Yoann Zaouter
email: yzaouter@amplitude-systemes.com

Louis Daniault

Marc Hanna

Dimitris N Papadopoulos

Franck Morin

Clemens Hönninger

Eric Mottay

Frédéric Druon

Patrick Georges

Passive coherent combination of two ultrafast rod type fiber chirped pulse amplifiers

Using passive coherent beam combining of two ultrafast fiber amplifiers, we demonstrate the generation of high temporal quality 300 fs and 650 µJ pulses i.e. 60 W of average power at a repetition rate of 92 kHz. Furthermore at 2 MHz of repetition rate a record coherent combining average power of 135 W before and 105 W after compression is measured. A combining efficiency higher than 90% is maintained over the whole range of output powers and repetition rates investigated demonstrating the efficiency and robustness of the passive combining technique. The measured pulse-to-pulse relative power fluctuation at high energy is 2%, indicating that the system is essentially immune to environmental phase noise. We believe the passive combining method to be an attractive approach for compact multi-GW peak power femtosecond fiber-based sources.

The peak power obtained from high repetition rate ytterbium-doped ultrafast fiber amplifiers has grown extremely rapidly during the last decade to reach the multi-GW level owing to the development of very large mode area fiber designs [1]. To further scale this peak power and obtain compact and efficient high repetition rate high energy sources, the coherent combination of several such femtosecond fiber lasers has recently been demonstrated. Early demonstrations have involved an active control of the relative phase between two fiber chirped-pulse amplifiers (FCPA). A first experiment used the measurement of the polarization state of the combined beam, and a feedback on a piezo-mounted mirror located in one amplifying arm [2]. The same group scaled up the performances to a record energy of 3 mJ [3]. A second demonstration was based on of the frequency tagging technique [4], while the feedback is done through an integrated fiber-coupled LiNbO3 phase modulator [5]. Both these implementations have demonstrated feedback bandwidths in the 1-10 kHz range. They require complex opto-electronic feedback schemes, and the stability of such sources in noisy environments will depend on the sophistication of the feedback loop. Recently, we proposed an alternative technique to achieve coherent combining of two amplifiers in a passive architecture involving a Sagnac interferometer [6]. The phase stability of this simple scheme is inherently guaranteed by the fact that both combined beams travel along the exact same optical path in a counter propagating geometry. Our proof-of-principle experiment showed that the passive technique is compatible with high nonlinearity levels, and that the limiting factor is the ability to maintain the symmetry of both paths. In this Letter, we use the passive combining architecture and rod-type fiber amplifiers to generate high temporal quality 300 fs pulses with 650 µJ of energy per pulse at a repetition rate of 92 kHz. This corresponds to an average power of 60 W, and a peak power in excess of 2 GW, demonstrating the potential of the technique in a high performance fiber system. To maintain a good temporal pulse quality simultaneously with a high energy level, we implement a moderately nonlinear FCPA in which the impact of nonlinearities is partially compensated by the dispersion mismatch of the stretcher and compressor units [7]. Furthermore, the two amplifiers that we intend to coherently combine are built within a Sagnac interferometer that is seeded, through an optical isolator, by a frontend. This frontend is composed of a passively mode-locked ultrafast oscillator, a pulse picker, a pulse stretcher, and a single-mode fiber pre-amplifier. The oscillator generates pulses at the central wavelength of 1030 nm. The full width at half maximum of the spectrum is 9 nm and sustains pulse durations below 200 fs. The repetition rate of the oscillator of ~25 MHz is divided by an acousto-optic modulator pulse picker and can be varied from 92 kHz to 25 MHz. Sufficient pulse stretching is then applied to the pulses in order to mitigate the impact of nonlinearities in the power amplifiers. The stretching ratio is designed to preserve a pulse duration of ~600 ps after the power amplifiers when operated at maximum gain. A single mode fiber amplifier is used to boost the average power to about 100 mW, which is sufficient to seed both power amplifiers. An optical isolator is placed after the frontend to prevent any optical feedbacks coming from the power amplifiers. It is also used to separate the combined and the uncombined outputs of our passively coherently combined amplification scheme. The beam is split by a polarizer and each secondary beam seeds a power amplifier (denoted as Amp #1 and Amp #2, see Figure 1) made of state-of-the art ytterbium-doped rodtype photonic crystal fibers. These rigid fibers are kept straight in un-cooled V-groove holders and are optically pumped by 976 nm fiber coupled pump diodes. The mode field diameter of the fibers is 85 µm, the pump cladding diameter is 285 µm and their length of 1 m ensures sufficient pump absorption and optical efficiency [8]. The outputs of each amplifier are connected to each other to close the Sagnac interferometer. Therefore, after the polarizer, the light propagating clockwise is first preamplified in Amp #1 and then amplified in Amp #2 while the light travelling counterclockwise is first pre-amplified in Amp #2 before reaching its maximum power / energy at the output of Amp #1. Both beams are then recombined on the polarizer, with linear polarizations orthogonal to each other. If both beams are in-phase, they form a combined output beam propagating back to the isolator with a linear polarization state at an angle of 45 °. This beam is therefore transmitted back through the rotator and ejected by the polarizer located at the input of the isolator. The uncombined part of the beam is removed by the polarizer located at the output of the isolator. Measurement of the average power at both outputs allows us to compute the combination efficiency defined as the ratio between the combined power and the total power. The path length for one round trip in the Sagnac interferometer is 5.5 m, making this setup immune to all phase noises with frequency contents below 27 MHz. This large bandwidth essentially removes all environmental sources of noise such as acoustic and thermal fluctuations of the relative phase. To highlight the robustness of this architecture with respect to phase noise, we compare the pulse-to-pulse relative power fluctuation of the frontend to the one measured at the output at maximum energy. This pulse-to-pulse stability is 1.1% for the frontend, and reaches 2% at the maximum compressed energy. This very small decrease of the pulse-to-pulse stability for a nonlinear FCPA, built on an uncovered breadboard, clearly indicates that phase noise has very little impact, if any, on the global coherent combination stability. This is of particular importance if lasers using our passive coherent combination architecture are to be used in harsh environments or if the pulse-to-pulse stability is of particular importance for the targeted scientific or industrial applications. Finally, the coherently combined beam is sent through a compressor optimized to get the highest possible peak power. The high efficiency gratings used allow for only 21 % loss in the compressor. The passive coherent combination setup described above is first aligned at low power and low energy in order to obtain the best possible degree of combination related to spatial aspects such as beam profile and wavefront mismatch. We found out that slight differences in the rod type fibers end-facet preparation is currently the main limitation to the combination efficiency, with a maximum value of ~95%. The pulse picker is then set to downcounter the repetition rate of the frontend to 92 kHz. Figure 2 shows the amplifier characteristics at this repetition rate with the combined and uncombined average powers measured at the output ports of the isolator. At the maximum total pump power of 160 W, we reach 75 W of passively coherently combined power, i.e. 815 µJ, with a slope efficiency close to 60 %. It is noticeable that despite the accumulation of a large quantity of nonlinear phase shifts in the amplifiers (estimated to be ~7 rad per roundtrip), the combining efficiency decreases by less than 3.5 %. We investigated the origin of this loss and found out that nonlinearity mismatch between the two circulating directions is the main source of drop in combining efficiency. Indeed, at 75 W and 2 MHz of repetition rate the rejected uncombined power is only 5W, resulting in a combining efficiency close to 94 %. At even higher average power we see another roll off in efficiency that originates from a worst spatial overlap of the two beams. Nevertheless, for 270W of total pump power at 2 MHz of repetition rate, we reached 135 W of coherently combined power with a passive coherent combining efficiency of 91.5 %. The compressed average power of 105 W is to our knowledge the highest average power ever generated by any active or passive coherently combined ultrashort amplifiers. We now investigate the compressibility of the amplified pulses at maximum energy. At 92 kHz, the maximum average power measured after the compressor is 60 W (76 W before) i.e. 650 µJ of energy per pulse. Figure 2 shows the autocorrelation traces acquired with an intensity autocorrelator and independently measured with a second-harmonic generation frequency-resolved optical gating apparatus (FROG). These autocorrelations can hardly be differentiated and exhibit a FWHM duration of 400 fs. Figure 2 also shows the retrieved temporal profile of the pulse from the FROG measurement. Its duration is 300 fs, corresponding to a time-bandwitdh product (TBP) of 0.75. The very good temporal quality obtained allows us to measure a peak power in excess of 2 GW. Figure 3 compares the input spectrum delivered by the frontend and the spectrum of the amplified pulses at maximum energy. The spectral bandwidth is well preserved throughout the amplification and compression optics. We observe a significant steepening on the long wavelength side of the spectrum at high energy due to gain saturation of the amplifiers that tends to amplify more the leading edge of the pulses, i.e. the long wavelengths, which shifts the maximum of the spectrum to 1035 nm. The spectral bandwidth measured at maximum compressed energy is ~8.5 nm and supports transform-limited pulses of 240 fs duration (corresponding TBP ~ 0.58). In conclusion, we demonstrate a significant performance scaling of the passive coherent combining concept introduced in Ref. [5] in a moderately nonlinear FCPA. The use of state-of-the-art ytterbium-doped rod-type photonic crystal fibers permits to generate ultrashort pulses with 650 µJ of energy per pulse together with a measured duration of 300 fs at a repetition rate of 92 kHz. The very good temporal quality of the recompressed pulses allows obtaining more than 2 GW of peak power. At the higher repetition rate of 2 MHz, 135 W of passively coherently combined average power (limited by the available pump average power) resulting in 105 W of compressed average power has been measured which is to our knowledge the highest average power ever reported from an ultrafast coherent combining system. All the performances reported in this Letter have been obtained with combination efficiencies over 91 %. Moreover, a careful preparation of the end-facets of the fibers together with a better thermo-mechanical management could help increasing this value. The authors strongly believe that this concept of amplification has the potential to generate more than 10 GW. This could be directly obtained with an additional post compression module base on a hollow core fiber or by increasing the stretching ratio to the level of Ref. [1]. The average power of these fiber systems could also be scaled to 1.5 kW by using adequate fiber designs such as those demonstrated in Ref. [9], with pulse duration well below 500 fs in all cases.

