• Rôles des organisati ons professionnelles dans le développement de l'élevage laiti er au Maroc

N. Belkadi -Fédérati on Nati onale des Éleveurs PROducteurs de Lait -FENEPROL

• État actuel du marché du lait et des produits laiti ers au Maroc

  A. Benkirane -Fédérati on Nati onale de l'Industrie Laiti ère -FNIL• La consommati on de produits laiti ers au Maroc : quelles tendances ? N. Bour -Professeur à la Faculté des Sciences -Kénitra Contraintes hydriques et production laitière : concepts et défis futurs • Ressources en eau et développement laiti er : quelles conséquences pour les politi ques publiques dans les pays à stress hydrique ? M.T. Sraïri, IAV Hassan II, Rabat, Maroc • Ressources en eau et élevage laiti er en Inde : les révoluti ons verte et blanche inti mement liées ? C. Aubron, B. Dorin, M. Vigne et O. Philippon, Sup Agro, Montpellier, France • Le lait de chamelle : nouvelle fronti ère du développement laiti er dans les pays du Sud ? B. Faye, CIRAD, France CONTACT : lait2017@inra.fr SITE WEB : http://colloque.inra.fr/lait2017 vecteur de développement lait le Rencontres organisées par l'IAV Hassan II, l'INRA et le CIRAD en partenariat avec IAVFF-Agreenium


Christophe Chassard

Teagasc, IE Paul Cotter

Valérie Gagnaire

Gilles Garric

Teagasc, IE Kieran Jordan

UCC, IE Alan Kelly

Teagasc, IE Kieran Kilcawley

Sylvie Lortal

Teagasc, IE Olivia Mcauliffe

UCC, IE Paul Mc Sweeney

Marie-Christine Montel

Romain Richoux

Diarmuid Sheehan

Anne Thierry

CNIEL, FR Véronique Pilet

John Hannon

DK Chr Hansen

Michel Britten

Paul Cotter Teagasc

Pdo Cheeses
email: cheese2018@inra.fr

Luca Settani

Drivers of technological changes in cheese manufacture

Keywords:

This 10 th Cheese Symposium continues a tradition to showcase recent developments in both fundamental and applied research. It is organized by INRA in collaboration with Teagasc and University College Cork. It aims to cover a broad range of themes associated with ongoing cheese research and current market trends.

The conference will provide a unique forum for academia and industry to share experiences on the latest developments and applications of cheese research. The program will appeal to all involved in cheese research or production.


domain: sdv shs

text:
Julia Grimault

Valentin Bellassen

Igor Shishlov

challenges in monitoring, certifying and financing forestry carbon projects

A reliable monitoring, reporting and verification (MRV) of carbon removals or emissions reductions is necessary to access most carbon payments. After an overview of forest carbon finance, this Climate Brief presents the different options and challenges associated with forest carbon MRV.

Projects developers face three key choices: the project scope (carbon pools to be considered, geographical perimeter and the related leakages or indirect emissions reductions), the different techniques and tools for forest carbon monitoring (field measurements, modeling or) remote sensing) and the baseline definition and additionality demonstration.

Despite the different tools and guidelines available to help projects developers trigger impactful mitigation action, six main technical and political challenges are identified:

• The non-permanence risk and carbon debt: while standards provide tools (e.g. buffer account, ex-ante credits) to deal with this challenge, finding the right balance between environmental integrity and project profitability remains delicate.

• Monitoring uncertainty is often put forward as a barrier to the implementation of carbon pricing in the forestry sector. Reduce uncertainty is costly and the interest of doing so depends on whether carbon pricing is voluntary, on the importance of information asymmetry and on projects profitability.

• The risk of windfall effects: additionnality can never 100% guaranteed. There again, striking the right balance between avoiding both the "false positives" (non-additional projects getting registered) and the "false negatives" (additional projects that are shut out by the cost and risk of the additionnality demonstration) is delicate.

• Verification costs: verification can weight up to half the MRV costs and cannot usually be internalized.

• Low carbon prices: typical MRV costs for forestry projects are around € 0.15-1.4 per tCO 2 eq which is substantial when carbon prices average around € 3 per tCO 2 eq on voluntary markets. How to combine a robust certification with the financial viability of carbon projects in this context is challenging.

• The double-claiming of climate action issue: the Kyoto Protocol safeguards against double-counting between countries have been adapted by some voluntary carbon standards to prevent that a private entity and a country claim the same emission reduction. This has slowed down projects implementation in Annex I countries, but several standards, including the Gold Standard, are moving towards a new paradigm for voluntary carbon markets.

Introduction: No finance without monitoring

The concept of payments for environmental services (PES) -such as reducing greenhouse gas (GHG) emission or enhancing their sinks through forestry projects -has been very popular since the mid-2000s. Although the development of actual PES schemes has not kept pace with the popularity of the concept, the amount of finance for forest carbon projects has never been as high as in 2015 when it reached USD 888 million (Goldstein & Ruef, 2016). It also stayed important in 2016 with USD 662 million (Hamrick & Gallant, 2017). In most cases, these payments -be they part of mandatory or voluntary programs -are contingent on successful certification of the program. Indeed, the 19 th COP 1 of the UNFCCC in 2013 has enshrined the result-based payment principle.

Certification is necessary in order to guarantee the quality of a project and to assure that it yields tangible environmental benefits, such as reduced GHG emissions. Economic benefits for forestry carbon projects can come in various forms including payments based on the amount of CO 2 emissions reduced/sequestered, payments based on implementing sustainable practices or indirectly through certification of wood products. The most widespread type of forest carbon finance is carbon crediting. It consists of issuing carbon credits for certified GHG emission reductions, which can in turn be sold on compliance or voluntary carbon markets. In any case, monitoring and certification practices are similar across carbon pricing and management mechanisms, no matter whether they entail the issuance of carbon credits.

This Climate Brief begins with an overview of forest carbon finance. The main options in forest carbon MRV are then presented along three categories: the definition of project scope, the different techniques available for forest carbon monitoring, and the accounting choices pertaining to baseline definition and additionality demonstration. Finally, a list of six challenges is discussed: non-permanence, uncertainty, windfall effects, comparability of reported figures, low carbon costs and double-claiming of climate action.

1 Conference of Parties Two major international standards certify the sustainability of forest management: Forest Stewardship Council (FSC) and Program for the Endorsement of Forest Certification schemes (PEFC). They ensure both forest management sustainability and wood traceability all along the production chain, up to the customer. Among other criteria, the controlled wood should not come from illegally deforested areas (FSC).

Zero-deforestation supply chain

Civil society and companies launched initiatives, such as Forest 500, Supply Change or Global Forest Watch Commodities, to promote and assess 0% deforestation commitments. These pledges are mostly related to raw materials that are the main causes of deforestation: palm oil, wood products, soybeans and livestock.

However, they do not constitute a proper standard certifying that a specific product is deforestation-free. So far, work has been initiated to assess the traceability of products, to select relevant indicators and to harmonize sustainability procedures between companies.

Nevertheless, for some raw materials such as palm oil, the elaboration of global schemes evaluating the impact of the production on deforestation is more advanced:

• In 2008, the Roundtable on Sustainable Palm Oil (RSPO) developed a so-called CSPO certification, based on the analysis of socio-environmental criteria. This scheme ensures that the commodity has been cultivated on nondeforested lands.

• Since November 2016, the High Carbon Stock Convergence (HSC) Agreement works on the harmonization of two existing approaches aiming at fighting deforestation induced by palm oil plantations.

Technical and accounting options for forest carbon certification

Result-based payments rely on monitoring, reporting and verifying (MRV) the amount of emissions avoided or of carbon sequestered by a given program. Monitoring stands for the collection of the data, e.g. through direct measurements or the use of proxies, necessary for calculating the amount of emissions within a given scope and timeframe. Reporting includes the aggregation, recording and communication of this data to the relevant authorities. Finally, verification aims at detecting errors and/or fraudulent reporting and is usually conducted by an independent accredited third party. The object of MRV is either GHG emissions or -in the case of carbon projects -GHG emissions reductions, i.e. the difference between actual and counter-factual -or baseline -emissions.

Define the scope of the project

Monitoring reforestation or improved forest management projects amounts to counting carbon sequestration -or emissions -in the newly planted forest or improved forest and the emissions related to forestry operations (transportation, plowing, seeding, thinning, …). Carbon sequestration/emissions can occur in six compartments or carbon pools (IPCC 2006), although, depending on the methodology, not all six necessarily need to be monitored:

• Above-ground biomass: including stems, branches and the foliage of trees as well as non-woody vegetation and shrubs. • Below-ground biomass: including living roots.

• Dead wood: including non-living biomass such as standing or lying on the ground stumps or buried dead roots. • Litter: non-living biomass with a diameter less than a certain threshold defined in the methodologies. It also includes decomposing lying deadwood. • Soil organic carbon: including all soil components derived from plants and animals. • Harvested wood products.

In most cases, the project developer has to prove that all six pools do not decrease and then choose to account specifically for some of the categories. Thus, most generic methodologies only require accounting for above-ground and below-ground biomass. IFM methodologies usually include the harvested wood products pool, which may decrease in reduced logging methodologies for example (Deheza, 2014). Non-biomass related emissions sources such as field operations or input transportation are often considered de minimis and are therefore not monitored (Deheza, 2014).

Along with carbon sequestration and emissions directly linked to the project activity, standards usually require calculation of emissions indirectly affected by a project, most commonly referred to as "leakage". For example, leakage can result in emissions from the displacement of pre-project agricultural activities, or from increased harvest indirectly driven by an IFM project that decreases harvest locally.

A forestry project can also allow for emissions reduction in other sectors through substitution effects: wood can be a substitute for fossil fuels or energy-intensive construction materials and allow emissions reduction in energy or building sectors. However, those indirect effects are not taken into account in current project-based mechanisms on voluntary or compliance markets.

