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Warehousing challenges require not only effective management but also a new innovative strategy that can significantly improve warehouse efficiency. This study presents an innovative method for solving warehouse problems and achieving low-cost warehousing, based on complementarities between ARIZ (Algorithm for Inventive Problem Solving), lean warehousing approach and discrete event simulation. In the proposed model, the lean warehousing is first used to understand and analyze problems in order to propose solutions that improve warehouse system efficiency. Then, a model of the improved system is developed and analyzed in a predictive simulation software (Witness 1 ), to evaluate its performance. The discrete event simulation allows for experiments on the system to be created and analyzed. Thus, an experimental design was developed to establish the cause-and-effect relationships between the parameters of the system in order to formulate a generalized system of contradictions. And finally, ARIZ is used to address related contradictions for searching for an innovative solution, which must be subsequently implemented and evaluated in the discrete event simulation. The applicability of the proposed method is demonstrated through a case study, involving an automotive company specialized in the manufacturing of electronic modules that wants to reduce raw material warehousing costs. Generally, the aim of the proposed method, which combined lean management, discrete event simulation and the ARIZ algorithm, is to be able to propose solutions that go beyond the limits of continuous improvement and optimization methods. Such an approach enables to propose a kind of continuum between traditional multi-objectives methods and inventive ones.

This article analyses how the status of French poets evolved over a very long period. I draw on Weber to define status as level of social prestige anchored in a community, involving forms of sociability and deferential relations between unequal actors. I show that artists’ status is notably shaped by instances of consecration. I use quantitative and qualitative data to assess poets’ status across the centuries. After being essentially a court occupation, the fall of the Ancien Regime put an end to the longstanding relationship between poetry and the aristocracy, where poets were subordinate in status and depended on nobles for their social existence and prestige. The social history of the arts is most often that of a shift from the patronage system to a market-based organization in which experts (peers and cultural entrepreneurs) along with the public became the main instances of consecration. But unlike novels or fine arts, poetry was unable to establish itself solidly in the market, and the public played little role in shaping poets’ status as opposed to peers. Poets had to find alternative forms of social life, at the expense of growing specialization and a loss of contact with the circles of power; this notably involved new forms of State support, the State remaining a crucial instance of consecration essentially through the education system. This made poets specialists of culture and literature, often holding as a second job positions in the cultural field and the education system. Yet none of this damaged the dynamism of poetry or its social recognition.

Summary Background Since the introduction of the first proton pump inhibitor (PPI) 20 years ago, studies have examined the presence of a rebound effect when this treatment is discontinued. These studies are heterogeneous and contradictory: the last literature review on the rebound in gastric acidity dates from 2006 and did not allow to conclude on the subject. Our objective was to carry out an up-to-date literature review on the existence and characteristics of this gastric acid rebound at the end of PPIs. Methods We conducted a review of the literature on the gastric acid rebound, without excluding the design of the studies. The Medline® databases (PubMed), ISI (Web Of Science) and Google Scholar were queried using the following equation: (“inhibitor proton pump” OR omeprazole OR esomeprazole OR lansoprazole OR pantoprazole OR rabeprazole) AND “rebound” AND “Acid hypersecretion”. Only studies with a measure (whatever it was) before and after treatment were analyzed. Results Of the 131 publications identified, 10 were selected. The design of the studies was very heterogeneous. Five studies concluded a rebound effect. Studies with a treatment duration of less than 4 weeks did not demonstrate a rebound effect. The colonization with Helicobacter pylori masked the appearance of the rebound. Conclusion Daily PPI exposure for more than 4 weeks is likely to trigger a rebound of acid hypersecretion about 15 days after discontinuation, and lasting from a few days to several weeks depending on the duration of the exposure.