Figure 1 :

 1 Figure 1: (Color online) Experimental setup Figure 1 shows the experimental setup used in our work.To maintain a good temporal pulse quality simultaneously with a high energy level, we implement a moderately nonlinear FCPA in which the impact of nonlinearities is partially compensated by the dispersion mismatch of the stretcher and compressor units[7]. Furthermore, the two amplifiers that we intend to coherently combine are built within a Sagnac interferometer that is seeded, through an optical isolator, by a frontend. This frontend is composed of a passively mode-locked ultrafast oscillator, a pulse picker, a pulse stretcher, and a single-mode fiber pre-amplifier. The oscillator generates pulses at the central wavelength of 1030 nm. The full width at half maximum of the spectrum is 9 nm and sustains pulse durations below 200 fs. The repetition rate of the oscillator of ~25 MHz is divided by an acousto-optic modulator pulse picker and can be varied

Figure 2 :

 2 Figure 2: (Color online) Left scale: output powers of the amplifier as a function of pump power at a repetition rate of 92 kHz. Right scale: combining efficiency as a function of pump power. Inset: beam profile taken at maximum energy at the output of the system.

Figure 3 :

 3 Figure 3: (Color online) (a) Autocorrelation traces measured at 650 µJ (blue) with an independent autocorrelator and (red) from a FROG measurement. (b) Retrieved temporal profile of the pulse from the FROG measurement (Error 27.10 -4 on a 256 x 256 grid).

Figure 4 :

 4 Figure 4: (Color online) Optical spectrum measured (blue) at the output of the frontend and (red) after compression at maximum energy.


Alaric Bourgoin
email: alaric.bourgoin@mines-paristech.fr

Fabian Muniesa
email: fabian.muniesa@mines-paristech.fr

Making a consultancy slideshow "rock solid": a study of pragmatic efficacy

The paper examines the pragmatic efficacy of a paradigmatic representational device used in the work of management consulting: the diagrammatic presentation of managerial problems in a consultancy slideshow. We present an ethnographic analysis of a consultancy mission, focusing on the moments in which presentation is crafted, altered and discussed before reaching a stage of relative felicity. We analyze the conditions for this felicity as they are made explicit through the consultants' ordinary work. We found that consultants manage three types of constrains when producing the representational device:

(1) to create an appropriate effect on the target, (2) to be faithful to the "reality" of the situation and (3) to maintain an internal coherence of the representation. We further discuss these three aspects in the light of a pragmatist approach.

Introduction

What follows is an examination of the type of reality that is conveyed through one paradigmatic device within the practice of management consulting: the consultancy slideshow. We interrogate the pragmatic, performative features of a demonstrative diagram that consultants put forward in order to describe the problem of the client organization. By investigating the elaboration and use of a slideshow (the electronic visual document also often referred to as a "PowerPoint presentation" in reference to the Microsoft software) in the context of a consultancy assignment, we show that consultants manage several constraints to elaborate a representation that is finally coined as "rock solid", i.e. expected to perform a state of the world that is suitable for the client to take actions. This specific order is materialized in a document that can be pointed at, recalled and which stabilizes a reality which is considered as appropriate by the relevant parties.

It has been argued that recent literature on management consulting extensively draws from sociological neoinstitutionalism, that is "on the argument that it is belief in the efficiency of particular practices or solutions, rather than any proven efficiency, that determines or influences economic action" (Armbrüster 2006, p. 7). In this respect, the cultural features of management consulting have been extensively investigated through a rather critical angle (see, for example, [START_REF] Clark | Critical Consulting: New Perspectives on the Management Advice Industry[END_REF]. Consultants are depicted as outsiders relying on both non-codified [START_REF] Alvesson | Organizations as rhetoric: knowledge-intensive firms and the struggle with ambiguity[END_REF]) and fashionable knowledge [START_REF] Abrahamson | Management fashion[END_REF], evolving in ambiguous environments "where clarifying means-ends relationships or exercising qualified judgment becomes seriously reduced" [START_REF] Alvesson | Organizations as rhetoric: knowledge-intensive firms and the struggle with ambiguity[END_REF](Alvesson , p. 1001). Their concern is to "persuade" clients of their value to gain legitimacy and ensure further selling [START_REF] Clark | Managing Consultants: Consultancy as the Management of Impressions[END_REF][START_REF] Clark | The management guru as organizational witchdoctor[END_REF][START_REF] Sturdy | The consultancy process: an insecure business[END_REF]. Storytelling, drama, authoritative arguments, packaged instruments, branding, managerial myths are considered as many "tactics" used by consultants to manipulate clients' perception of what is real, efficient, valuable, problematic and so on. Fincham considers, for example, that consultants demonstrate value to their clients "through what is latent in [their] discourse: its range of rhetorical techniques, ways of controlling the image that clients receive, the definition of client problems" (1999, p. 336). If visual rhetoric is the theme of this paper, however, we do not venture into such critical path, except for the purpose of noticing concern on how reality is expressed, depicted, imaged or imagined in consultancy accounts, and on how reality responds to these images and depictions.