Monitor carbon stocks

Three main types of methods can be used to measure forest carbon stocks and their evolutions: field measurements, modeling and remote sensing. 4 Each of these approaches have different levels of precision and therefore, evaluating carbon sequestration sometimes requires a combination of Field measurements -generally restricted to the diameter and height of trees from a representative number of sample plots -have historically been the only type of monitoring allowed in forestry projects. It was indeed feasible to use this technique for reforestation projects covering limited areas. However, as the share of IFM and REDD+ programs covering large and diverse forested areas rose, the use of modeling and remote sensing became unavoidable. The second way to assess carbon stock and flows in forests is based on empirical and process models that, according to a given initial stock, estimate the evolution of that stock over time. The most simple and commonly used type of model is the so-called "look-up tables", which predict the evolution of a series of forest stand variables with age for a given species and fertility index in a given region. More generic and complex models exist which require data such as project boundaries, temperatures, precipitations, soil type, slope, species, etc. Several studies (Vashum et al. 2012 5 & Kuyah et al. 2015 6 ) stressed that the use of such models could be less expensive than on-site measurements. Finally, remote sensing methods also allow monitoring of land area changes (and notably leakages that the project could potentially create), stratification of the project area, and analysis of vegetation types. 7

Current methodologies for forest carbon projects often mix these three approaches to evaluate carbon sequestration. For example, the methodology for Improved Forest Management Through Extension of Rotation Age (IFM ERA) of the VCS will monitor project area through remote sensing, require data from the most relevant literature to run models estimating carbon sequestration and on-site measurements to make sure the allometric equations used in the model fit well with reality.

Determine baseline and demonstrate additionality

The carbon impact of a project is assessed against a reference, or baseline scenario. The carbon benefits of a forestry project do not equal its total sequestration, but rather the difference in sequestration between the project and reference scenarios over time. The construction of this reference scenario is therefore an essential step of carbon project monitoring.

The accumulation of fifteen years of experience in the CDM resulted in a tool dedicated to baseline construction and additionality demonstration. The general idea is to start from all alternative land use scenarios considered realistic and credible with regards to relevant national and/or sectoral policies, and narrow them down to the most profitable and/ or most common practice. Some methodologies also have specific requirements on the type of reference eligible. For instance, methodology VM0005 from VCS requires the baseline to be a logged-over natural Evergreen Tropical Rainforest with no or insignificant regrowth and this needs to be proven in order to apply this methodology for the accounting of GHG emissions and absorptions.

In all existing standards, the baseline is set at a small scale -the project scale -and is not standardized: it is up to the project proponent to propose "realistic and credible" alternatives to the project. In the literature however, the pros and cons of this choice are discussed. A regional or national average has been considered a pertinent baseline in some cases. Van Benthem and Kerr (2013) show that whenever large scales can be chosen for both project and baseline, the efficiency of the PES is improved. Similarly, Bento et al. (2015) show that a stringent standardized baseline may be a good option to limit windfall effects.

In order to be certified and generate offsets, carbon projects have to be additional: carbon finance is key to the project implementation. In close relation to baseline determination, two main options are used by certification standards to demonstrate additionality:

• A standardized method ("positive lists"), which sets the objective criteria that the project has to meet. The methodology can propose for example a list of underimplemented technologies, so a project using one of these technologies would automatically be considered additional.

• An individualized method, which consists in submitting the project to a set of «tests» and requires alternative scenario(s). The common tests are the legal test (the project activity is not a legal obligation), the financial test (the project activity is not the most profitable scenario), the barriers test (technical or cultural barriers prevent the implementation of the project activity), etc.

In 2016, over half of forest carbon projects reporting to Ecosystem MarketPlace on their funding sources declared receiving their entire revenue from the sale of forest carbon offsets (Hamrick & Galant, 2017).

Key challenges linked to forest carbon certification

Bellassen and Stephan (2015) provide a detailed description of challenges related to the MRV of GHG emissions and emissions reductions, based on the actual decisions made by the regulators of the fifteen most important carbon pricing and management mechanisms. Two of these mechanisms are specific to forestry programs. The following section is largely inspired from this book.

Forestry specificities: non-permanence risk and carbon debt

The main specificity of forestry carbon projects is that the permanence of the climate mitigation benefit they provide cannot be fully guaranteed: the storage of carbon in forest biomass and soil is reversible. Different methods are used to assess and deal with this non-permanence risk, which comes with afforestation and improved forest management projects. Certification standards provide tools relying on the analysis of relevant criteria describing the occurrence of natural disasters, the political context of the project implementation's region, or the financial capacity of the project proponent. Most standards set aside a part of the project's total credits into a 'buffer account', which is debited to replace offsets that have been issued from projects where the carbon initially sequestered has been re-emitted. Those credits are not delivered to the project proponent and therefore lower the total carbon revenue.

Other solutions have been implemented -such a temporary credits -or proposed -such as ton-year accounting -to transform non-permanent sequestration into carbon credits.

Many potential IFM projects face another challenge, namely a kick-off period during which carbon benefits are small, if not inexistent. Indeed, improving management practices often implies cutting trees to replace them or allow their neighbours to grow faster in the long run. This may entail an initial "carbon debt" which can take decades to be offset by enhanced tree growth and fossil fuel substitution (Agostini, Giuntoli, and Boulamanti 2013). This differs from other types of projects (agriculture, energy), which may deliver credits within a year after the beginning of the project. The "carbon debt" adds to the economic challenges for forestry projects, especially when the project implies high costs at the beginning (plantation, thinning…). Some carbon finance channels thus include ex-ante payments or ex-ante carbon offsets to address this challenge and provide an incentive for the project to be launched.

Monitoring uncertainty and costs

Monitored values come with an uncertainty, i.e. may differ from the real values. This uncertainty stems from systematic errors (bias) and/or random errors. Uncertainty of carbon stocks is often put forward as a barrier the implementation of carbon pricing mechanisms in the forestry sector (European Commission 2012). In order to limit uncertainty, the regulator may prescribe the uncertainty level by mandating the use of default values, set a minimum certainty threshold, or discount the benefits of emissions reductions proportionally to uncertainty. Among these three options, the most efficient choice is sometimes not to care about uncertainty and in any case depends on the nature of the certification framework -mandatory or voluntary, on the importance of information asymmetry and how profitable mitigation projects are (Bellassen and Shishlov 2016). Most existing carbon pricing mechanisms provide only limited (if any) incentives to reduce monitoring uncertainty (Bellassen et al. 2015).

For CDM reforestation methodologies, sampling error is the only source of error considered in the computation of uncertainty. The other possible sources of error, such as the carbon density of wood, measurement errors or allometric factors8 , are neglected.

More precise monitoring may be costly, which in some cases constitutes a major barrier to the implementation of projects. For example, Pearson et al. (2013) quantified monitoring costs in carbon sequestration projects to be in the range of 3% to 42% of total project costs. Monitoring costs in forestry projects are subject to both fixed and variable costs as generalized by Cacho et al. (2004Cacho et al. ( )O. et al., 2004. Fixed costs include for example the costs of transporting monitoring teams into project areas, while variable costs depend on the size of the project and the number of plots (salaries, transportation costs between the plots, data entry and analysis costs). The presence of important fixed costs explain why monitoring costs are proportionally higher for small projects than for bigger ones. The project developer has to make trade-offs between costs and monitoring precision. A higher precision is sometimes rewarded with more offsets but is always more costly.

Most forest methodologies require stratification of the project area into relatively homogeneous units. The different strata can be defined according to vegetation types, planting date and management plans, soil types, natural impacts altering the pattern of biomass distribution, etc. Stratification is useful as it can either increase the measuring precision without unduly increasing the cost, or reduce the cost without reducing measuring precision because of the lower variance within each homogeneous unit. When performing stratification, the differences among various strata should be easily identifiable. A faulty stratification increases the uncertainty estimate, which encourages the project proponent to come up with a robust stratification. The more effort is put on stratification and sample size, the lower the uncertainty, and if lower uncertainty is rewarded, hence the more credits are received.

Additionality demonstration: the risk of windfall effect

Additionality demonstration also represents an important part of certification costs. Half of the costs of drafting the project document is spent on additionality and reference scenarios in the case of «individualized» demonstrations (Guigon, Bellassen, Ambrosi, 2009). A «standardized» additionality demonstration can contribute to the reduction of certification costs: it is objective and simple and makes the project validation easier as it avoids individual demonstrations. Indeed, 65% of failures for CDM certification are due to an «individualized» demonstration deemed unconvincing by the standard (Castro and Michaelowa, 2008). Of course, it also comes with the pitfall of a possibly high "windfall effect" due to projects which fulfill the standardized demonstration without the need of any additional action or incentive.

More generally, the problem of the additionality evaluation is that it requires the assessment of alternative hypothetical scenarios, which will never materialize if the project is implemented. This means that additionality can never be established with a 100% certainty. In this light, the additionality issue becomes a question of finding the right balance between the amount of non-additional projects that manage to get registered -so-called "false positives"-and the amount of additional projects that do not manage to pass the additionality test or that are frightened away by the cost and risk of the demonstration -"false negatives"that represent lost opportunities (Trexler, Broekhoff, and Kosloff 2006).

The French Energy Saving Certificates scheme, for example, opted for standardized methods. These have been praised for their ease of use and the low costs entailed, but the resulting additionality is between 0% and 50%

Reporting and verification: relevance vs comparability

The challenges and opportunities related to reporting are quite simple and mostly revolve around the trade-off identified by Cochran et al. (2015) between information relevance and comparability. Reporting frequency, reporting language, the level of aggregation of emissions sources and the level of standardization of the reporting format are the four most important considerations in this regard (Bellassen and Stephan 2015).

In practice, verification rules are relatively similar across carbon pricing and management mechanisms (Bellassen et al. 2015). In particular, most of them do require the verification of the reported information by independent and accredited third parties. Variations are found on verification frequency, the nature of the third party (individual vs firm), the materiality provisions9 , the control modalities of this third party and the support provided to them.

The auditor, which is often a firm, shall confirm that that the requirements of the standard and the method have been followed. This entail checking the accuracy of the estimates and the consistency between the monitoring report and field evidence (supporting accountancy documents, stakeholder feedbacks, etc.). In most cases, verification includes a site visit. Classical auditing principles such as risk-based assessment and materiality are applied: the auditor spends more time on the most important or uncertain sources of emissions reductions, and often cannot mandate a revision of the monitoring report when the errors found are below a materiality threshold (often set to 5% of the amount of emissions reductions at stake).

Most of the time, the balance between auditing costs and revenues from carbon credits drives verification frequency, estimated between 5 to 10 years for forestry projects (Deheza, 2014). In terms of verification costs, Chenost and Gardette (2010) estimate a cost range between 20-50k€ per verification incurred by project developers. Third-party verification represented between 25% and 50% of forest projects revenues in 2016 (Hamrick & Gallant, 2017).