During the development of a product, several steps and iterations are necessary for meeting specifications and optimizing performance criteria. This article addresses machining problem, that are faced to increasing constraints and performance criteria. A multi-objective optimization approach is a common approach for determining a solution that meets all these constraints. The Design of Experiments (DoE) is used for modeling and understanding of the process with a minimum of experiences. When the multi-objective optimization approach demonstrates that, for a given design, no single solution exists that optimizes all objectives, the best partial solutions belong to the set of Pareto optimal solutions. In this study, a global approach for determining the optimal solution from a DoE and overcoming this optimum by the complementary use of TRIZ-based methods is proposed. In the proposed approach, optimization and inventive methods are linked. The proposed approach aims to exploit the data from multi-objective optimization and the concept of Pareto optimums to identify ways of modifying a system to respond to more objectives. A new definition of the system of generalized contradictions, which is more complete than previous definitions, is used in the proposed method. This proposal is an illustration of a global research project that aims at linking optimization and inventive methods. An application of this method is proposed for the design of a new cutting tool for the machining of composite materials. Furthermore, the limitations of the method, which proves to be satisfactory in comparison with previously proposed methods, are discussed.

International audience; District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. Abstract Different Transparent Conductive Oxide (TCO) layers properties are evaluated after annealing steps at temperatures above 200°C, in order to study their potential use in crystalline silicon (c-Si) solar cells fabrication processes. While the conductivity of Indium Tin Oxide (ITO) layers obtained by magnetron sputtering (MS) is almost stable after annealing in air, Aluminum doped Zinc Oxide (AZO) layers deposited by Atomic Layer Deposition (ALD) need a controlled atmosphere to maintain high carrier densities and mobilities. During the annealing processes, contaminating atoms (such as Zn) diffuse into the c-Si bulk and may potentially decrease its quality. Thus, both the contamination of the c-Si bulk and the properties of the AZO layer have been analyzed. Abstract Different Transparent Conductive Oxide (TCO) layers properties are evaluated after annealing steps at temperatures above 200°C, in order to study their potential use in crystalline silicon (c-Si) solar cells fabrication processes. While the conductivity of Indium Tin Oxide (ITO) layers obtained by magnetron sputtering (MS) is almost stable after annealing in air, Aluminum doped Zinc Oxide (AZO) layers deposited by Atomic Layer Deposition (ALD) need a controlled atmosphere to maintain high carrier densities and mobilities. During the annealing processes, contaminating atoms (such as Zn) diffuse into the c-Si bulk and may potentially decrease its quality. Thus, both the contamination of the c-Si bulk and the properties of the AZO layer have been analyzed.

A procedure combining electrical measurements (determination of the implied V oc ) and chemical analyses (VPD-ICP-MS) is presented, for the assessment of the wafer surface contamination in a clean room environment, and the identification of the critical elements regarding the fabrication of high efficiency crystalline Si-based homojunction cells. By applying the developed characterization procedure, we highlighted that the daily use of a PVD equipment for the deposition of ITO layers, can induce cross contamination issues, critical for the fabrication of high efficiency crystalline Si-based homojunction solar cells. We showed in this particular case that the degraded performances were due to surface contaminations by In and/or Sn. More precisely for the studied passivation procedure (firing of SiN x :H coated wafers) In and / or Sn would strongly affect the i-V oc (i-V oc 12 cm -2 .

The noncontact crucible (NOC) method was proposed for obtaining Si single bulk crystals with a large diameter and volume using a cast furnace and solar cells with high conversion efficiency and yield. This method has several novel characteristics that originate from its key feature that ingots can be grown inside a Si melt without contact with a crucible wall. Si ingots for solar cells were grown by utilizing the merits resulting from these characteristics. Single ingots with high quality were grown by the NOC method after furnace cleaning, and the minority carrier lifetime was measured to investigate reduction of the number of impurities. A p -type ingot with a convex growth interface in the growth direction was also grown after furnace cleaning. For p -type solar cells prepared using wafers cut from the ingot, the highest and average conversion efficiencies were 19.14% and 19.0%, respectively, which were obtained using the same solar cell structure and process as those employed to obtain a conversion efficiency of 19.1% for a p -type Czochralski (CZ) wafer. Using the cast furnace, solar cells with a conversion efficiency and yield as high as those of CZ solar cells were obtained by the NOC method.