Little attention has been given in this and comparable literatures to material aspects of the consulting practice, a practice which is mostly seen as an intangible service [START_REF] Clark | Managing Consultants: Consultancy as the Management of Impressions[END_REF].

A notable exception would be the work of Irene Skovgaard [START_REF] Smith | Materializing the organization: the role of consultants in the processes of objectification[END_REF] who points the crucial role of consultants in "materializing the organization" (p. 1). According to this author, "an important part of consulting activity is to objectify problems and what is going on in the organization" (p. 1), consultants being agents "positioned by internal actors as truth tellers and pen holders" (p. 2). Indeed, when observing consultants in vivo and in situ one can realize their job is foremost a "writing job" where the production of "intellectual technologies" [START_REF] Latour | Science in Action: How to Follow Scientists and Engineers through Society[END_REF], 2005[START_REF] Miller | Governing economic life[END_REF] in the form of reports, memos, minutes, reviews, presentations, charts and so forth represents a significant workload. These material inscriptions have the virtue to "show while finalizing" consultants' work [START_REF] Goff | Pratiques et identités professionnelles dans le conseil en management en France: entre ethos du service au client et pression du 'up or out[END_REF] and clients ought to bear in hands concrete "deliverables" at the end of almost any assignment. Consulting techniques are developed as proprietary systems [START_REF] Fincham | The consultant-client relationship: critical perspectives on the management of organizational change[END_REF]) so as to be transferred or sold to clients in tangible forms.

Microsoft PowerPoint software has become today a favored tool to create these inscriptions and to mediate consulting advice. Displaying an expert use of PowerPoint has itself become a crucial skill for consultants [START_REF] Kaplan | Strategy and PowerPoint: an inquiry into the epistemic culture and machinery of strategy making[END_REF]. A growing literature puts forward the role played by PowerPoint in the creation of a pervasive business cognitive style that cannot be limited to its well-known shortcomings [START_REF] Gabriel | Against the tyranny of PowerPoint: technology-in-use and technology abuse[END_REF], Stark and Paravel 2010[START_REF] Kaplan | Strategy and PowerPoint: an inquiry into the epistemic culture and machinery of strategy making[END_REF][START_REF] Yates | The PowerPoint presentation and its corollaries: how genres shape communicative action in organizations[END_REF][START_REF] Knoblauch | The performance of knowledge: pointing and knowledge in Powerpoint Presentations[END_REF][START_REF] Beaudoin | PowerPoint: le lit de Procuste revisité[END_REF][START_REF] Gaglio | Faire des présentations, c'est travailler, mais comment? Diapositives numériques et chaîne d'activités dans des services marketing[END_REF]Doganova and Eyquen-Renault 2009). For example, in her in-depth study of PowerPoint use in the making of strategy, [START_REF] Kaplan | Strategy and PowerPoint: an inquiry into the epistemic culture and machinery of strategy making[END_REF] found "that PowerPoint mediated two discursive practices: collaborative efforts to negotiate meaning and cartographic efforts to adjudicate interests" (p. 327). Strategy is about industry structures, product differentiation, operational performance, resource allocation, and so on, but it is also about using visual and discursive technology to provide materiality to unclear ideas and create spaces for negotiation of meaning. Giving insight on how both elements intermingle in practice, through the case of a diagnosis assignment, is the purpose of this paper.

Thus, this study connects with perspectives inspired by Actor-Network Theory which takes tools of representation as entry points for the analysis of organized actions (e.g. Law and Hassard 1999, Czarniawska and Hernes 2005, Callon, Millo and Muniesa 2007). In this vein, [START_REF] Cooren | Textual agency: how texts do things in organizational settings[END_REF] examines the agency of written, oral and iconic texts in organization.

According to this author, "signs, memos and contracts display a form of agency by doing things that humans alone could not do. Created by human beings, these texts participate in the channeling of behavior, constitute and stabilize organizational pathways, and broadcast information/orders" (Cooren 2004, p. 388; see also Cooren, Taylor andVan Every 2006, Bencherki and[START_REF] Bencherki | Having to be: the possessive constitution of organization[END_REF]. The performative aspect of texts and visuals is also underlined by recent works which explore the role and effect of business imagery in organization, investigating rhetoric, visual and methodological aspects [START_REF] Quattrone | Books to be practiced: memory, the power of the visual, and the success of accounting[END_REF]. Indeed, "imagining business" (Puyou, Quattrone, McLean and Thrift 2012) could be considered as one of consultants' main functional task. But the very process by which this imagining is done still lacks in-depth analysis. By focusing on this aspect, this paper also goes along the lines of ethnographic and longitudinal studies of practice that present management consulting in its complex, varied and dynamic form [START_REF] Sturdy | Management consultancy: boundaries and knowledge in action[END_REF][START_REF] Whittle | From flexibility to work-life balance: exploring the changing discourses of management consultants[END_REF], drifting away from a common opposition in academic literature between critical and functionalist approaches [START_REF] Whittle | The paradoxical repertoires of management consultancy[END_REF][START_REF] Armbrüster | The Economics and Sociology of Management Consulting[END_REF].

Our contribution concerns one particular problem of management consulting communication that we call the problem of pragmatic efficacy. In the case set out to be examined here, we observe that the consultancy diagram stands as a description of a firm's problems and of sound directions for solution, but that its elaboration is mostly characterized by concerns about the layout, the visuals, the keywords, and the smack of seriousness. Is the diagram true? Or is it a trick, a decoy? We attempt at avoiding this line of interrogation, and rely instead on a pragmatist approach in the sense that we focus on what the slideshow does rather than on how it represents and external reality. We follow a diagram, through ethnographic materials on one consultancy mission, from a state of artifact to a state of relative felicity (i.e., it works).

In the following section, we sketch out our approach to the problem of pragmatic efficacy. In section 3, we present the research methodology and Effictio Consulting, the company in which field work was conducted. In section 4 and 5 we present our empirical materials, which are discussed in section 6.

A pragmatic reading of symbolic efficacy

Considering management consulting in the terms of the anthropology of remedial rituals is now perhaps a lieu commun. The consultant as shaman or witchdoctor stands as a legitimate resource in the repertoire of business ethnography and also in the ordinary vocabulary of consultancy proper [START_REF] Woodworth | Witch doctors, messianics, sorcerers, and OD consultants: parallels and paradigms[END_REF]Nelson 1979, Clark and[START_REF] Clark | The management guru as organizational witchdoctor[END_REF].

Notions of incantation, storytelling and the manipulation of symbols populate both the critique of managerial culture and its ordinary practice. But it is interesting to observe that one of the classical texts in the anthropology of remedial rituals is precisely one that tries to clarify more drastically the problem of what we call pragmatic efficacy.