Combining robust and comprehensive MRV with low carbon prices

On the demand side, robust MRV and certification is of paramount importance for buyers. On voluntary carbon markets, nearly all offsets transacted in 2015 (98%) were developed under a third-party standard (Hamrick & Goldstein, 2016). In France, robustness of certification is a key parameter for organizations to get involved in carbon offsetting. Certification of multiple social and environmental co-benefits is also a key driver of demand (I4CE, 2017). Those high certification requirements often imply high MRV costs -typically € 0.15-1.4 per tCO 2 eq for forestry projects (Bellassen and Stephan 2015), which contrast with the relatively low prices companies are willing to pay for carbon credits (I4CE, 2017).

The importance of MRV costs for the financial viability of carbon projects naturally depends on the carbon price.

In the "golden age" of the CDM -before carbon prices collapsed in 2012 -MRV costs did not seriously impact the financial attractiveness of projects in most sectors. However, as the cumulative supply of CERs hit the upper limit for their use in the EU ETS -the main source of demand for carbon credits -market prices collapsed below USD 1/ tCO 2 eq (Stephan, Bellassen, and Alberola 2014). Carbon prices on the voluntary market seem to be more resilient in the time of crisis than JI/CDM credit prices as they remained above USD 3/tCO 2 eq, but are still relatively low. The price for voluntary forest carbon offsets is slightly higher: $ 5,2 for all project types, and it rises up to USD 9.5/tCO 2 eq for IFM projects and USD 7.5/tCO 2 eq for A/R projects (Figure 3). In theory, voluntary credit buyers are usually ready to pay a small premium for carbon credits with multiple social and environmental benefits, which is often the case for forestry projects. In practice, this premium is not visible in actual carbon prices (Ecosystem MarketPlace, 2016).

That is why, in the current market circumstances, transaction costs play a significant role for the financial viability of carbon projects, especially for small-scale projects implying high investment costs, as it is the case for most European forestry projects.

Conclusion

Solid MRV is a necessary condition to forest carbon finance. However, forestry projects face technical, accounting and economic challenges that the current carbon prices do not always allow to overcome easily.

Many tools have already been implemented in the past decade by the different carbon standards to deal with forest projects specificities and simplify the certification processes (buffer account, standardized additionnality demonstration…). However, several avenues can still be explored to reduce certification costs while insuring environmental integrity: methodology requirements, additionality demonstration, verification processes… These options must be weighed against potential losses in economic efficiency and environmental integrity on a caseby-case basis.

In France, stakeholders have been addressing these challenges related to MRV and project certification with the development of the Label Bas-Carbone 11 . It is a national carbon certification framework designed to support various policies and needs, such as carbon offsetting, environmental subsidies, public sector procurement, etc. Inspired from the literature and experience summarized in this document, its guidelines offer different options -revolving around the discount principle -to strike the best trade-off between cost and precision of MRV on a project per project basis.

However, reducing transaction costs is not the only option to promote the development of mitigation projects in the forest sector. The current carbon price on voluntary markets ($ 3/tCO 2 eq for all project activities) is considered low to allow for a strong development of mitigation projects, especially when compared for example to carbon taxes levels in developed countries -where lies most of the demand for offset s : $ 139/tCO 2 eq in Sweden, $ 76/tCO 2 eq in Finland, $ 55/tCO 2 eq in France , $ 25/tCO 2 eq in the UK, $ 27/tCO 2 eq in British Columbia, $ 23/tCO 2 eq in Alberta for example 12 . Better communication to all stakeholders about MRV and carbon finance is also therefore needed, in order to solve the paradox between buyers' high expectations on environmental integrity and low willingness to pay for certification standards which support it. Finally, one must keep in mind that the guaranties offered by MRV can be a basis for several types of carbon related finance for forestry, far beyond carbon offsetting. Those applications of MRV legacy to different types of finance for forestry needs to be assessed and further developed.

FIGURE

  FIGURE 2. ILLUSTRATION OF A CARBON PROJECT

  FIGURE 1. REPARTITION OF RESULT-BASED FINANCE TO FOREST PROJECTS IN 2015 (TOTAL: $ 888 M)

	0%	20%	40%	60%	80%	100%
	Voluntary Carbon Market
	Compliance Market (e.g. New Zealand, California, etc.)
	Australia's Emissions Reduction Fund
	Non-Market Agreement (e.g. REDD+ Programs in Brazil)
	Source: Ecosystem Market Place, 2016 *
	* The 2017 update of this study signals difficulties in retrieving figures from
	California.

For more information, see Brûlez et al. (2018) : Building synergies between sustainable forest management certification and carbon certification: what bases are there and for what impact?

R. Birdsey et al. 2013, Approaches to monitoring changes in carbon stocks for REDD+, Carbon Managementrke tools in order to improve the accuracy while reducing the costs of monitoring.

https://www.omicsonline.org/methods-to-estimate-above-ground-biomass-and-carbon-stock-in-natural-forests-a-review-2157-7625.1000116. pdf

6 http://samples.ccafs.cgiar.org/measurement-methods/6-quantifying-treebiomass-carbon-stocks-and-fluxes-in-agricultural-landscapes/

Allometric factors are commonly used to estimate whole tree biomass, including branches and roots, by extrapolating easily measurable parts such as the trunk.

Materiality implies that an auditor should focus on the riskiest parts of what is being audited, and pay more attention to larger numbers than to smaller ones (Bellassen and Stephan, 2015).

http://www.goldstandard.org/sites/default/files/documents/a_new_ paradigm_for_voluntary_climate_action.pdf

Création-réalisation : SophieBerlioz.fr

Acknowledgements

This work has been finance by the European Commission's Climate-KIC.

Climate-KIC is supported by the EIT, a body of the European Union

Bibliography

• Agostini, A., J. Giuntoli, and A. Boulamanti. 2013


Luisa Fernanda Orozco
email: luisa.orozco@umontpellier.fr

Duc-Hanh Nguyen

Jean-Yves Delenne

Philippe Sornay

Farhang Radjai

DISCRETE-ELEMENT SIMULATION OF PARTICLE BREAKAGE INSIDE BALL MILLS: A 2D MODEL

Keywords: Granular material, grinding, ball mills, DEM, Bonded Cell Method, Contact Dynamics Method

In this paper, the grinding of powder inside a ball mill is studied using the Bonded Cell Method (BCM) implemented in the framework of Contact Dynamics. In BCM the parent particles are divided into cells that are glued to one another until, under the action of external loading, both a cohesion threshold and a certain distance threshold are reached. Numerical simulations of a rotating hollow cylinder filled with a mixture of heavy balls and powder crushable particles were carried out. Systems with balls of different sizes and/or numbers are compared in terms of the evolution of the powder particle size and specific surface. We find that, in general, the milling process is increasingly faster as the ball size increases. But energy dissipation due to increased collisions between balls slows down the grinding process and makes it energetically less efficient. On the other hand, when the total volume of balls is kept constant, the ball size is not relevant for the evolution of particle breakage except in the limit cases of very small and very large ball sizes.

INTRODUCTION

Ball mills are widely used in multiple different industries such as agronomy, mining, pharmaceutical. In these applications, ball mills are mainly used for grinding, breakage and mixing. It has been estimated that in Australia, just in the mining sector, the grinding process consumes 36% of the total energy, which corresponds to 1.3% of Australia's energy consumption [START_REF] Ballantyne | Proportion of energy attributable to comminution[END_REF]. For these reasons, understanding the behaviour of granular materials in ball mills is crucial for the improvement of the operational conditions and consequently a reduction on energy consumption. Some studies have been performed in order to evaluate the performance of ball mills regarding the choice of operational parameters, material properties and milling conditions. Commonly, properties such as the particle size distribution, powder specific surface, powder density, breakage rate, collision energy and collision frequency are compared among different systems in order to evaluate the grinding energy efficiency and the effectivity of particle size reduction [START_REF] Francioli | Effect of operational variables on ball milling[END_REF][START_REF] Erdem | The effect of ball size on breakage rate parameter in a pilot scale ball mill[END_REF][START_REF] Gupta | Effect of size distribution of the particulate material on the specific breakage rate of particles in dry ball milling[END_REF]. In many experimental studies of ball milling, the amount/range of the parameters tested is limited, and therefore inconclusive results are found. This gap may be filled by numerical simulation, which currently has its own challenge of reconciling numerical performance with the realism of the underlying physical model.

A few DEM models have been developed in order to simulate particle breakage inside drum mills. Some use the bonded particle method (BPM) in which the parent particle is composed of smaller spheres agglomerated [START_REF] Metzger | Simulation of the breakage of bonded agglomerates in a ball mill[END_REF]. Inside the drum, the agglomerates are ground due to the interactions with bigger unbreakable balls, walls and other agglomerates. However, in this method, the particle volume is not conserved. In another approach sometimes used, a particle is replaced by a collection of smaller spheres once a breakage criterion is achieved [START_REF] Cleary | Charge behaviour and power consumption in ball mills: Sensitivity to mill operating conditions, liner geometry and charge composition[END_REF][START_REF] Wang | DEM investigation of energy distribution and particle breakage in tumbling ball mills[END_REF]. Since the particle replacement is done using a population balance model, the volume is conserved but, all the particles and their fragments keep their spherical shape, and therefore the milling process cannot be modelled in full by this methodology.

In this paper, we consider the Bonded Cell Method (BCM) in 2D, which has the advantage of keeping the volume of particles and allowing for arbitrary irregular polygonal shapes of the particles and their fragments during the milling process. We briefly introduce the BCM in the framework of the Contact Dynamics (CD) method. Then, we present the results of two groups of numerical simulations of grinding inside a ball mill, which we analyze to investigate the effect of operational parameters on the evolution of particle size and specific surface as a function of the number of revolutions. As the numerical efficiency of DEM simulations strongly declines with the number of particles, one crucial aspect of this work is to show that realistic simulations can be performed using our approach with a good representation of the ball-particle mixture.