The influence of superficial phosphorus-rich layers during the metallization firing treatment on carrier recombination and trapping in copper contaminated multicrystalline silicon was investigated. Copper contaminated wafers experienced firing steps with and without phosphorus-rich layers. The samples fired without phosphorus emitters feature higher bulk carrier lifetimes, but also a stronger sensitivity to the copper-related light-induced degradation (LID), which was activated by the firing treatment. This last behavior could be used to identify the dominant LID mechanism (boron-oxygen related or copper related) in multicrystalline wafers. In addition, only the samples fired without the phosphorus emitters are subjected to trapping effects, probably involving copper atoms initially precipitated. Copper precipitates are virulent recombination centers whereas the electrical activity of interstitial copper is benign. Therefore these experimental results suggest that on the one hand the wafers fired with the phosphorus-rich layers contain lower interstitial copper concentrations. On the other hand they would feature higher densities of copper precipitates and/or larger copper precipitates.

A significant fraction of Czochralski (Cz) Silicon (Si) wafers suffer from oxygen-related bulk quality issues. The detection of such wafers in the as-cut state during incoming inspection has become a topic of attention as higher efficiency solar cell structures are developing. However such detection - for instance using photoluminescence images – has not yet proven successful due to a high risk of detection errors Shih et al. (2015) [1] . In this work, we tentatively introduce a material quality indicator referred to as “Thermal History Index” (THI) and investigate its ability, in conjunction with the interstitial oxygen concentration ([Oi]), to allow a better identification of low bulk quality wafers.

Understanding the agroecological mechanisms that determine forage yield and quality in intensively managed permanent grasslands is crucial to optimize management and provide environmental and economic benefits to society. In this study, we assessed the relative contribution of climatic, soil and vegetation drivers on forage yield and quality in nine different frequently defoliated and fertilized permanent grasslands used for silage production, that were representative of diverse environmental conditions in Switzerland. Temperature and precipitation, forage yield and quality (i.e., fibers, lignin, carbohydrates, N, P and K contents), relative proportion of plant functional groups, as well as soil nutrient availability and moisture were measured in 2018 (a particularly dry year) during the first three growth cycles. Linear-mixed effect models were performed to test differences among growth cycles on all measured variables and the relationships among them for each cycle. Moreover, a multiple factor analysis (MFA) was performed for each growth cycle to investigate the complex relationships among different sets of variables. Overall, the growth cycle significantly affected all variables, except for forage P content that remained stable over time. Most of the variability in forage yield and quality was explained by climatic conditions and plant functional groups proportion with, however, differences among growth cycles. In the first growth cycle, forage yield and quality were mainly related to the proportion of grasses, precipitation and temperature, then by the proportion of grasses and temperature in the second growth cycle, and finally, by soil nitrogen availability, precipitation and proportion of grasses in the third growth cycle. Overall, in the range of the studied conditions, we found very limited impact of soil nutrient availability on forage yield and quality, except soil N availability during the third growth cycle. Our findings may help prioritize grassland management interventions at specific times during the growing season.

A new application of the differential junction photovoltage (diff-JPV) measurement technique is introduced. The technique's capability to determine the sheet resistance of charge carriers in inversion layers Rs,inv for silicon wafers coated by different dielectrics is investigated. The dielectrics - SiOx, SiNx and AlOx – used in this study are all highly relevant for photovoltaic applications, especially for inversion layer solar cell concepts. The newly developed generalized measurement routine and evaluation utilizing the phase dependent surface potential signals of the diff-JPV sensor resulted in a very rapid Rs,inv extraction even in the very high (>10 kΩ/sq.) Rs,inv range which is typical for inversion layers. However, reference inversion layer sheet resistance values can be hardly obtained without the fabrication of test devices. Thus, to validate the reliability of the diff-JPV measurement an indirect method is applied by measuring the mobility of the inversion charge carriers from the Rs,inv results after sequential surface corona charging steps. A very sharp transition of the diff-JPV results is observed showing significant signal in the inversion regime exclusively and providing Rs,inv results in the expected range. The inversion charge carrier mobility data, calculated from the Rs,inv versus surface charge plots, are consistent and comparable to those found from device tests. Sheet resistance and mobility results exhibit high sensitivity to the surface morphology (i.e, textured versus polished), the interface quality and the amount of charge within the given dielectrics. The contactless JPV is proven to be a fast and efficient way for the rapid characterization of inversion layers properties. It can even be accomplished in production lines in case of future industrialization of inversion layer based solar cell technologies.