In his classical study of "symbolic efficacy" (i.e. of the efficacy of symbols, their practical effectiveness) in shamanistic cure, Claude Lévi-Strauss develops an understanding of incantation as a practical instrument for therapy [START_REF] Lévi-Strauss | L'efficacité symbolique[END_REF]. Chants are first said to be a "psychological manipulation of the ill organ" (ibid., p. 12, our translation), but then a matter of "introducing a series of events of which the body and the internal organs constitute the stage" (p. 13). Very much like the psychoanalytical cure, Lévi-Strauss writes, the shamanistic cure is about "provoking an experience" (p. 21) and therefore requires an enlargement and a positive understanding of the notion of manipulation: "it is sometimes about the manipulation of ideas, sometimes about the manipulation of organs, but in all cases through symbols, that is, through significant equivalents of what is signified, pertaining to a different order of reality" (p. 22). Lévi-Strauss refers there to Marguerite Sechehaye's psychoanalytic method of symbolic realization. As Lévi-Strauss makes clear, efficacious symbolic manipulation is not about lying to the patient. It is about provoking an event in which the organs are mobilized through their participation in a simulacrumbut a simulacrum that effectuates reality.

Calling Lévi-Strauss a pragmatist can be quite at odds with the legacy of structuralism.

But, as [START_REF] Hennion | La question de la tonalité, retour sur le partage nature-culture: relire Lévi-Strauss avec des lunettes pragmatistes?[END_REF] has rightly suggested, the work of Lévi-Strauss contains a series of intuitions that gain in strength if considered from a pragmatist angle. The idea of "symbolic efficacy" is indeed quite compatible with the notion the empirical action of the sign developed by pragmatist philosopher Charles Sanders Peirce in his theory of signification, also with Austin's notion of the performative utterance or Searle's speech acts theory (Hoopes 1991[START_REF] Searle | Speech Acts: An Essay in the Philosophy of Language[END_REF][START_REF] Austin | How to Do Things with Words[END_REF]. The chants and invocations are performative insofar as they refer to states of affair that are provoked by the act of statement, or are meant to be so with greater or lesser success. Success, indeed, or felicity (as John Austin would have it) depends on a series of arrangements that are not yet fully described in Lévi-Strauss' account but that are likely to be connected to the "manipulations" undergone within the situation and that could be illuminated by ethnographic investigation.

When translated into our subject matter, this pragmatist take on symbolic efficacy allows us to tackle how well the consultancy slideshow diagram refers to the states of affair it contributes to constitute. Our hypothesis, thus, is that the felicity of this referential process depends more on the crafts of the consultants in the process of manipulating symbols than on any natural adequacy of their designation apparatus to the object of consultancy. The idea of manipulation requires being taken here in its most natural sense, not as an indication of some kind of deceitfulness: it means to handle with the hands, to arrange and to assemble. That said, something can be handled more or less felicitously, and what we explore in this research are precisely the conditions in which the referential process undertaken by the consultants do hold together. In our concluding discussion below, we isolate three constraints that the production of a consultancy diagrammatic presentation undergo (effect, accuracy and layout) and we connect them to a pragmatist viewpoint on symbolic efficacy (and, more concretely, to Peirce's theory of signification).

Methodology and context

In this article, we draw from an ethnographic study conducted at Effictio Consulting (pseudonym), a company based in France that employs 150 consultants and operates in a variety of sectors, from banking to healthcare. Empirical materials were gathered by the first co-author during eight months of active observation, while he was himself working as a consultant in 2010. Comprehensive access to organizational activities was granted by regular, professional participation to consultancy assignments and other day-to-day activities. The analyzed materials were gathered through a range of methods: document collection (including emails, notes and reports), participation in meetings and conversations, and field notes written on a continuous basis.

Our focus is on one single consultancy mission. The assignment concerned Aeger Hospital (pseudonym), a healthcare institution resulting from the merger of two smaller hospitals. Effictio Consulting had to carry a mission of analysis and restructuration of the support functions of the organization (the medical departments were out of the scope of the analysis), these tasks being formulated as follows in the assignment letter: "Aeger Hospital is carrying out a reflection on its strategic positioning [...]. Three major objectives are set: to exceed a critical size [...], to develop new activities [...], to better take into account the legal environment [...]. To achieve these goals, it is necessary to align the administrative organization of the [new hospital] with its strategy and to provide all the necessary means for the top management team to succeed. In this context, Effictio Consulting's mission is to analyze the current organization, to evaluate the extent to which the organization is adapted to the challenges of the future, to define an administrative target and to suggest steps towards its achievement." (Field document, "Assignment Letter", October 2009, our translation)

As one can see from this excerpt, the client does not give precise indications of what is expected in terms of outcomes for the assignment. The situation reminds of [START_REF] Schein | Process Consultation: Its Role in Organizational Development[END_REF] "doctor-patient" model of consulting in which the client barely feels a need for change, but relies on the consultant to precisely define a target and the means to reach it. In this type of mission, the "diagnosis phase" is very important. The diagnosis is in itself a form of intervention that modifies the characteristics of the observed system (ibid.). Spotting the problem (the "real" problem) and pointing it to the client in a demonstrative manner, so it can be acknowledged and taken into account, is halfway to recovery.

The assignment involved two consultants: a junior consultant that we call Tony (pseudonym, one of the co-authors) and a senior consultant, Camille (also a pseudonym). 1The team was led by a Partner at Effictio Consulting, who stepped in sporadically for formal presentations.

The mission had two particularities. First, the post-merger situation required major organizational adjustments which brought about strong political tensions among the hospital directors. Second, the restructuration undertaken by Effictio Consulting had to align with a strategic planning led at the same time by another consultant, Mister K (pseudonym), who had a long track record of past collaborations with Aeger and benefitted from the CEO's trust.

Camille expected to interact with him during the assignment, which she felt put her in a delicate situation given that he was a competitor.

The assignment included four phases. In the first phase, the consultants had to gather and analyze information, either through interviews at Aeger Hospital or other methods. The second one consisted in delivering a report presenting an "analysis of the current state of affairs" at Aeger, a form of diagnosis of the situation as observed by the consultants. Based on this inventory, a third phase followed in which consultants laid out steps to solve observed problems and reach targets. Finally, the fourth phase was to implement a plan for change according to the consultants' advised course of action. Gathering data took the consultants about three months, plus one month to draft the analysis of the situation: a 120-pages PowerPoint report, accompanied with several digest presentations.

Narrowing down to the slideshow

We focus in this paper on the second phase of the assignment, the production of a situation analysis report. This was considered "decisive" by the client and represented most of the workload. The assignment letter mentioned that the solution-seeking phase would only start after a full validation of this first report, and that remedies would be co-produced by the consultants and the Board of Aeger Hospital during a special-purpose seminar. The report was the result of fifty semi-structured interviews with insiders, benchmarking with executive managers of three other hospitals to confront the findings, and in-depth analysis of best practices in operational management of healthcare institutions through literature review and data mining. When the consultants started to draft the report, they had reached a consensus on what the main dysfunctions were. The lack of efficiency of patient administrative management processes (which go from admission to billing, including medical coding and relations with health insurance companies) was identified as a core problem. Flaws in the human resources department (payroll management, hiring, and so on) and overall lack of governance were also diagnosed. The aim at this stage was therefore to find a way to organize and formulate an analysis that was mostly already made. Camille actually wanted to reuse the documents that had been produced along the first phase of the assignment: "We have to be exhaustive, using all the information we obtained during the interviews. We also need to capitalize on the minutes that were already approved. There is a formal constraint: all needs to be very clear, adjustable, a PowerPoint presentation will do." (Field notes, December 2009, our translation)