NUMERICAL METHOD

Bonded Cell Method (BCM)

In the BCM, each particle is modelled as an assembly of fundamental elements to which we will refer below as 'cells'. Thus, when a particle breaks, the fragments generated are smaller particles each composed of cells, the smallest fragment being a single cell (representing the lower bound on particle size). In order to define the cells configuration, a Voronoï tessellation is performed on each particle. The mean cell size (d cell ) is fixed so that a parent particle of surface s consists of approximately s/d cell 2 cells. A parameter α accounts for the cell shape heterogeneity, taking the value of 1 for very similar cell shapes, and 0 for very dissimilar cells. In previous work applying BCM it was found that setting α close to 1 leads to nearly crystalized cell configurations with higher mechanical strength [START_REF] Cantor | Three-dimensional bonded-cell model for grain fragmentation[END_REF]. To avoid such effects, in this work α is set to 0.5. The generated cells are convex polygons that are in perfect contact with their neighbours. In this way, each parent particle is perfectly tessellated without defects nor voids. Figure 1(a) displays an example of a collection of pentagonal particles partitioned into irregular cells. Since the cells have a polygonal shape, various contact types can be expected, i.e. side-side, vertexside, vertex-vertex. Initially, cohesive bonds are assigned to all side-side interfaces. The side-side contacts are represented by two points belonging to their common contact line (see Fig. 1(b)). Initially, the contact lines coincide with the common sides between cells. Mechanically, a contact can lose its cohesive status only if some strength and distance criteria are fulfilled. In our model, these criteria are defined as a function of the distance between the points of contact.

We introduce three parameters for the cohesive behaviour among cells: a normal stress threshold (C n ), a friction coefficient (𝜇), and a distance threshold (𝜀). The first criterion must be fulfilled in order to allow the relative movement between the two cells to occur. In the normal direction, the stress threshold is C n and in the tangential direction is C t = 𝛽 C n . The parameter β is not a friction coefficient but simply a scalar relating normal and tangential stresses. Once two contact points reach a separation distance equal to 𝜀, the cohesive status is lost irreversibly and a purely frictional behaviour will govern future interactions between the two cells with a friction coefficient 𝜇. Since the cohesion is applied at the side-side interfaces, the threshold forces are calculated as the product of the stress threshold and the interface length ℓ. A graphical representation of this cohesive-frictional model is shown in Figure 2. All the other contact types between cells and with the drum walls present a purely frictional behaviour (see Fig. 3). The above model represents a rigid-plastic behaviour. No elastic strain is present because of the rigid nature of the elements. At a cohesive interface, reaching the stress threshold will trigger the plastic deformation (irreversible), that resembles a crack growth.

Contact Dynamics

The numerical simulations are carried out in the framework of a DEM method known as Contact Dynamics (CD) [START_REF] Moreau | Some numerical methods in multibody dynamics: application to granular materials[END_REF][START_REF] Radjai | Contact dynamics as a nonsmooth discrete element method[END_REF]. As in Molecular Dynamics (MD), in CD the equations of motion for all rigid bodies are integrated in time, taking into account the momentum conservation in the presence of the forces and moments due to contact between particles and, bulk forces such as gravity. In contrast to MD, an implicit scheme based on an iterative Gauss-Seidel algorithm is used in CD. This leads to unconditional stability of the time-stepping scheme that permits choosing larger time steps. The CD starts with a geometrical research of potential contacts in two steps. First, a rough selection of the neighbours with a search distance, followed by a narrower detection in which the positions of the geometrical features of the two particles potentially in contact are compared. Then, through an iterative algorithm, the forces and velocities are solved for all the potential contacts at the end of each time step. Finally, the particle velocities and rotations are calculated and the positions are updated. There is not a unique solution for perfectly rigid particles in CD but, the initialization of the contact forces at the beginning of the time step with the values found in the previous step reduces the set of solutions, such that the variation between solutions is below the numerical solution fluctuations [START_REF] Moreau | Some numerical methods in multibody dynamics: application to granular materials[END_REF]. Another parameter that must be set in CD is the restitution coefficient. Usually, it is defined from the relative velocities after and before a collision between two particles, such that it is zero for a completely inelastic shock and 1 for perfectly elastic collisions. The notion of restitution coefficient is included in CD by replacing the contact velocities (u n and u t ), defined in the Signorini and Coulomb relations at the end of each time step, by weighted means as follows:

𝑢 ( =
where 𝑢 ( < and 𝑢 ) < are the relative velocities at the beginning of the time step in the normal and tangential directions, respectively, 𝑢 ( 1 and 𝑢 ) 1 are the velocities at the end of the time step, and e n and e t are the restitution coefficients in the normal and tangential directions. The Signorini relation (see Fig. 3) determines that a contact takes place when u n = 0 implying that 𝑢 ( 1 = -𝑒 ( 𝑢 ( < , which is the classical definition of restitution coefficient.

Sample setup and tests

In order to simulate grinding inside a ball mill, a hollow cylinder of an internal diameter of 15 cm is filled with powder and balls. The powder volume is fixed as well as its material properties and those of the grinding bodies for all the studied cases (see Table 1). An important characteristic of our model is that all the elements have polygonal shapes, the powder particles are pentagons while the balls are hexadecagons. The use of polydisperse pentagons prevents from the creation of local crystallized structures often found in mono-disperse packings of hexagons and squares [START_REF] Nguyen | Effect of size polydispersity versus particle shape in dense granular media[END_REF][START_REF] Wu | Dynamic modelling on the confined crystallization of mono-sized cubic particles under mechanical vibration[END_REF]. The powder particle sizes are defined using a uniform particle volume fraction from d min = 0.002 m to d max = 0.003 m. In general, the size of a polygonal particle is defined by the diameter of its circumscribed circle. Finally, the sample is tested by applying a constant speed of 50 rpm to the cylinder for a duration of 60 seconds. Snapshots at different times of a test show the evolution of the grinding process inside the drum (see Fig. 4). The flow regime inside rotating drums is generally described by the Froude number 𝐹𝑟 = 𝜔 * 𝑅/𝑔 [START_REF] Mellmann | The transverse motion of solids in rotating cylinders-forms of motion and transition behavior[END_REF]. In our simulations, Fr is 0.21 and the tested systems exhibit a cascading-cataracting regime. Two cases are considered in this study. In the first case, the effect of the ball size D b is studied, whereas in the second case the number of balls (N b ) is varied. In the first case, five samples were built with filling degree of 0.6 and a ratio between the balls and powder volumes (V b /V p ) equal to 3.3. The filling degree is defined as the ratio of the apparent volume of the mixture powder-balls and the drum total volume. Since a constant amount of powder is used in all simulations and the ball size is variable, it is expected that the number of damaged powder particles will change from one sample to another.

The size D b is the same for all the balls in a given sample and takes values of 5, 10, 15, 20, 25 mm. Three samples of this case are displayed in Figure 5(a). For the second case, the size D b is constant and equal to 15 mm for the five sets of simulations. As in the first case, the powder volume is kept constant and thus the drums filled with different numbers N b of balls present different filling degrees different values of the ratio V b /V p (see Table 2). In Figure 5(b) images of three samples of the second case are shown. In Table 2, some geometrical relations of the two studied cases are presented. Table 2. Geometrical characteristics of the systems studied.

First case

Second case

D b (mm) D drum /D b (-) D b / 𝑑 K (-) U (-) N b (-) Filling degree (-) V b /V p (-) U (-) 5

RESULTS

Effect of ball size (D b )

Figure 6(a) shows the mean powder particle size 𝑑 normalized by the initial mean size 𝑑 K as a function of the number of revolutions for different values of ball size D b . The filling degree, total ball volume V b , and total powder volume V p have the same value in all cases. This means that D b N b , where N b is the total number of balls is constant, and thus when we increase D b , the number of balls declines. We observe slow size diminution at the beginning. Then, the size diminution is accelerated almost exponentially for the next 10 revolutions before slowing down again exponentially with powder particle size reaching a value close to the cell size. The transient occurs more or less early depending on the ball size, but we do not observe a monotonic dependence. Figure 6(b) displays the evolution of the total specific surface S normalized by the initial specific surface S 0 with the number of revolutions. The specific surface increases nonlinearly with the number of revolutions. Interestingly, besides D b =5 and D b =25, the evolution curves coincide for all other values of ball diameter. This is consistent with the data points of Figure 6 In the case of the smallest value of D b , where D b /D p =2, the milling is very similar to the case of powder ground without balls. Since the breakage events are concentrated on at the downstream of the free surface, as observed in Figure 7, the dominant breakage mechanism is the impact of particles, including both powder particles and balls, with the powder particles downstream of the free surface. Late grinding occurs in this case due to the balls low inertia: smaller amounts of kinetic energy are carried by small balls in comparison to big ones, and therefore the impact energy is transmitted to the powder in small amounts. As noted by Erdem and Ergün [START_REF] Erdem | The effect of ball size on breakage rate parameter in a pilot scale ball mill[END_REF], the small balls are suitable for reducing the small powder particles rather than the big ones which are mainly broken by impacts of high collisional forces.

In the case of large values of D b with D b /D p =10, fewer impacts but of higher magnitude are expected [START_REF] De Carvalho | Predicting the effect of operating and design variables on breakage rates using the mechanistic ball mill model[END_REF]. In Figure 7 the multiple breakage events that are located at the downstream boundary with the drum wall can be linked to cases in which one or multiple grains are crushed between the wall and a ball that approaches with a large amount of kinetic energy. Also, this map shows that multiple breakage events occur in the space between balls (with its signature as dense rings), which is a feature not observed for D b =5 mm. However, in this case, the grinding process is slower than for other diameters because the powder particles are trapped in the pores between the balls, becoming inaccessible and therefore protected. This result was also found in [START_REF] Erdem | The effect of ball size on breakage rate parameter in a pilot scale ball mill[END_REF].

Between the two extreme cases discussed above, the intermediate cases show a gradual grinding transition that does not seem to depend on the ball size. This must be understood as the result of the fact the total volume of balls is kept constant. As the kinetic energy is proportional to the volume, the observed behaviour suggests that the surface created by milling is proportional to the kinetic energy and hence should be independent of ball size. We see that the transition in terms of the specific surface and average powder particle size is increasingly faster as the number of balls increases except for N b =50. As the total volume of the balls increases, the collisions between balls becomes increasingly dominant and more energy is dissipated as a result of ball collisions. In the limit N b =50, this dissipation is excessively high. Indeed, as observed in a snapshot of the ball mill in Figure 9 in the case N b =50 the balls often form long impulsive force chains. In the other extreme case of N b =10, the filling degree is low, implying that the flow regime of this system is slumping-rolling, in which some of the particles can remain intact at the core, rather than the cascading-cataracting regime, characterized by the impact between powder and balls particles. For this reason, the transition curve in Figure 8 for N b =10 is slightly different and the specific surface tends to a lower asymptotic value than for other values of N b . Figure 10 shows maps of breakage events for the different number of balls tested. We observe that breakage occurs in all cases almost everywhere inside the flow with more events downstream of the flow.