International audience; Nowadays, compensated silicon (Si) is used in photovoltaic (PV) processes, whether it is through intentional co-doping of resistivity-adjusted Czochralski ingots for high efficiency n-type Si solar cells, as a result of alternative Si purification processes for the production of low-cost Si feedstock, or as a result of recycling end-of-life materials. Whatever the origin of the compensated Si, the doping concentrations need to be accurately and quickly characterized in order to control such processes. In this work, a rapid and highly sensitive characterization technique based on low temperature Hall Effect measurements is described in scientific details and compared to three well-established chemical methods: Glow Discharge Mass Spectrometry (GDMS), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS), and Secondary Ion Mass Spectrometry (SIMS). The characterized samples were extracted from the n-type top part of a casted solar grade Si ingot. A very good agreement is observed between the dopants densities extracted from the electrical method and from the standard methods. With the advantage of a very low detection limit combined with a short measurement time, the advanced Hall Effect technique is promising for the rapid and accurate characterization of dopant concentrations in compensated Si.

The use of plasma immersion ion implantation (PIII) is a relevant approach for the development of advanced solar cells technologies at lower cost (€/W p ). In this paper, we report on the development of homogeneous boron (B) doping of n-type crystalline silicon (cSi) substrate by the PIII technique. Using diborane (B 2 H 6 ) as gas precursor, various doping profiles were identified fitting the requirements for boron-doped emitters in n-type PERT solar cells. Particularly, saturation current density (J 0e ) of 50 fA/cm 2 were achieved on symmetrical samples for a 94 Ω/sg textured B-emitter passivated with SiO 2 /SiN stack. Bifacial n-type Passivated Emitter Rear Totally-diffused (n-PERT) solar cells were fabricated using the PIII technology and conversion efficiencies up to 19.8% on 239 cm 2 Cz-Si wafers were obtained. As a consequence, these results indicate that PIII can compete with beamline technology but will have lower running cost. It is therefore a promising technology to create high efficiency cSi solar cells.

To help designers to be more inventive during their practice of engineering design, Genrich Altshuller (1926-1998), during the second half of 20th century, developed a set of novel methods, techniques and tools, known as TRIZ. Almost at the same time, Christopher Alexander (born 1936), pursuing a similar goal but in architecture, introduced new concepts, methods and tools for environmental design. If at first, the differences between the thought of Altshuller and the one of Alexander seem important, a thorough analysis shows striking similarities. In this paper, we first analyze two analogue concepts: the recurrent patterns of problem solving and the constant tendencies of evolution. This analysis will propose five axes to compare the two theoretical corpuses. And then, based on these axes, the differences in terms of goals, principles and outputs will be identified. One of the aims of such comparison is to analyze the potential cross-fertilization between these theories, built in two fields of design. While the similarities, pointing out the common basic concepts in architecture and engineering, might facilitate developing a knowledge base integrating the phenomena of both domains, their divergence could point out the research fields for researchers interested in improving the practice of design regardless of its domain of application.

Differences in aluminum concentration profile in the doped layer are found not to account for the differences in photovoltaic conversion efficiency (0.8% absolute) observed between homo-junction solar cells made with mono-like p-type silicon using three different screen-printed Al pastes to create the back-surface field (BSF) and electrical contact. X-ray Bragg diffraction imaging (XRDI; topography) in section and X-ray nano-diffraction (n-XRD) indicate that the homogeneity of the Al–Si eutectic layer produced during the thermal processing, and the associated distortions and strains in the silicon are related to the different PV performances of cells based on both Czochralski and mono-like silicon. The choice of Al paste is therefore crucial for optimizing solar cell performance. Preliminary results are also presented on n-type Czochralski silicon bifacial solar cells, where there is no continuous metallic back-plane, but stacks of silicon dioxide/silicon nitride layers and silver contact lines on both faces. XRDI and n-XRD are shown to be powerful tools for the investigation of the structural perfection and lattice distortions in solar cells, which affect PV performance, from crystal growth through to final solar cell structure.