The slideshow we analyze in-depth held a specific position in a report that required important preparatory work. The consultants decided to begin with a "broad frame of analysis" and to submit it to the client for comments ("testing it", as consultants said) before going any further in the writing process. The report framework had to revolve around two main points: "transversal dysfunctions analysis" and "department-by-department analysis of dysfunctions". In the "transversal dysfunctions" section, problems were to be presented in a general fashion without assigning responsibilities or going too far in details. The section "department-by-department analysis of dysfunctions" would be more detailed and, according to Camille, "more stigmatizing because pointing direct responsibility" (Field notes, December 2009). As a result, the first type of content was to be forwarded to top management, and widely communicated upon. The second type would only be accessible as a whole to the CEO and each section would be sent to the department director it concerns. The formulation of the "transversal dysfunctions" and its connection, or not, to responsibilities at each department's level remained a strong concern throughout the consultancy work, as expressed by Camille in an informal conversation: "I'm still raking my brain, trying to come up with a way to present the transversal aspects. […] I was thinking that perhaps we could point out crossdepartment aspects talking about dysfunctions where departments interact ["dysfonctions aux interfaces" in French] in the administrative management of the patient. The objective would then be to spot problems about the perimeter of each department." (Field notes, December 2009, our translation) But, Camille and Tony later thought, approaching all this in terms of "dysfunctions where the departments interact" was dangerous because it referred too visibly to "frictions" between particular individuals. They finally had to come up with another strategy. This is where the particular slideshow we analyze enters the scene. How did this new framing come about? Did it "work" well on the audience? How consultants concretely put together a representation of the hospital's dysfunctions that would entail a positive change? In what follows we attempt at answering these questions by following the consultants in the drafting of the diagram that encapsulated the new strategy.

Following a diagram's life

A systemic approach to dysfunctions

Camille gave instructions to Tony so that he could start drafting the slideshow. She suggested him to "start with the merger, insisting on the fact that the merger is not over yet, no one will complain or deny that, and the result is that perimeters are fuzzy inside each department, and the organization suffers from a lack of direction" (Field notes, January 2010, our translation). On this ground, she asked Tony to make "formal proposals", i.e. to figure out a proper layout that would somehow put the merger forward in the representation but also take into account the conclusions of the audit. He made a first draft on PowerPoint which eventually served as the basis for a brainstorming meeting between the two consultants, which we describe in what follows. Several comments were handwritten during the encounter, as can be seen on Figure 1.

- ---------------------- ----------------------- At first sight, Camille found the idea of a synthetic and graphical representation interesting, with different thematic "boxes" that could be developed further in the report: "[Camille to Tony:] I like this approach because we need to show that problems are systemic. It is a good way not to be trapped in a silo-type of modeling, without a view on overall issues of governance. But we also need to show that the organization did not capitalize on good practices throughout the merger; what was right in each structure was not re-used." (Field notes, January 2010, our translation) On this first draft of the diagram, the "uncompleted merger" is put forward (circle in the center) to comply with Camille's instructions. The other elements of the analysis are then dispatched on the page. The top management (represented by the red ["Management/project"] box) is also endowed with a central position. According to Tony, it is a way to manifest that the members of the board can be held responsible for major dysfunctions in the hospital and notably the failure of the merger in terms of systems integration and corporate culture.

Camille reacts to this representation by expressing concerns about the very content of the analysis. She asks Tony to provide concrete examples for each box, which he handwrites on the right of the page. He mentions "frictions at interaction points", gives examples of dysfunctions such as "adm patient mgt and store", quotes several information system tools used in the hospital. Camille herself pushes the analysis (handwritten remarks on the left) using the document as a "thinking aid" which fades behind actual considerations on the hospital's dysfunctions. Among other things, she gives details on what the consultants' have come to consider as a lack of top management: "The size of the hospital calls for urgently implementing a formalized steering framework: strategic plan, management by objectives, reporting, etc." (ibid).

Camille and Tony also question the causal relations between the elements displayed in the boxes, as is shown by the multiple arrows handwritten on the page. They try to discern "real causes" from "symptoms" and Camille repeatedly asserts that "everything is in everything" and that "there is always something artificial in this kind of structuration" (ibid).

However, the consultants spend considerable time discussing the relevance of the boxes' repartition, the appropriate titles for them, and the actual interactions between the elements of the system. As an outcome of this discussion, Camille suggests the inclusion of a new box, "structure", in which issues of managerial decentralization ought to be addressed. And because she is getting "fully convinced by this systemic approach", she warns Tony that the titles yet don't meet her requirements and they'll have to be better defined. The meeting reaches an end, and Tony is asked to keep on working on the diagram in that direction. But before he leaves the room, Camille adds this last remark: "I know it is important to you but it would be counterproductive to point out the top management in a straightforward manner. So I'd rather prefer you get this red box ["Management/project"] back in the rank, at the same level with the others" (ibid).

"Entering through the merger": a diagram of attribution

After that brainstorming meeting, Tony drafted a new version of the diagram taking into account Camille's comments (Figure 2).

- ---------------------- The diagram has the function of attributing responsibility to selected targets, the function of assigning agency. In a sense, it organizes a program of action in the semiotic sense studied by, for example, [START_REF] Bencherki | Having to be: the possessive constitution of organization[END_REF]. Camille mentions a necessity to "enter through the merger" as a way to step in the argumentation, to step in a world performed by a representation that contributes to distributing accountabilities for the hospital's dysfunctions.

That's where the difficulty lies: attributing responsibility without really doing so, displaying problems without overburdening anyone, so as not to turn the targeted people against the analysis. The fact that the consultants chose a "non-human", the merger, a sort of process without subject, as the first cause for dysfunctions, is considered a way to "gently get the message across" (ibid).

At that point Camille suggested to Tony an exercise that consisted in a sort of a simulation of the rhetoric capacity to describe the diagram, much like a rehearsal. Camille asked Tony to explain the boxes, to make explicit the content, the message, the intention as if he was talking to the client. Tony, who was not used to this type of method, felt slightly embarrassed, almost as if he was participating in some sort of breaching experiment. Again, the aim was to provide examples for each box and discuss the relations between them. On several occasions during the exercise, Camille repeated the same sentence, as a leitmotiv of their consulting work: "what do we want to say, what do we want to show, what is the effect we want to have on the client" (Field notes, January 2010). In the end, mostly out of exasperation, Tony responded straightforwardly: "The answer is simple: we want to say that everything is wrong in this organization and that everything is linked. We do not want to stigmatize the top managers, in particular the head of human resources who is already in a bad position, and the top management. But, frankly, their responsibility is total. We have decided to use the merger as an entry point. And then we have a pile of very clear things to say, but we need to dose them: outdated processes, lack of motivation, absence of field management, wrong deployment of information systems, flaws in the store logistics, administrative management of patients, well, I don't need to tell you all." (Field notes, ibid, our translation) This kind of questioning was a way for Camille to make sure that the representation as it appeared in its material form corresponded to the message the consultants wanted to display. Because once created, the artifact travels, takes a life of its own and can be misinterpreted (or interpreted without the control of the consultants). It also met one of Camille's expectations about the conception work of a narrative artifact. In her view and as she often said (quoting the French poet Boileau-Despreaux) "what is conceived well is expressed clearly": the enunciation style was then treated as a mark out for the redaction work.