CONCLUSIONS

In this paper, we presented the bonded-cell method (BCM) developed on a Contact Dynamics platform and applied to the grinding of brittle materials inside ball mills. We performed simulations of a rotating cylinder containing a powder (breakable pentagonal particles) and balls (unbreakable disks). The effect on the reduction of particle size and changes of the specific surface were investigated for two groups of parameters. In the first group, the ball size was varied with a constant total volume of balls. In the second group, the number of balls was varied. In both cases the total number of powder particles was kept constant. We showed that the grinding behaviour (transient from the initial breakage to the ultimate state of nearly no breakage event) is mainly influenced by the number of balls. The grinding is faster as the number of balls and hence the total kinetic energy increases. However, for a large number of balls, this trend is counterbalanced by enhanced energy dissipation due to increased collisions between balls. In the case where the total volume of balls is kept constant, changing the ball size does not affect the evolution of grinding as the total kinetic energy is nearly the same. Here too, the extreme values of ball size correspond to special flow configurations that govern the grinding behaviour. Our simulations show that the BCM approach can be used efficiently for realistic simulations of ball mills with a large number of revolutions.

Figure 1 .

 1 (a) Voronoï tessellation applied to polygonal particles. Each cell is presented in a different colour; (b) The geometry of a side-side contact between two cells.

Figure 2 .

 2 Behaviour of a cohesive interface a) Signorini relation in the normal direction; b) Coulomb friction law. ∆ n and ∆ t are the displacements between the two cells in the normal and tangential direction, respectively. 𝜀 ( and 𝜀 ) are related through 𝜀 ( * + 𝜀 ) * = 𝜀 * where 𝜀 is the distance threshold.

Figure 3 .

 3 Behaviour of a purely frictional contact a) Signorini relation in the normal direction, b) Coulomb friction law in the tangential direction. u n and u t denote the particles relative velocities in the normal and tangential directions, respectively.

Figure 4 .

 4 Figure 4. Snapshots of a ball mill at numbers of revolutions. The powder particle colours go from bright green (intact) to black (highly damaged).

Figure 5 .

 5 Snapshots of some of the samples tested. a) Samples with balls size D b of 5 mm, 15 mm and 25 mm from left to right; b) Samples with balls numbers N b of 10, 25 and 50. The thickness of the red lines is proportional to the magnitude of the normal force.

  Figure6(a) shows the mean powder particle size 𝑑 normalized by the initial mean size 𝑑 K as a function of the number of revolutions for different values of ball size D b . The filling degree, total ball volume V b , and total powder volume V p have the same value in all cases. This means that D b N b , where N b is the total number of balls is constant, and thus when we increase D b , the number of balls declines. We observe slow size diminution at the beginning. Then, the size diminution is accelerated almost exponentially for the next 10 revolutions before slowing down again exponentially with powder particle size reaching a value close to the cell size. The transient occurs more or less early depending on the ball size, but we do not observe a monotonic dependence. Figure6(b) displays the evolution of the total specific surface S normalized by the initial specific surface S 0 with the number of revolutions. The specific surface increases nonlinearly with the number of revolutions. Interestingly, besides D b =5 and D b =25, the evolution curves coincide for all other values of ball diameter. This is consistent with the data points of Figure6(b) in which the evolution of the mean powder particle diameter for D b =5 and D b =25 is slower than for other diameters.

Figure 6 .

 6 Evolution with the number of revolutions of a) normalised mean particle size, b) normalised specific surface, for different value of ball size. The filling degree, total balls volume V b , and powder volume V p are constant. Each curve consists of 1000 data points.

Figure 7 .

 7 Figure 7. Spatial localization of breakage events in drums filled with balls of variable size: from left to right 5, 10, 15, 20, 25 mm, respectively.

Figure 8 .

 8 Evolution with the number of revolutions of a) normalized mean particle size and b) normalised specific surface, for different numbers of balls (N b ). The ball size D b and the powder volume V p are constant. Each curve consists of 1000 data points.

Figure 9 .

 9 Figure 9. Force chains in a simulation with N b = 50, the thickness of the red lines is proportional to the magnitude of the normal force.

Figure 10 .

 10 Figure 10. Spatial localization of breakage events in drums filled with balls of size 15 mm. From left to right the number of balls (N b ) is 10, 20, 25, 30, 50, respectively.

Table 1 .

 1 Material properties of the powder and balls used in all simulations.

	C n (MPa)	1
	𝜇 (-)			0.4
	𝜀 (m)			1.00E-06
	𝑑 F2GG (m)	5.00E-04
	𝜌 I (kg/m	3 )	2030
	𝜌 J (kg/m	3 )	11000

ACKNOWLEDGMENTS

The authors would like to acknowledge the funding and expertise from the CEA.


Oats is only sixth in world cereal production (after wheat, maize, rice, barley, and sorghum) Brazilian oat production (tons)

Oat grain among cereals

What is holism?

Holism (from Greek holos "all, whole, entire") is the idea that natural systems and their properties should be viewed as wholes, not as collections of parts. This often includes the view that systems function as wholes and that their functioning cannot be fully understood solely in terms of their component parts

Non linear multicausal relationship 2 > 1+1

Parable of the blind men and elephant

Holism vs Reductionism

Holism vs Reductionism in the cereal sector A holistic view of cereal grain

Mechanisms involved according to reductionism

The concept of grain package and multi-functionality: a multicausal non linear relationalship

Cereals as a source of lipotropes

Compounds that act on lipid metabolism by preventing fat accumulation within the liver through:

hastening fat removal (e.g. via increased phospholipid synthesis for lipoproteins → VLDL secretion, a TG-rich lipoprotein) -preventing excessive fat deposits/decreasing rate of deposition:

• Increased lipid b-oxidation • Decreased triglyceride synthesis
The term "lipotropic" was first used in 1935 by Best et al. who showed that choline is able to prevent and cure fatty livers in rats and that increased liver fat infiltration and accumulation was primarily due to deficiency in some essentials factors whose the principal role is to assure lipid transport and turnover •

Fiber compounds:

-Phytic acid -Soluble and insoluble fiber oligofructose

• Polyphenolic compounds:

- Phenolic acids - Flavonoids - Lignans - Stilbenes - Saponins - g-oryzanol - Curcumin - Phytosterols? - Alkylresorcinols?
• Others:

- Organosulfur compounds - MUFA/PUFA - SCFA - Mélatonine - Policosanol? - 1-Deoxynojirimycin - …unknown?
• Those only found in animal products: • Different nutritional effects?

• Germination :

• Germination is the resumption of development and metabolism -water absorption (wicking), respiration, enzyme activity, etc.of a spermatophyte embryo until it becomes a mature plant; this germination is naturally inhibited as the seed is in the fruit, and often for some time

• Pre-fermentation : -interferes with the peristaltic mixing process in the small intestine to impede digestion and absorption of nutrients -precipitates satiety signals through increased interaction with the cells that release satiety hormones stimulating the release of peptides involved in appetite regulation.

• However: inconsistent results of the effects of oats on satiety.

• Whether delivered in a whole food or an extract from the food, oat βglucan appears to have a positive effect on perceptions of satiety.

Oat products & health: A literature review Weight regulation & Satiety

Poutanen, K., M. Lyly, et al. (2010). "Rye, Oats, and Weight Management." Cereal Foods World 55( 2): 66-69.

"Thus, it seems that adding oat βglucan to beverages could boost their satiating capacity compared to beverages without fiber."

"In addition, the lowering of a beverage's viscosity, containing 10 g of β-glucan, by enzymatic treatment reduced the satiating effect, which stayed higher than that of a beverage without β-glucan."

"ß-glucan increased plasma cholecystokinin (CCK) levels in a dose-responsive manner, indicating beneficial effects of ßglucan on postprandial appetite control and GI peptide release."

The inconsistent results of the short-and long-term studies do, however, suggest that in the longer term, some other factors, such as environmental, social, and psychological factors, are still more powerful determinants of food intake and body weight.

Oat products & health: A literature review Gut microbiota

Rose DJ. Impact of whole grains on the gut microbiota: the next frontier for oats? Br J Nutr. 2014;112:S44-S9.

• Oats are a unique whole grain that may contribute distinctive effects on the gut microbiota.

• These effects could be due to:

-the high b-glucan content: -the high lipid content -the unique antioxidant profile.

• Oat lipids and antioxidants (fibre co-passengers?) have not been studied in relation to gut health, but research in other whole grains suggests that they influence the types of bacteria that make up the microbiota and impact on host health.

1. "Regular consumption of oats and oats products can lower plasma levels of total cholesterol and LDL.

2. A dose-dependent response is evident with oat bran having the strongest effect.

3. An approved UK cholesterol reduction claim requires at least 0.75 g oat bglucan to be delivered per portion.

4. This can be achieved by consuming oat products such as porridge, ready-toeat breakfast cereals, bread, cereal bars and pasta. Myriam Grundy; Anthony Fardet; S. Tosh; Peter Wilde. Processing of oat: impact on its health benefits. To be submitted.

It is difficult to draw firm conclusions, notably related to the potential matrix effect.

Increasing the degree of matrix complexity led to conflicting results concerning its impact on lipemia.

However, study design, status of subject, food matrices, molecular weight of β-glucans appear to greatly differ from study to study making comparison hazardous.

Three hypotheses may be advanced but that request further confirmation: • N = 34 studies.

• Meals (0.3-12.1 g oat b-glucan) reduced glycaemic response by an average of 48 mmol.min/l compared to a suitable control.

• Change in glycaemic response was greater for intact grains than for processed foods.

• For processed foods, glycaemic response was more strongly related to the bglucan dose alone than to the ratio of b-glucan to the available carbohydrate.

• For processed foods containing 4 g of b-glucan, the linear model predicted a decrease in glycaemic response of 27 mmol.min/l, and 76% of treatments significantly reduced glycaemic response.