After a first experiment presented to TRIZ Future Conference 2012 which objective was to teach simultaneously future teachers and students of 2 classes of a technical college, this paper will present a proposal which aims at extending the experiment to a larger group made of 10 colleges, 24 new teachers and about 300 students (compared to 1 college, 6 teachers and 60 students). To resolve the tackled problem (how to train without being trained) a specific pedagogy, named as “knowledge spiral” has been proposed and tested and has brought interesting benefits. The matter is that while the number of people to be trained is enlarged, the number of resources is not extending. To the contrary it is even more restricted, and new constraints have to be considered: • How to apply a pedagogy when the number of students is enlarged, could we used the same pedagogy, and how to adapt it? • How to leverage the “knowledge spiral” with limited resources: especially less time to develop the competences? • How to apply the “knowledge spiral” with geographical separated resources within the same time frame? In these conditions, the new proposal could not be a direct homothetic transformation of the previously proposed one. Thus, a new model, again inspired by the “knowledge spiral” has been developed with the introduction of a fourth level of resources: expert, trained teacher, non-trained teacher, and student. This will, in a certain extent, enlarge the spiral. Another aspect, due to the new constraints, is the use of a generic problem to be solved for all the trained groups, this problem being used both to trained the teachers and proposed to students as a school case study. The case study will emphasizes the different concepts of TRIZ (contradictions, I.F.R., available resources, specific conditions…). This implies the expert to describe both the case, the method to solve it, and also to define the border of the case in order to make it understandable and usable for teachers (without the expert), but without restraining the domain of possible solutions for learners (both teachers and students). To fit these requirements, the proposal was to give teachers the meta-rules of a creative game, these meta-rules enabling the game to be applied in any context. To reach the objectives, the well-known example of TRIZ applied to the rescue of people during the Titanic sinking will be used to develop the creative game. A first session will be directed with teachers, and then the teachers will put it in practice with their students. In order to motivate both the teachers and the students, a kind of competition will be proposed, first between the different teams inside colleges, and then a challenge between the best team of each college. To be relevant this competition will have to fit some pre-defined rules, as nature of problem to be solved, allocated time, team composition, innovative evaluation, and so on. For the evaluation, the already presented “radar” diagram will be used once more.

International audience; Since last year, in France, an official education program includes more than 50 hours of innovation methodology and training mainly based on TRIZ methods! But the problem is that teachers of the classes (sciences and technology for engineers and sustainable development) do not have any training on TRIZ, or will only receive it in the next years... So the contradiction is that teachers have to be taught about TRIZ methods to be able to teach it, but teachers could not be taught on TRIZ methods as there are no time resources to do it. With the aid of an external TRIZ expert, it has been proposed to use as a main resource a team of 6 teachers and the time of course preparation to both teach teachers and develop a new, innovative teaching method. This experiment started this year for 2 classes to inventively teach TRIZ to teachers "in real-time" while students learn it by practicing the innovation methodology and creativity tools through a project. The paper describes the 3-level approach to " develop a new educational method " , to "teach the teachers" and to enable students to learn through a "creativity challenge for innovation". The identified key problems related to this new educational method and the results of this new approach will be presented. As results, one can notice a new way of evaluating where everybody wins (education system, teachers, students), based on contradictory parameters in a "2D radar" highlighting students' inventive abilities. From initial state to Ideal Final result, the paper explores the key success factors, the next steps and the set of problems linked to the implied actors: teachers and students, and also the educational system. The originality of the approach is that typical solutions used in learning with industries have been applied in the educational system, whereas it is traditionally the opposite…

In this paper, a first evaluation of the compatibility between thermal donor-doped Czochralski silicon and the hydrogenated amorphous Silicon/crystalline Silicon heterojunction technology, is presented. The wafers resistivity was adjusted thanks to the controlled thermal donors generation through 450 °C anneals of calculated durations, following a model detailed in this paper. Minority carrier lifetimes higher than 2 milliseconds, matching the requirements of the heterojunction technology used, were demonstrated. The solar cells were manufactured and efficiencies comparable to cells based on “high quality” Float-Zone substrates were obtained. The stability of the solar cells performances under illumination and temperature was also assessed, and revealed no degradation of the bulk quality even after prolonged illumination.