A complex network of publics

As we mentioned earlier, Effictio Consulting's assignment had to align with the work of another consultant, Mister K, a longtime collaborator of Aeger Hospital. At this time, Camille and the Partner at Effictio who headed the mission had an important meeting with Mister K to discuss the reorganization in regard with the strategic planning he was carrying out. Camille reported to Tony on the outcomes of the meeting: "[Camille]: 'the meeting with Mister K is going to have an impact on the structure of the report and the diagram, an important impact. We need to organize things so as to make sure that Mister K's input is taken into account. Otherwise he is going to tackle us down'. She said she felt judged, though the objective of the meeting was rather to discuss the information system master plan and to position Effictio Consulting with respect to Mister K's strategic planning. According to her, Mister K asked the Partner:

'Tell me what you are going to present to the CEO and to the other members of the Board'. Camille did so. Mister K reacted: 'You have to go beyond symptoms and start addressing human resources, processes, organization and tools'. […] Camille found Mister K's analyses rather hard, even peremptory. […] [Camille said:] 'I have the impression that Mister K and the CEO are fond of each other and that he is there in order to challenge us. I have discussed with the Partner at Effictio whether or not we should be aggressive in front of the CEO, saying that Mister K's proposal is rubbish.

We don't know yet. I am going to talk to the CEO to gather some impressions on the topic'." (Field notes, January 2010, our translation) At that stage in the drafting process, the diagram was embedded into a slightly novel context. It had to cope (critically or not) with the criteria and vocabularies put forward by a competing consultant. Camille indicated to Tony that Mister K's "little boxes" (i.e. the titles used in the boxed texts inside the diagram) needed to be used: "Human Resources" (skills, capabilities, size), "processes" (issues of fluidity and clarity), "organization" (that is, who is responsible for what) and "tools" (information systems and work methods). We see here that the diagrammatic representation works as a collaboration device "that allows for the achievement of agreement around information being communicated" (Kaplan 2011, p. 331).

The document is the result of an iterative process between competitors; it becomes a means through which "distributed knowledge got negotiated and embodied" (ibid, p. 332).

Representational sources of inspiration

With these elements in mind, Camille asked Tony for new improvements in the diagram:

"[Camille to Tony:] I really think that the idea of the diagram is good. We will work further on the boxes to be sure they are right and that they fit Mister's K analysis.

But the diagram is not nice. It's actually quite dumpy. We know that everyone in the hospital is going to read this particular slide: it's a global diagram on Aeger's dysfunctions… so it really needs to be a killer." (Field notes, January 2010, our translation)

As we can observe, the next remarks of the senior consultant thus turn slightly aesthetic and communicational. We are now moving from the ground of precautious attribution and interested collaboration to the ground of efficacious communication. The amusing thing to notice is that, in Camille's view, "not to stigmatize" is about not having an effect, but then what about "being a killer"? At this stage, Tony is looking for sources of inspiration to make the presentation more aesthetically fit, that is, for what he calls "diagrammatic templates" that can be used as examples. He searches Effictio Consulting databases, but also examines examples from a competitor he obtained a few months before from a colleague and discretely reuses sometimes. Figure 3 illustrates an example that came out of this diagrammatic modeling process based on formal exercises:

------------------------Figure 3 about here ------------------------ Camille reacted to this layout proposal with mixed feelings. It was considered as nice, as "being a killer", but it looked "too consultant" in her view, i.e. difficult to "swallow" by the Board of a hospital, too distant from the culture of the CEO. She forwarded to Tony another model "much simpler in terms of form […] basically it is a circle in the middle with several boxes around "(Field notes, January 2010, our translation). It also had hardly anything to do with the assignment terms of content as it was entitled: "the advantage of training mapping for training managers" and discussed issues of organizational learning. A widespread criticism of management consulting focuses on the fact that consultants use the same models over and over, irrespective of the context of the consultancy mission and the specify of the situation. In the case analyzed here, this mimetic fashion appeared as appropriate, but as an aesthetic of structuration, not as an analytical device. Camille considered the slideshow as "a source of inspiration" for organizing thoughts regardless of its meaning.

Tinkering with boxes and arrows

On the basis of this model, Tony drafted a new version of the diagram (Figure 5).

------------------------Figure 4 about here ----------------------- This new version of the diagram displays a yet higher level of sophistication. The "uncompleted merger" is put forward (in bold at the center of the page), Mister K's analytical categories are mentioned in the boxes which are further explained with details of the analysis.

The use of bullet points to align the examples is also considered a way to reinforce and better target them.

The problem of managerial stigma and the attribution of sharp responsibilities surfaced again at this point in discussions between Camille and Tony. The color code (red) for the upper "management" box was too garish and therefore "still stigmatizing" for top management. It was decided that all boxes should use the same color code. The light arrows had to be revised too. According to Camille, the arrow between "organization" and "process" introduced an annoying asymmetry in the diagram and was to be removed. She then came to the conclusion that the extensive use of other arrows was also confusing and asked for them to be entirely removed. [START_REF] Pinto | Graphique et science d'entreprise[END_REF] argues that using arrows in a graphic representation is equivocal, because the nature of the relation between the terms "is tacitly conceded to the act of reading. So far as possible, what is suggested is […] a causal relation: in this case the global configuration may seem to work as a sort of explanatory model of reality. But if the reader does not accommodate with a strong (causal) interpretation of the arrow, he can still put up with a weak interpretation, that consists in taking the sign for a formal and empty indication (X "has to do with" Y) impossible to reject, for the very reason of its indetermination" (p. 97). In our case, one can see indeed that the figuration of causal relations is abandoned by the consultants in favor of a circular and all-comprehensive structuration (see Figure 6), that ought to speak for itself, prevent the audience from confusion and foster personal interpretation.

Moreover, Camille considered that there was too much text on the page and that it would be sound to simplify the examples, or even to erase the upper texts that actually "did not bring about much added value". Figure 5 is the next version of the diagram, which includes the last comments.

- -----------------------Figure 5 about here -----------------------

A matter of wording

Camille scheduled a meeting with the Partner to run the latest draft of the diagram past him. He found the idea of the diagram interesting and its formalization efficient. However, he made several comments regarding the choice of words, the "wording" as even French consultants usually say using the English language. First, he insisted on the fact that the diagram had to be "freestanding", i.e. capable to speak for itself and to be understood by a neophyte without a simultaneous oral explanation by the consultants. As a result, any jargon or non-explicit terms had to be expunged, such as "orphan tasks" for example. Second, he argued that there were too many negative words in the slideshow and summoned the consultants to avoid putting forward a negative vision of the organization: "[Partner]: I find the report way too violent. You see, there are two ways to get the message across. Either we say 'this is lame, you're all good-for-nothings', either we use the managerial approach, that means we say 'you are good but you still have areas of improvement to consider' […] you don't need much to tone down the topic […]; I am convinced that the client is smart enough to understand the message without us saying it.

[Camille]: I agree with you but I was trying to meet the client's requirements, he asked for the report to hurt, for us not to be easy with them… it is an explicit request from the client.

[Partner]: beware what the client asks you Camille, he comes from the public sector. He fosters a culture of confrontation. We must be better than that. We must challenge him and not take a share in spreading his mistakes." (Field notes, May 2010, our translation)

To challenge the client by bringing him softly toward positive change is one of the effects the Partner expects from the diagram. But as he further explains, this implies drifting away from the client's requirements, which also has to do with the consultants' logic of selfpreservation. Indeed, they will be directly associated with the artifact they produce, and will have to cope directly, as service providers, with the effects it might produce: "[Partner:] We have to know to which extent we are ready to put up with the after-effects of violent words, especially during a meeting. The executive manager is smart enough to have his own weapons against us, after 8 month of assignment, this makes no doubt." (Field notes, May 2010, our translation)

Reaching a "rock solid" diagram

The next version of the diagram was then amended accordingly. The details for each box were, for example, slightly modified. In the case of the "human resources" box: "few specialized profiles" is replaced by "insufficient number of specialized profiles"; "employee discouragement" by "strong risk of employee discouragement"; "no shared culture in the new organization" by "no shared culture in the new organization yet". This type of softening of the wording can also be observed in the other boxes such as "governance" (where the proposition "flaws in the steering of support functions" is simply removed) and "tools". In the same vein, the Partner insisted on the fact that the term "uncompleted merger", at the center of the page, was "too strong and too connoted" and needed to be replaced. All the more, for him, the crux of the problem was not the fact that the merger was ill-completed, but the fact that the organization had increased in size, which were two very different things, which he discussed extensively with Camille (see Figure 6).