• Intact grains as well as a variety of processed oat foods containing at least 4 g of b-glucan and 30-80 g available carbohydrate can significantly reduce postprandial blood glucose Seven studies were identified of cancer risk (two each on prostate and colorectal cancer, and one each on pancreatic, breast and endometrial cancer), and one study on overall mortality With the exception of a case-control study of pancreatic cancer, all studies were of cohort design

The results of most cohort studies suggest a weak protective effect of a high intake of oats on cancer risk (RR  0.9)

("

  MUFA/PUFA ratio = 20/37/42% Wheat SFA/MUFA/PUFA ratio = 23/15/62% Other compounds of oat grain Shewry PR, Piironen V, Lampi A-M, Nystrom L, Li L, Rakszegi M, et al. Phytochemical and fiber components in oat varieties in the HEALTHGRAIN diversity screen. J Agric Food Chem. 2008;56:9777-84. Depends on botanical/animal origin and/or processing) I. Bioaccessibility (Depends on physical and physicochemical properties of food matrix) Macro-, micro-and phyto-nutrients III. Metabolic effects (Depends on site of action and metabolization degree) II. Absorption (depends on absorption site and physiological parameters such as transit time) IV. Health effects (Depends on initial health status of the subject) One has gradually moved from a technology that was adapted to the food to the food that has adapted to technology For example, bread has gradually adapted to the technological requirements: -Selection of wheat on protein content for baking process -Adding vital gluten and enzymes to improve the bread and the structural integrity of industrial products -Kneading conditions: long and intensive → airy bread with high GI -Yeast: short fermentation → loss of the benefit of the leavened enzymes -Adding salt to tasteless food Save time, price, and conservation time A bread of poor nutritional quality and unnatural taste Cereal products versus processing: who is first? Cereals & processing: towards a more meaningful ranking A new food classification based on degree of processing: bioavailability: particle size Holt SH, Miller JB. Particle size, satiety and the glycaemic response. Eur J Clin Nutr 1994;48:496-502. Diet based on cereal products with different particle sizes Physical structure and satiety potential Holt SH, Miller JC, Petocz P, Farmakalidis E. A satiety index of common foods. Eur J Clin Nutr 1995;49:675-90. Moorhead SA, Welch RW, Barbara M, Livingstone E, McCourt M, Burns AA, Dunne A. The effects of the fibre content and physical structure of carrots on satiety and subsequent intakes when eaten as part of a mixed meal. Brit J Nutr 2006;96:587-95. GB, Heaton KW, Murphy D, Burroughs LF. Depletion and disruption of dietary fibre. Effects on satiety, plasma-glucose, and serum-insulin. Lancet 1977;2:679-82. Physical structure and satiety potential Apple  Purée  Juice Satiety Insulin Physical structure and satiety (The fullness factor) http://nutritiondata.self.com/topics/fullness-In the sciences, application of methodological reductionism attempts explanation of entire systems in terms of their individual, constituent parts and their interactions"

(•

  Best et al. The Lipotropic effect of protein. Nature. 1935;135:821-822) Main lipotropes: choline, betaine, myo-inositol, méthionine and carnitine • Minerals and vitamins: -B vitamins (niacin, pantothenic acid and folates) -Magnesium -Tocotrienols (mainly a and g)?

•-

  Fermentation is a biochemical reaction of the conversion of the chemical energy contained in a carbon source (often glucose) into another form of energy directly usable by the cell in the absence of oxygen (anaerobic conditions) • Little used in the West for grains products Poutanen et al. Sourdough and cereal fermentation in a nutritional perspective. Food Microbiology 2009;26:693-9 : sourdough bread… • Widely used in the traditional diet of the developing countries on the grains and seeds, mainly Africa, Asia and South America Nout MJR. Rich nutrition from the poorest -Cereal fermentations in Africa and Asia. Food Microbiology 2009;26:685-92. • Maize: mawé (Bénin and Togo), kenkey (Ghana)… • Sorghum: tchoukoutou (beer in Bénin and Togo), uji (porridge)… • Millet: ben-saalga (Burkinabe gruel), jnard (Himalayan beer)… • Rice: idli (India), mifen (Chinese rice noodles)… • Legumes: wadi, dhokla… Pre-fermentation, germination and soaking kenkey tchoukoutou idli uji Pre-fermentation, germination and soaking • Increasing protein digestibility • Increasing levels of macro-, micro-and bioactive phyto-nutrients: • B vitamins: riboflavins, thiamine, folate ... • Exo-polysaccharides (prebiotics): e.g., gluco-and fructo-oligosaccharides • Resistant starch • Free polyphenols • Small bioactive peptides and free amino acids • Solubilization of fiber: Arabinoxylans • Degrading phytic acid: increased mineral bioavailability • Increasing energy density • Improving texture, flavor and palatability • Changing the properties of the fibrous complex • Reducing glycemic and insulinemic responses • Allergen reduction • Increasing antioxidant potential • ... The discovery of fire (from -400 000 BC to -1,7 Millions years)  The Neolithic (-9000 BC): sedentarisation and huge increase of grain consumption including cereals  The invention of the steam engine (1769) and the industrial era (1800-1970) The onset of ultra-processed foods (1980-today)  A new nutritional transition: from ultra-processed foods to sustainable diets From mostly vegetable foods and little processed to ultra-processed, fractionated, recombined, refined and high-energy foods -More or less rapid according to countries Increased physical inactivity and sedentariness: -Consumed energy > spent energy -Weight gain A lack of nutritional education : -Preventive nutrition research is recent -Ignorance causes bad choices -Ignorance makes us more vulnerable to advertising pressure The reductionist approach pushed to the extreme: -Application to nutritional research (preventive) -Yet human nutrition is a holistic science Grain products vs obesity/overweigth

   b-glucan fermentation could contribute to the hypocholesterolaemic properties b-glucan may slow the rate of starch digestion and help increase the resistant starch content (favors butyrate production, an anti-carcinogenic compound)

5 .

 5 The clear evidence on the cardio-vascular benefits represented by oats should encourage the development of more oat-based products." N = 21 eligible randomized controlled trials A summary of some of the human studies investigating the effect of oat-based products on

1) liquid oat-based foods seems to be more consistent in decreasing levels of cholesterol than semi-solid or solid foods where results are more heterogeneous ; 2 )

 2 the molecular weight of β-glucans, but also their quantity, probably play a role on cholesterol reduction ; 3) natural β-glucan-rich oat based foods would have different effect on lipemia than added β-glucans as isolated ingredients. A summary of some of the human studies investigating the effect of oat-based products on lipemia Conclusions Oat products & health: A literature review Hypertension Maki, K. C., R. Galant, et al. (2007). "Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure." European Journal of Clinical Nutrition 61(6): 786-795. The results of the present trial suggest beneficial effects of foods containing b-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects. The oat b-glucan group received (1) a ready-to-eat (RTE) cold cereal made with oat bran, (2) oatmeal and (3) a powdered form of oat b-glucan. Control: maltodextrin. Consumption of oatmeal by children was associated with better nutrient intake, diet quality, and reduced risk for central adiposity and obesity and should be encouraged as part of an overall healthful diet Compared to nonconsumers, oatmeal consumption was associated with a 40% lower risk of being obese and a 64% lower risk of having an elevated WC Oat products & health: A literature review Glycaemia and insulinaemia Tosh, S. M. (2013). "Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products." European Journal of Clinical Nutrition 67(4): 310-317.

  Oat products & health: A literature review HbA1c, fasting glucose & insulin sensitivityHe LX, Zhao J, Huang YS, Li Y. The difference between oats and beta-glucan extract intake in the management of HbA1c, fasting glucose and insulin sensitivity: a meta-analysis of randomized controlled trials. Food & Function. 2016;7:1413-28. Higher consumption of whole oats and oat bran, but not oat beta-glucan extracts, are associated with lower HbA1c, fasting glucose and fasting insulin of T2D, hyperlipidaemic and overweight subjects, especially people with T2D.

(USDA database) g/100 g Water Carbohydrates Proteins Lipids Fiber Ash

	Oat	8.2	66.3	16.9	6.9	10.6	1.7
	Wheat	12.8	68.0	15.4	1.9	12.2	1.9
	Maize	10.4	74.3	9.4	4.7	7.3	1.2
	Barley	9.4	73.5	12.5	2.3	17.3	2.3
	Rice (brown)	10.4	77.2	7.9	2.9	3.5	1.5

source of lipotropes Cereals as a source of lipotropes

	mg/100 g fresh	Choline Betaine	mg/100 g fresh
	product			product
	Whole cereals	40	183
	Leguminous seeds 80	1
	Vegetables	17	23
	Nuts and seeds	49	4
	Fruits	8	0.2
	Beverages	12	1.4

-

Cobalamine: B12 (can be found in PBF, e.g. supplied by yeast in some cereal products) -Taurine

Different and/or common physiological mechanisms

Cereals as a

Methionine Myo-inositol Whole cereals 197 37 Leguminous seeds 285 65 Vegetables 35 22 Nuts and seeds 356 20 Fruits 10 61 Beverages 8 The lipotropic vs antioxidant package Physiological mechanism involved Bioactive compounds

 Antioxidant protection (n  34) (numerous diseases associated with increased oxidative stress: obesity, diabetes, CVD, cancers,…) Lipotropic protection (n  23) (fatty liver associated with alcohol excess, obesity/overweight, diabetes/insulin resistance, steatohepatitis/fibrosis/cirrhosis) Reduced glutathione, methionine, cystine, lignins, phytic acid, magnesium, iron, zinc, manganese, copper, selenium, thiamine, riboflavin, tocopherols, tocotrienols, b-carotene, lutein, zeaxanthin, bcryptoxanthin, phenolic acids, flavonoids, lignans, alkylresorcinols, betaine, choline, policosanol, melatonin, g-oryzanol, avenanthramides, saponins

Betaine, choline, methionine, myo-inositol, carnitine, magnesium, niacin, pantothenic acid, folates, flavonoids, phenolic acids, lignans, saponins, fibre, lignins, phytic acid, phytosterols, alkylresorcinols, oligosaccharides, poly-unsaturated fatty acids (e.g. CLA), short-chain fatty acids (e.g. acetic acid and propionic acid), melatonin, PUFA

Different but complementary physiological modes of action

Harmful or side-effects of one compound at high dose Natural versus added fiber Monro, J., Mishra, S., Redman, C., Somerfield, S., Ng, J., 2016. Vegetable dietary fibres made with minimal processing improve health-related faecal parameters in a valid rat model. Food

Funct 7, 2645-54.

summary of some of the human studies investigating the effect of oat-based products on lipemia Intervention studies

  Anthony Fardet; S. Tosh; Peter Wilde. Processing of oat: impact on its health benefits. To be submitted.