Passivating the contacts of crystalline silicon (c-Si) solar cells with a poly-crystalline silicon (poly-Si) layer on top of a thin silicon oxide (SiOx) is currently sparking interest for reducing recombination at the interface between the metal electrode and the c-Si substrate. Hole-selective poly-Si/SiOx structures could be particularly relevant to passivate the rear side of mass-produced p-type c-Si solar cells (i.e. PERC solar cells). In this study, we elaborate on the optimization of a hole-selective passivating structure consisting of a boron-doped poly-Si layer on top of a chemically grown thin SiOx. The poly-Si layer is prepared by Plasma Enhanced Chemical Vapor Deposition, which enables single-side deposition. However, if not optimized, this deposition technique leads to degradation of the poly-Si layer through a “blistering” phenomenon due to high hydrogen incorporation in the layer. To tackle this, a study of the interplay between process parameters and blistering is undertaken in order to obtain highly passivating and blister-free poly-Si/SiOx structures. By addition of a hydrogenation step, the implied open circuit voltage (iVoc) provided by the structure is further improved, leading to a maximum value of 734 mV demonstrated on symmetrical samples made from large area wafers. We also conduct a Conductive-Atomic Force Microscopy (C-AFM) study with the aim of investigating the pinholes formation in the SiOx interfacial layer that could explain the transport of free charge carriers within the poly-Si/SiOx structure. We show that the current levels detected by C-AFM are affected by an oxide layer that grows at the poly-Si top surface. We also demonstrate that conductive spots detected by C-AFM are not likely to mirror conductive pinholes within the SiOx layer but are rather linked to the poly-Si layer.

The present study focuses on the kinetics of the boron-oxygen defect activation in solar cells fabricated from two Czochralski silicon ingots having different compositional properties (particularly various carbon and germanium contents). We show first that the difference between the experimental and the expected time constants associated with the degradation of the cells performances under illumination due to the boron-oxygen activation is higher in the last solidified part of the ingots. Secondly at such locations a pronounced slowing down of the long-term kinetics is observed. Possible explanations are proposed and discussed among which the segregation of some impurities which could interact with oxygen or oxygen dimers. Particularly a clear correlation is highlighted between the carbon content and the amplitude of this slowing down. Eventually this work shows that the experimental conditions generally used for evaluating the amplitude of the light-induced degradation effects have to be reconsidered.

International audience; In the present work, a recrystallization process of sintered silicon wafers was studied to produce photovoltaic solar cells. The recrystallization step is carried out by Zone Melting Recrystallization (ZMR) or Full Wafer Recrystallization (FWR). Structural analysis and impurity content of the processed material are presented. Electrical characterization shows that mobility reaches values of 150 and 250 cm(2) V-1 s(-1) in samples recrystallized by FWR and ZMR with P-type doping of 5 x 10(16) and 3 x 10(17) at/cm(3). The lifetime reaches values around 1 mu s. After solar cell fabrication, a conversion efficiency of 8.9% is obtained by using a simplified process without texturing

The hard breakdown behaviors of boron–phosphorus compensated p-type and n-type Czochralski silicon solar cells were studied as functions of the type of conductivity, the net doping concentration and the temperature. We showed as expected from previous studies that the hard breakdown was governed by avalanche mechanisms (impact ionization) and that for a given net doping concentration the hard breakdown voltage was almost the same for both p-type and n-type solar cells, despite the different reported values for the electron and hole impact ionization coefficients. The studied compensated materials offered the opportunity to determine the hard breakdown voltages for samples with the same net doping concentration but different total amount of doping species. However no major effects of the dopant compensation were observed, the experimental data being described by the empirical expressions used for uncompensated silicon samples.

International audience; What roles do public poetry performances (i.e., "readings") play in contemporary fields of poetry production? Drawing from extensive ethnographic, survey, and interview data gathered in Paris, New York, and Toronto, we explore the social dynamics of readings in order to understand better how these public and social gatherings contribute to poetry economies and careers. While differences exist between the locations for our research, the similarities are striking: we find that readings are crucial to poetry economies because they foster and maintain distribution networks for contemporary poetry in a global marketplace that tends to squeeze out forms of art that lack broad commercial appeal. We also find , across these locations, that readings are used in different ways by poets at different stages of career (i.e., unestablished, established and well-established) and by poets operating in different genres (i.e., those writing "for the stage" versus those writing "for the page"). Finally, we emphasize that readings provide an important space in which poets and others (e.g., booksellers, publishers) navigate the difficulties of making art while dealing with the necessities of money.