- ---------------------- ---------------------- Both Tony and Camille were satisfied with that final version. While considering the job done so far before going to a meeting with the clients, Camille remarked: "our diagram really shines… even though we can say it is a two man-day diagram, at least now it is 'rock solid' ["béton" in French]". Perceiving the diagram as "rock solid" was for the consultant the result of a series of iterations and compromises: promote a systemic approach to dysfunctions, enter through the merger not to stigmatize anyone, display an aesthetic layout with coherent causal relations, remain thorough in the analysis, provide in-depth and well-structured examples, enhance a positive discourse and challenge the client, secure the consultants' mission, and so on. All these elements, incorporated in the representation, were part of the recipe to compose a visual rhetoric that could perform a new state of the world. Now, the diagram had the strength to resist further iterations and circulate in wider circles of public in felicitous conditions. Now, it may generate a suitable reality for the client.

Presenting the diagram

It would be quite perilous to evaluate the concrete effects of such slideshow beyond its observable reception by clients. Connecting the process of diagrammatic composition to the transformations that occurred afterward in the hospital, on a relatively long timescale, would be highly contestable, unless an ethnographic work similar to the one conducted on the slideshow's production could reveal the phenomenon that allow the connection to be asserted.

A few clues regarding its reception by clients may, however, hint to some effects and contribute, in a sense, to the closure of our work on the slideshow's production.

Camille recalled the way she handled the presentation (Tony was not present), "entering through the merger" as decided:

"[Camille to Tony:] I first said positive things, and I explained: 'You were two small-scale organizations, you managed to function with a particular way of doing things, and while today you are a single organization, you still inherit from these two cultures, process, resources, and that is not adapted anymore'. I then showed the diagram, and everyone was very impressed, and I zoomed in for each box. According to the Partner and Camille, who were in charge of the presentation, the diagram caused a "strong impression". Two types of remarks were put forward. First, a notion of clarity and order attributed to the format of the slide itself was valued by clients. A member of the Board would say for example that the diagram "gives a good picture of the situation of the hospital, now at least all is clear". Another said that the consultants "put a name on every problems and some sort of clear relation between all of them". This naming and ordering quality is common in such types of representation which create a common ground for people to discuss and build upon [START_REF] Quattrone | Books to be practiced: memory, the power of the visual, and the success of accounting[END_REF][START_REF] Kaplan | Strategy and PowerPoint: an inquiry into the epistemic culture and machinery of strategy making[END_REF]. Other would directly point out the material aspects of the representation as one of its major effects. For example, in discussions with Camille and Tony, the Head of Information Systems would add: "There is nothing new, but now it is written in stone and nobody will be able to say that we didn't know" (Field notes, May 2010, our translation).

Other reactions referred to the hospital's situation as such, as if representation (the diagram) had gradually substituted itself to the world, in a chain of reference: "These are management methods of another age, how come we don't use management by objectives".

One Board member also indicated: "I refuse that this translates into a witch hunt," for it seemed, despite the consultants' efforts, that the diagram was still attributing responsibilities for the dysfunctions in the hospital.

Discussion

Three constraints for pragmatic efficacy

As we have seen in this empirical account, the diagram is not a blank representation: it says things about the world, about the way consultants interprets problems and clients' expectations, even their own condition. What it says, and how, has to be understood in relation to particular constraints, which govern its evolution to a great extent. We identify three main constraints that affected the work of Camille and Tony for the drafting of the diagram: (1) to create an appropriate effect on the target, (2) to be faithful to the "reality" of the situation and (3) to maintain an internal coherence of the representation. Of course, these three constraints were intertwined in practice. For example and as we have seen, if the consultant removes an arrow from the diagram for the sake of graphic symmetry, it is also an explanatory link that goes off the analytical edifice, and a managerial responsibility that is not spotted anymore. When the consultant wonders if he can use such word as "uncompleted merger" to describe the situation, he bears its relevance as a signifier for a dysfunction in the hospital, and also its potential appreciation by the clients. But these three constraints are analytically distinct and allow for an understanding of the empirical issues raised by the problems of the felicitous consultancy presentation.

First constraint: considering effects

The first constraint is to produce expected effects on the target. At any given moment in the process of writing the report, we observe, the consultants were acutely aware that they were in a "communication situation", and that their recommendation would have a strong impact on the organization. The impact was mostly seen in terms of "political consequences", especially because the message displayed attributed responsibility for the lack of efficiency of processes. As a result, the different arguments carried by the diagram have been worked on and hierarchically ordered by the consultants. Two messages are put forward: first, the merger is responsible for dysfunctions in the organization; second, dysfunctions are systemic. In both cases, the idea is to avoid pointing directly at someone's particular responsibility, especially that of top management. Furthermore, the expected "political effect" not only involves the client organization, but also the consultants, as part of an interacting system. Consultant bears the possible counter-productive effects of their message in terms of image and commercial matters. And yet there is a third target: Mister K, the other consultant, who was in charge of strategy for Aeger Hospital, and whom Camille and Tony had to deal with. The titles of the boxes displayed in the slideshow were borrowed from his analysis, in order to seek adhesion.

The diagram then works, partially, as a coordination device between consultancy service providers, and the sought effect is approval from a potential competitor. This, of course, points to a performative understanding of managerial devices, or of economic instruments in general. For example, the consultancy slideshow plays here a role comparable to that of the business models analyzed by [START_REF] Doganova | What do business models do? Innovation devices in technology entrepreneurship[END_REF]. These are considered not as simplified descriptions (accurate or not) of a company, but as demonstrations, as performances which seek at provoking situations and initiating courses of action. The felicitous consultancy slideshow (that is, a solid one, one that works) is characterized thus in part by attention to the effects it may have inside a strategic, often delicate configuration. These effects have not only to be understood in the sense of making the organization change in a direction closer to the one depicted by the consultants, a sense often associated to a narrow understand of performativity in the construction of markets (MacKenzie, Muniesa and Siu 2007). What the authors of the diagram want to create, above all, is a situation in which their position inside a network of strategic actors (managers inside the client organization, competitors in consulting, and partners within the consultancy firm) is kept relevant.

Second constraint: considering accuracy

The second constraint consists in providing a representation that is faithful to reality.

We observe that the construction of the diagram results from constant transfer and exchange between what is referred to and what refers to it, that is, between the consultants' conclusions on the functioning of the hospital (their vision of its problems) and the diagram that shall represent them. In our case, the reference process, considered both as account-taking and molding of the world, is perhaps most visible, for example, in a will to be "exhaustive", i.e. to encompass every aspect of a rather finite reality, to produce detailed examples behind any assertion or at least be "ready to illustrate" orally what has been stated, or use appropriate qualification for the titles of each part of the diagram. Consultants here seek to be accurate, to be faithful to their analysis of the reality of the client organization. It is intriguing to observe how consultants, when they are in the heat of the action, do share and put to work a tacit agreement on the reality of their claims. At no point was the veracity of the diagram put into question by Camille or Tony. Rather, the status of the diagram as an intermediation towards reality fades away in favor of a sense of transparency with which the consultants talk about reality through the diagram.