	Myriam Grundy; References	Process	Oat-based products	Total	LDL-	Triglycerid
				cholesterol	cholesterol	es (%)
			Yeast-leavened oat bran breads	NS (%)	NS (%)	nd	Solid
			containing β-glucan of low or high
		Fermenta	average molecular weight
	Kerckhoffs et al. (2003) Zhang et al. (1992)	tion	Oat bran bread Oat bran bread	NS -11	NS -15	nd nd	Solid Solid
	Bremer et al. (1991) Reyna-Villasmil et al.	/baking	Oat bran bread Oat bran bread	-4 (NS) -16	-11 (NS) -28	NS NS	Solid Solid
	(2007)
	Bartram et al. (1992)		Oat bran cereal muesli	-11	-11	nd	Solid
	Maki et al. (2010)		Whole-grain ready-to-eat oat cereal	-9	-5	NS	Solid
	Pins et al. (2002) Anderson et al. (1990)	Breakfast	Oatmeal and ready-to-eat cereals Oat-bran cereal (flake, biscuits or ready-	-15 -5	-16 -9	nd nd	Solid Solid
		oat	to-eat cereals)
	Marlett et al. (1994)	cereals	cereals Oat bran-forms used as hot or cold		nd	nd	Solid
	Gold et al. (1991)		Ready-to-eat oat bran cereals and snack	NS	NS	nd	Solid
			bars

A

Texture Romero et al. (1998) 64 Ultra- processed (fractiona tion/reco mbinatio n)

		Cookies enriched with oat bran	nd	-26	NS	Solid
	Amundsen et al. (2003) 65	Premade diet containing oat bran	-6	-9	nd	Solid
		concentrate in 8 products
	Bindu & Krishnaveni	Oats porridge	NS	-8	NS	Semi-solid
	(2013) 66

Beer et al. (1995) 67

			Oat gum instant whip	NS	NS	NS	Semi-solid
	Naumann et al. (2006) 68		β-Glucan incorporated into a fruit drink	-3	-5	NS	Liquid
	Biorklund et al. (2005) 52		Beverages with beta-glucans from oats	-7	-6	NS	Liquid
	Onning et al. (1999) 69		Oat milk	-6	-6	NS	Liquid
	Onning et al. (1998) 70	Beverages	Oat milk	-4	-9	nd	Liquid
	Martensson et al. (2005) 71		Fermented, ropy, oat-based products	-6	-6	nd	Liquid
	Kerckhoffs et al.		Oat bran in orange juice	-4	-7	nd	Liquid
	(2003) 54 ???

1) Monteiro CA, Cannon G, Moubarac JC, Martins AP, Martins CA, Garzillo J, Canella DS, Baraldi LG, Barciotte M, et al. Dietary guidelines to nourish humanity and the planet in the twenty-first century. A blueprint from Brazil.

Rebello CJ, O'Neil CE, Greenway FL. Dietary fiber and satiety: the effects of oats on satiety. Nutr Rev. 2016;74:131-47.

Human studies 2.1 Cardiovascular diseases and their risk factorsOat is anti-atherogenic, hypolipidemic (TG, LDL-chol and cholesterol), hypotensive

Ruxton CHS, Derbyshire E. A systematic review of the association between cardiovascular risk factors and regular consumption of oats. British FoodJournal. 2008;110:1119-32.

Evans CEL, Greenwood DC, Threapleton DE, Cleghorn CL, Nykjaer C, Woodhead CE, et al. Effects of dietary fibre type on blood pressure: a systematic review and meta-analysis of randomized controlled trials of healthy individuals. Journal of Hypertension. 2015;33:897-911.

Human studies 2.2 Type 2 diabetes and its risk factors

O'Neil CE, Nicklas TA, Fulgoni VL, DiRienzo MA. Cooked oatmeal consumption is associated with better diet quality, better nutrient intakes, and reduced risk for central adiposity and obesity in children 2-18 years: NHANES 2001-2010. Food & Nutrition Research. 2015;59.

2.3 Cancers & overall mortalityBoffetta, P., F.Thies, et al. (2014). "Epidemiological studies of oats consumption and risk of cancer and overall mortality." British Journal of Nutrition 112(SupplementS2): S14-S18.

RR = 0•91 (95% CI 0•81, 1•02) in men RR = 0•97 (95% CI 0•84, 1•11) in women

The concept of fiber co-passengers Vitaglione, P., Napolitano, A., Fogliano, V., 2008. Cereal dietary fibre: a natural functional ingredient to deliver phenolic compounds into the gut. Trends in Food Science and Technology 19, 451-463.

Fermented oat

Bei Q, Liu Y, Wang L et al. (2017) Improving free, conjugated, and bound phenolic fractions in fermented oats (Avena sativa L.) with Monascus anka and their antioxidant activity. Journal of Functional Foods 32, 185-194.

• Oats soaked in water for 6 h before being used for fermentation • Fermentation substrate was prepared with oats (20 g), glycerinum (1.6 g), yeast extract (0.4 g), and water added to a 60% moisture content and then sterilized by autoclaving at 115 °C for 30 min and cooled for inoculation. • The sterilized fermentation substrate was inoculated with a spore solution (105 spores/g of oat) in a 250-mL Erlenmeyer flask containing 20 g of oats and was incubated at 30 °C for 14 day. A total of 18 hypertensive and hyperinsulinemic ( ≥10 μU/mL) men and women

The addition of oat cereals to the normal diet of persons with hypertension significantly reduces both systolic and diastolic blood pressure. Soluble fiber-rich whole oats may be an effective dietary therapy in the prevention and adjunct treatment of hypertension.

Oat cereal group (standardized to 5.52 g/day beta-glucan) Versus Low-fiber cereal control group (less than 1.0 g/day total fiber) Anti-inflammatory effects of oat b-glucans are associated with its ability to reduce the number of lymphocytes T and B and granulocytes, promote leukocyte infiltration in intestinal mucosa, lower the production of pro-inflammatory enzymes and cytokines and stimulate the release of antiinflammatory cytokines.

Oat products & health

The anti-inflammatory properties of oat b-glucans seem to be related with its molecular weight, but the available data are contradictory.

Conclusions & Perspectives

Reductionist versus holistic view of cereals:

-From the nutrient approach to complex whole food approach

The neglected role of oat food structure/matrix effect:

- • The Three Golden Rules for healthy, sustainable and ethical diet to protect health, animal welfare and environment:

-85/15% plant/animal calories : Replacing animal calories by grain calories -85/15% minimally-/ultra-processed foods -Among minimally-processed foods diversify based on local, seasonal and organic foods when possible

Conclusions & Perspectives

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Tobias Regner
email: tobias.regner@uni-jena.de

Paolo Crosetto

The experience matters: participation-related rewards increase the success chances of crowdfunding campaigns

Keywords: JEL classifications: L26, D03, G32 crowdfunding, entrepreneurial finance, donations, reward levels, identity, self-image, social-image

Crowdfunding recently emerged as an alternative funding channel for start-ups, creative artists and social endeavors. On specialized web platforms, project creators ask the crowd for support and provide in return a set of rewards, modulated according to the amount of support pledged. Our study investigates the role of self-and social-image enhancing rewards in determining project success. Using data from 346 projects hosted by Startnext, the biggest crowdfunding platform in Germany, we show that providing higher shares of reward levels that let pledgers participate in and experience the project is correlated with project success.

Introduction

Reward-based crowdfunding recently emerged as an alternative funding channel for entrepreneurs, creative artists and social projects. Beside the option to simply donate money, project creators often provide rewards: products or services promised in exchange for pledging a specific amount. Projects differ in the number, nature, and monetary requirements of the reward levels offered. A typical project features 'cheap' levels delivering a thank-you note or small gadget, 'medium' levels providing the full product, invitations to events or more elaborated gadgets (notably merchandising), and 'expensive' levels with exclusive or all-comprehensive offers. Levels are usually nested, with the more expensive ones including all rewards of cheaper ones, plus some extra.

Project-level determinants of crowdfunding projects have already been studied and some robust stylized facts emerged: quality signals like the project's communication with pledgers [START_REF] Mollick | The dynamics of crowdfunding: An exploratory study[END_REF][START_REF] Kromidha | Social identity and signalling success factors in online crowdfunding[END_REF][START_REF] Gafni | Are the life and death of an early stage venture indeed in the power of the tongue? lessons from online crowdfunding pitches[END_REF] or the creator's social capital [START_REF] Mollick | The dynamics of crowdfunding: An exploratory study[END_REF][START_REF] Massimo | Internal social capital and the attraction of early contributions in crowdfunding[END_REF] increase chances of success. However, little is known about the impact of the reward structure. While [START_REF] Frydrych | Exploring entrepreneurial legitimacy in reward-based crowdfunding[END_REF] find no correlation between the number of reward levels and project success, [START_REF] Simons | Which reward should i choose? preliminary evidence for the middle-option bias in reward-based crowdfunding[END_REF] provide evidence that the cognitive bias for the middle option affects choices among rewards.

In this paper we look beyond such quantitative/design aspects and into the role played by the type of reward in mobilizing pledgers. We categorize reward levels based on the concept of identity [START_REF] Tajfel | An integrative theory of intergroup conflict[END_REF], introduced by Akerlof and [START_REF] George | Economics and identity[END_REF] into economic modeling: behavior in line with one's identity results in positive utility, while behavior in contrasts with it has negative effects.

The role of identity-building is crucial in crowdfunding. [START_REF] Gerber | Crowdfunding: Why people are motivated to post and fund projects on crowdfunding platforms[END_REF] find that funders are motivated by feelings of connectedness to a like-minded community in interviews at three crowdfunding platforms and [START_REF] Belleflamme | Crowdfunding: Tapping the right crowd[END_REF] stress that "the crowd must identify themselves as such."