This letter focuses on the variation of the Hall majority carrier mobility with the dopant compensation level in purely Boron-doped Czochralski grown silicon single crystals. Compensation was varied continuously at the sample scale via a step by step activation of the oxygen-based thermal donors. At room temperature, we show a strong drop in mobility for high compensation levels in both p- and n-type Si. Mobility models taking into account carrier scattering on ionized impurities and phonons could not reproduce this drop. We conclude that a specific effect of compensation must be taken into account to explain the observed behaviour. We qualitatively discuss physical mechanisms susceptible to reduce mobility in highly compensated Si.

In an array of problem solving methods, one can traditionally distinguish two kinds of problems: one is a problem that has solutions in a search space and the other is a problem that does not have solutions in a given space. The later problem so called solutionless problem or inventive problem requires an inventive approach to reformulate the problem and dialectical thinking brings benefits in the process. The framework used to formulate problems in a dialectical approach is contradiction. Identification of contradictions plays an important role in distinguishing solutionless problems: a contradiction exists when no solution can be found, and a solution exists when no contradiction can be found. In this article, the inadequacy of existing frameworks in satisfying this requirement is demonstrated and a framework that fits this requirement is proposed.

The effects of boron diffusion were investigated on electronic grade n-type single- and multicrystalline silicon wafers for solar cells application. Doped p+-layers were formed using specific spin-on dopant (SOD) source annealed in a tube furnace. Homogeneous diffused layers with sheet resistance values of 70 Ω/sq were achieved on large area silicon wafers. Bulk electrical properties were investigated measuring the effective carrier lifetime after the diffusion step. A significant degradation of the bulk electrical properties was observed using the SOD technique. Unlike for the single-crystalline silicon, it was determined that this effect was not due to an interstitial iron contamination originating from the SOD, but rather by the thermal degradation of the material. Boron diffusion was followed by a phosphorous diffusion sequence, necessary in the fabrication process for the formation of the back surface field. This additional step leads to an improvement of effective lifetime values due to an efficient gettering of the impurities. Finally, bulk carrier lifetimes from 100 μs to over 300 μs were deduced on n-type multicrystalline silicon after boron and phosphorus diffusion. This underlines the potential of this material for photovoltaic application and its stability after high temperature treatments provided that a gettering step is included after the boron diffusion step.

PURPOSE: Event-related potentials (ERPs) studies in human subjects have shown inter-individual response variations, probably linked to anatomical and functional brain disparities. The present study was conducted to compare the results obtained by a standard grand-average method and a single subject analysis of VEPs to faces. MATERIAL AND METHOD: Fifty-eight channel ERPs (analysis time: 1,024 ms) were recorded in 13 normal volunteers during gender or familiarity judgements on unknown and known faces, as well as on a control task using meaningless patterns. Data were then submitted to individual and group averages. RESULTS AND CONCLUSION: Three activities were identified by both procedures: a P1/N1 complex, a vertex positive potential (P2 or VPP) associated with a temporal negativity, and a N2 negativity. These peaks displayed a marked inter-individual topographical variability. Regarding the outcome of statistical analyses, a certain number of differences were found: on P1, in which individual analyses revealed a strong effect of experimental conditions, while the grand-average method did not; on VPP, in which grand-average analyses suggested an interaction between experimental conditions, face familiarity and cerebral lateralization, while individual analyses did not; and on N2, in which grand-average data showed a clear lateralization effect, while individual analyses did not. A P3 component (Pz, 250 ms) was also defined in grand-average data, but could not be clearly described in individual data. Statistical analyses on this P3 component were thus only performed on group data and revealed a right lateralization and an interaction between face familiarity and experimental conditions. These findings confirmed the existence of a marked topographical variability of ERPs to face and, therefore, question the validity of grand-average studies. Moreover, these results suggest a better efficiency of individual analyses for studying short and middle-latency peaks, while grand-averages appear to be better suited for studying late components.