This echoes a discussion initiated by Latour in his works on scientific reference [START_REF] Latour | Pandora's Hope: Essays on the Reality of Science Studies[END_REF]. According to Latour, the sciences do not have a mirroring relation to world, but produce representations which contribute to building it objectively. Reference is not what can be pointed out from outside, a mere reflection of a world per se; it is "rather what remains constant through a series of transformation" (Latour 1993: p. 205 our translation). Unfolding these transformations sheds light on intermediaries that carry the work of translation and contribute to stabilize a suitable version of the reality. Reference is not a closed circuit where anybody can make up any fantasy and expect it comes true. It is an engagement with the world "out there", where one can identify at every stage, "a common operator, which belongs to matter at the one end, to form at the other, and which is separated from the stage that follows it by a gap that no resemblance could fill" (Latour 1999: 69). In our case, we see, the pragmatic efficacy of the slideshow relies on the tensions of proof: how to achieve the felicitous transportation of elements that back its claims?

Third constraint: considering layout

The third constraint is to put forward a fine internal, formal coherence. This refers in part to the coherence between the diagrammatic presentation and the accompanying documentation in terms of content, wording and analysis. But it also refers, perhaps more interestingly, to the visual coherence of the diagram proper. Here, coherence needs to be interpreted in terms of neatness and proportion. It is, for instance, about caring for symmetry in the layout of the representation and about favoring the harmonious arrangement of boxes, titles, arrows, words and sentences. This constraint is not considered by the consultants in the terms of the purely sophistic craft of the smack of seriousness, but rather as a rule that governs the rigor of analysis-qua-communication and the consultancy forma mentis.

Along with [START_REF] Quattrone | Books to be practiced: memory, the power of the visual, and the success of accounting[END_REF] we identify a form of aesthetic of the methodology displayed in the diagram. Despite the content, the form itself plays a strong role of simplification, clarification, and ordering that finally make the diagram appropriable by the client. The representation becomes an object that can be used as soon as it is grasped by the audience as easily usable [START_REF] Quattrone | Books to be practiced: memory, the power of the visual, and the success of accounting[END_REF]; in our case, simple, schematic, clear. Other observers criticize this aspect of business schematic representation by considering it as a form of oversimplification that "maintains confusion between the register of science and the register of the aide-mémoire" (Pinto 1987, p. 93). Instead, [START_REF] Quattrone | Books to be practiced: memory, the power of the visual, and the success of accounting[END_REF] argues that "because it leaves the user free to enact that space" (p. 112) which is offered in the blank of the representation, it becomes performable. Using arrows or replacing them by a simple circle in order not to favor a too straightforward interpretation: this would be a particularly appropriate illustration of such concerns in the analyzed case.

Pragmatic efficacy

What is the kind of reality that is carried by the diagram? What kind of reality does it refer to? To interrogate the faithfulness of the representation of the real is a difficult business.

The referential object is an explicit concern for the consultants. But concern for the real is not only concern for the accuracy of the referential object. The consultants do also care, in this direction, for the legitimacy of their analyses and proposals, for the (structuring or destructuring) effects that the diagram can have for the organization, for the pedagogical capacities of the diagrammatic device and for its inner harmony. Pragmatic efficacy, considered as a positive, productive way of representation, is best encapsulated in the idea of solidity and resistance ("béton") that the diagram reaches at the end of the drafting process.

We have observed the draft of the diagram evolve through a series of constraints. Coherence was sought. But coherence was a matter of tinkering and iteration, a matter of incorporation of aspects, a matter of trials of resistance. Coherence was, in our view, about producing a coherent match between layout, accuracy and effect.

Our analysis of the ethnographic material combines a grounded, inductive approach to a commitment to a pragmatist viewpoint on the problem of symbolic efficacy. The analytical outcome consists chiefly in the identification of the three constraints that we just isolated in this section and which correspond to occurrences in the empirical description. These three constraints connect to the pragmatist angle in a variety of manners. But the most salient connection is perhaps with the theory of signification defended by Charles S. Peirce. We conjecture that the three constraints communicate with three aspects of signification that Peirce emphasizes in his analytical distinction of the symbol, the index and the icon (Hooper 1991, Kockleman 2005; see also [START_REF] Muniesa | Market technologies and the pragmatics of prices[END_REF]. Layout has to do with the iconic capacity of the diagram, that is with the ability to delineate a graphic rendering of the consultancy analysis. Accuracy relates to the indexical capacity of the diagram, to the possibility of tracing diagrammatic items back to the consultancy inquiry and its object. Effect connects to the symbolic capacity of the diagram, to its facility to enter and accompany a collective assemblage, a system of conduct, a socially organized space. If we consider, thus, the diagram in the slideshow as a sign in a pragmatist, Peircean way and we ask what this sign requires in order to signify felicitously, we can conjecture that it needs to act effectively as an icon but also, to a certain extent, as an index and as a symbol. The consultants, we can say, need to achieve this complicated taskcomplicated and at times contradictory, and definitely fragile.

What consultants do when they address the "organs" of the client organization definitely falls into the scope of the "manipulation of symbols" that Claude Lévi-Strauss alludes to in his essay on "symbolic efficacy" in remedial rituals [START_REF] Lévi-Strauss | L'efficacité symbolique[END_REF]. Our of management consulting. Consultants combine multiple constraints. They do not seem to rely on a univocal idea of how managerial reality should be signified, but are instead able to navigate within a plurality of signification modes that waver between layout, accuracy and effect. Our ethnographic analysis is of course contingent and limited, but we estimate that this insight can be of use for the interpretation of the pragmatic efficacy of management consulting in other situations.

-Figure 1

 1 Figure 1 about here

Figure 1 :

 1 Figure 1: A rough first draft of the diagram, amended

-Figure 2

 2 Figure 2 about here

Figure 2 :

 2 Figure 2: Second draft of the diagram

Figure 3 :

 3 Figure 3: Draft for diagrammatic improvement

-Figure 5 :

 5 Figure 5: Fourth draft of the diagram

-Figure 5 :

 5 Figure 5: Seventh draft of the diagram

  Figure 6 about here

-Figure 6 :

 6 Figure 6: One of the final versions of the diagram

  […] And I ended up with what hurt the most: the bosses, the governance." (Interview with Camille, October 2010, our translation)

Figure 2 :Figure 3 :

 23 Figure 2: Second draft of the diagram

Figure 4 :Figure 5 :Figure 6 :

 456 Figure 4: Fourth draft of the diagram

The reason for using the grammatical third person and a pseudonym for the first junior consultant (who is of us) is purely stylistic. We do not tackle here, for lack of space and of specific purpose, the reflexive aspects of participatory ethnography.

Acknowledgements

We thank Nicolas Bencherki, Paolo Quattrone, François-Régis Puyou, Christine McLean, Juliette Ricou and Antoine Hennion, for comments and remarks on this work. A previous version of this paper was presented at the 2nd Workshop on Imagining Business (EIASM, IE Business School, Segovia, 19-20 May 2011). The research on which this paper is based has benefited from funding from the Association Nationale de la Recherche Technologique (Convention Cifre No. 516/2009) and from the European Research Council (ERC Starting Grant No. 263529).