the ideals of competency embodied in academic performance and expression, or the notions of content we adopt. This is why I would argue some consideration of Ramism and print culture is crucial. Any ‘true’ breaking out of print involves, as I suggest, a challenge to some fundamental principles of pedagogy and method, and the link between the two. And of course, the very prospect of breaking out of print raises the issue of its desirability at a time when these forms of academic performance are culturally valued. On the surface, academic culture has been a strange inheritor of the Ramist legacy, radically furthering its ambitions, but also it would seem strongly tempering it with an investment in orality, and other ideas of performance, that resist submission to the Ramist ideal. Ong is pessimistic here, however. Ramism was after all born as a pedagogic movement, central to the purveying ‘knowledge as a commodity’ (Ong, Ramus 306). Academic discourse remains an odd mixture of ‘dialogue in the give-and-take Socratic form’ and the scheduled lecture (151). The scholastic dispute is at best a ‘manifestation of concern with real dialogue’ (154). As Ong notes, the ideals of dialogue have been difficult to sustain, and the dominant practice leans towards ‘the visile pole with its typical ideals of “clarity”, “precision”, “distinctness”, and “explanation” itself—all best conceivable in terms of some analogy with vision and a spatial field’ (151). Assessing the importance and after-effects of the Ramist reformation today is difficult. Ong describes it an ‘elusive study’ (Ramus 296). Perhaps Viola’s video, with its figures struggling in a column-like organization of space, structured in a kind of dichotomy, can be read as a glimpse of our existence in or under a Ramist scheme (interestingly, from memory, these figures emote in silence, deprived of auditory expression). My own view is that while it is possible to explore learning environments in a range of ways, and thus move beyond the enclosed mode of study of Ramism, Ramism nevertheless comprises an important default architecture of pedagogy that also informs some higher level assumptions about assessment and knowledge of the field. Software training, based on a process of working through or mimicking a linked series of screenshots and commands is a direct inheritor of what Ong calls Ramism’s ‘corpuscular epistemology’, a ‘one to one correspondence between concept, word and referent’ (Ong, Orality 168). My lecture plan, providing an at a glance view of my presentation, is another. The default architecture of the Ramist scheme impacts on our organisation of knowledge, and the place of performance with in it. Perhaps this is another area where Ong’s fascinating account of secondary orality—that orality that comes into being with television and radio—becomes important (Orality 136). Not only does secondary orality enable group-mindedness and communal exchange, it also provides a way to resist the closure of print and the Ramist scheme, adapting knowledge to new environments and story frameworks. Ong’s work in Orality and Literacy could thus usefully be taken up to discuss Ramism. But this raises another issue, which has to do with the relationship between Ong’s two books. In Orality and Literacy, Ong is careful to trace distinctions between oral, chirographic, manuscript, and print culture. In Ramus this progression is not as prominent— partly because Ong is tracking Ramus’ numerous influences in detail —and we find a more clear-cut distinction between the visile and audile worlds. Yates seems to support this observation, suggesting contra Ong that it is not the connection between Ramus and print that is important, but between Ramus and manuscript culture (230). The interconnections but also lack of fit between the two books suggests a range of fascinating questions about the impact of Ramism across different media/technological contexts, beyond print, but also the status of visualisation in both rhetorical and print cultures. References Brummett, Barry. Reading Rhetorical Theory. Fort Worth: Harcourt, 2000. Heim, Michael. Electric Language: A Philosophical Study of Word Processing. New Haven: Yale UP, 1987. Maras, Steven, David Sutton, and with Marion Benjamin. “Multimedia Communication: An Interdisciplinary Approach.” Information Technology, Education and Society 2.1 (2001): 25-49. Nielsen, Jakob. Multimedia and Hypertext: The Internet and Beyond. Boston: AP Professional, 1995. Ong, Walter J. Orality and Literacy: The Technologizing of the Word. London: Methuen, 1982. —. Ramus: Method, and the Decay of Dialogue. New York: Octagon, 1974. The Second Annual Walter H. Annenberg Symposium. 20 March 2002. http://www.annenberg.edu/symposia/annenberg/2002/photos.php> USC Annenberg Center of Communication and USC Annenberg School for Communication. 22 March 2005. Viola, Bill. Bill Viola: The Passions. Ed. John Walsh. London: The J. Paul Getty Museum, Los Angeles in Association with The National Gallery, 2003. Yates, Frances A. The Art of Memory. Harmondsworth: Penguin, 1969. Citation reference for this article MLA Style Maras, Steven. "Reflections on Adobe Corporation, Bill Viola, and Peter Ramus while Printing Lecture Notes." M/C Journal 8.2 (2005). echo date('d M. Y'); ?> <http://journal.media-culture.org.au/0506/05-maras.php>. APA Style Maras, S. (Jun. 2005) "Reflections on Adobe Corporation, Bill Viola, and Peter Ramus while Printing Lecture Notes," M/C Journal, 8(2). Retrieved echo date('d M. Y'); ?> from <http://journal.media-culture.org.au/0506/05-maras.php>.