We hypothesize that such an identity/community feeling of crowdfunders can be supported by rewards that strengthen the relationship between the crowd and the project creator. Rewards can enhance the self-image of the pledger as a member of the community. Self-image-enhancing rewards are meant for the pledger only. Examples are postcards or individualized services/products. Projects can also use their reward structure to create appeal for funders with social-image concerns [START_REF] Bénabou | Incentives and prosocial behavior[END_REF][START_REF] Ellingsen | Pride and prejudice: The human side of incentive theory[END_REF][START_REF] Andreoni | Social image and the 50-50 norm: A theoretical and experimental analysis of audience effects[END_REF]. Supporting new products/services -and showing this to others -boosts the social reputation of some individuals and, in turn, translates into an increased willingness to spend. Examples of social-image rewards are special thanks at the end of a movie or being mentioned as donor on the project web site. Rewards levels can also cater to both social-and self-image at the same time. This is the case of invitations to special project-related events (e.g. a meet&greet) or clothing conveying the community membership (t-shirts, bags, etc.).

We use data from Startnext to assess the role of reward levels and types in project success. Startnext is the biggest reward-based crowdfunding platform in Germany, with 37 millions e raised by January 2017. 1 We merge individual pledge data and product characteristics obtained from Startnext with a manual categorization of the self-and social-image aspects of reward levels. Our final dataset consists of 346 projects (186 successful), for a total of 785 thousand e raised.

Results show that projects offering a higher number of rewards appealing to the crowd's identity, specifically offering ways for pledgers to actively participate in the project, have a positive impact on success.

Data Set

We obtained a fully anonymized database dump from Startnext. Startnext projects have a page on the platform featuring the funding target, duration time, a text description, a pitch video and pictures. All projects have a blog for updates and to communicate with the public. At any moment, the page displays the remaining time, the current funding level (as a % of the target) and number of supporters. Project creators can choose funding durations of 5 to 90 days.

The data, described in more detail in [START_REF] Crosetto | It's never too late: funding dynamics and self-pledges in crowdfunding[END_REF], contain all transactions on the platform from the date of its launch in October 2010 to February 10th, 2014. The dataset consists of 2,713 projects. Out of those, 2,254 got enough fans to reach the funding phase2 and 1,139 were successfully funded. For each project we have the following variables (averages in parentheses): funding duration (54 days), target amount (6,194 e), whether the project has been featured on Startnext's home page (8.3%), number of words (half a page), videos (1.1), images (7.6) on the project page or blog, number of entries on the project blog (4), its number of fans (79.6) and the projects' category. The most popular project categories are movies (31.6%), music (25%), event (11.6%) and cultural education (11.1%).

The reward level structure was not part of the data dump. We hence manually gathered information from the individual web pages of 346 randomly picked individual projects -roughly 15% of the total sample. For each project belonging to our random sample, we collected all the reward levels and the corresponding amounts needed to unlock the reward. We then categorized the reward levels with respect to the visibility of the pledger's support: rewards can appeal to the pledgers' self-and/or socialimage concerns. Levels that facilitate the pledgers' identification with the project are categorized as self-image only. We require them to help pledgers remember being part of the project, to have limited public visibility, and to be tangible/physical. Examples are postcards or stickers. The announcement of the pledger's name in a situation with public exposure (e.g., being mentioned as a donor in the booklet/credits, on a social media platform, the project web site) is regarded as a social-image only reward. Some reward levels have both self-and social-image appeal. The nature of the reward itself can nonetheless vary within this category. Project merchandising (e.g., t-shirts, bags) facilitates pledgers' identification with the project but since it also conveys the pledgers' support to the public we treat it as having both self-and social-image characteristics. Being publicly part of the project, for instance, as an extra in the movie, after show backstage access, a meet&greet, also relates to self-as well as socialimage, but with a different type of involvement, as it gives the pledger an enhanced sense of community and participation. Thus, we base our analysis around four main types of rewards: social-image only, self-image only, and two types of combined self-and social-image rewards: active participation in the project and merchandising. For each of these types we compute its relative importance among all reward levels of a project.

Self-image only rewards account for 36% of all levels, participation for 24%, social-image only 11% and merchandising 10%.3

Results

Table 1 reports marginal effects of four different regression specifications. Column 1 reports a probit regression of project success on its main determinants. It is run on the full Startnext dump of 2,254 projects and is given for reference. Columns 2 to 4 report probit regressions on the reward levels sample of 346 projects. Column 2 uses the same specification of column 1, without any reference to reward levels. Column 3 provides a supply-side analysis of the impact on project success. Variables reflect the share of each type of level, irrespective of the amount of pledgers that chose them. Column 4 includes instead a demand-side analysis. Variables reflect the share of pledges gone to levels belonging to each category; the relative success (or failure) of each level is thus taken into account. However, levels requiring higher amounts of money have by construction a bigger impact on the likelihood of success, conditional on being chosen. Columns 3 and 4 hence complement each other. All columns include the full set of category dummies (music, games, technology, etc.) Standard errors in parentheses. * p < 0.10, * * p < 0.05, * * * p < 0.01 a . 10 projects are dropped since they collected zero pledges and shares cannot be properly computed.

Table 1: Marginal effects for the reference dataset and different specifications on the reward-level dataset Columns 1 and 2 replicate the main stylized facts from the literature. For the whole Startnext database (column 1) success is more likely for less ambitious projects with shorter funding durations;

for projects that invest in communication of any form especially videos and news updates via the blog;

the more fans a project attracts; for projects featured on the Startnext home page. When looking at the category dummies (not shown), music projects are significantly more likely to succeed, while invention, literature, design and games projects less so.

Most of these findings translate to our smaller sample of 346 projects (column 2). Notable exceptions are image count, which plays a role in the restricted but not in the larger sample; and video count and recommendation by Startnext that, though showing the same sign and similar magnitude, do not reach significance in the smaller sample.

Adding our self-and social-image categorization reveals that increasing the share of participation rewards is correlated with project success, all other determinants staying the same. This is true both when looking from the supply side -including the share of offered reward levels entailing participation in the project -and from the demand side -taking into account the actual choices of pledgers.

more crowd support and increases the probability of project success. In particular, since the average project has about 10 reward levels, out of which 2.5 are participation rewards, adding one participation reward is predicted to increase the likelihood of success by 3%.

Discussion

What determines the success of campaigns in reward-based crowdfunding? Previously, studies have identified the importance of conveying the quality of a project and its respective creator. Communication with the crowd has repeatedly been found to influence funding success [START_REF] Mollick | The dynamics of crowdfunding: An exploratory study[END_REF][START_REF] Kromidha | Social identity and signalling success factors in online crowdfunding[END_REF][START_REF] Gafni | Are the life and death of an early stage venture indeed in the power of the tongue? lessons from online crowdfunding pitches[END_REF] and also the size of the project creator's personal network matters [START_REF] Mollick | The dynamics of crowdfunding: An exploratory study[END_REF][START_REF] Massimo | Internal social capital and the attraction of early contributions in crowdfunding[END_REF].

What else can project creators do to increase their chances of funding success? We find that the structure of the reward levels is another important channel for the creator to attract potential pledgers.

Projects that offer a higher share of reward levels providing enhanced participation possibilities have a higher probability of success. This includes being an extra in the movie, after show backstage access or a meet&greet with the creator of the project. This result is robust to controlling for the fact that those reward levels are usually the most expensive, thus contributing per se more to project success.

Our finding further supports the intuition that one of the key tasks of crowdfunding project creators is to create a feeling of community around the project, and sustaining this feeling during the whole campaign [START_REF] Gerber | Crowdfunding: Why people are motivated to post and fund projects on crowdfunding platforms[END_REF][START_REF] Belleflamme | Crowdfunding: Tapping the right crowd[END_REF]. We provide evidence that pledgers' identity concerns can be mobilized via the reward level structure. While self-/social-image concerns are also triggered by other reward level types (public credits for support, merchandising or simply an item that facilitates remembering support), we only find evidence for an effect when pledgers participate in the ongoing crowd effort in a more literal sense. It seems that it is more the actual experience of being part of the project than showing support (on a bag or t-shirt) or being publicly mentioned as a supporter that has a not negligible impact on the likelihood of success.

  as control. All results are robust to the exclusion of category dummies.

		Full Startnext sample	Project level analysis	Offered levels	Chosen levels
		Project success	Project success	Project success	Project success
		coeff.	st.err	coeff.	st.err	coeff.	st.err	coeff.	st.err
	Funding Duration Target amount (1000e) Total number of fans Featured on main page	-0.0029 * * * -0.1075 * * * 0.0091 * * * 0.4741 * * *	(.0005) (.0137) (.001) (.1012)	-0.00220 -0.0958 * * * 0.00930 * * * 0.291	(0.00137) (0.0179) (0.00153) (0.229)	-0.00242 * -0.0985 * * * 0.00925 * * * 0.315	(0.00139) (0.0184) (0.00158) (0.227)	-0.00237 -0.0960 * * * 0.00851 * * * 0.323	(0.00145) (0.0185) (0.00156) (0.229)
	Word count (100) Video count Image count Blog entries	0.0068 0.0213 * * 0.0019 0.029 * * *	(.0045) (.0085) (.0026) (.0042)	-0.00103 0.0477 0.0234 * * * 0.0350 * * *	(0.0120) (0.0315) (0.00812) (0.0102)	-0.00244 0.0462 0.0229 * * * 0.0377 * * *	(0.0122) (0.0322) (0.00824) (0.0106)	-0.00353 0.0532 0.0223 * * * 0.0333 * * *	(0.0123) (0.0327) (0.00820) (0.0104)
	Analysis of reward levels
	Number of reward levels			-0.00487	(0.00873)	-0.00369	(0.00879)	-0.00499	(0.00890)
	Offered levels
	Self image only					0.00332	(0.00257)
	Social image only Self+social: participation					0.00263 0.00361 * *	(0.00167) (0.00179)
	Self+social: merchandising					0.00161	(0.00212)
	Chosen levels
	Self image only							0.000786	(0.00206)
	Social image only Self+social: participation							0.000176 0.00339 * *	(0.00124) (0.00156)
	Self+social: merchandising							0.000959	(0.00205)
	N	2,254		346		346		336 a
	pseudo-R 2	0.336		0.341		0.353		0.345

Startnext employs the threshold pledge model, as Kickstarter. If pledges reach the target amount by the deadline, the project is funded and pledges are paid; else, no transaction takes place.

Projects have to reach a minimum level of fan support to go public on the website. For details see[START_REF] Crosetto | It's never too late: funding dynamics and self-pledges in crowdfunding[END_REF].

This classification does not cover all levels, since some do not entail any actual reward and are outright donations. Others offer unrelated services with no self-or social-image impact.

grateful to Startnext, especially Anna Theil, for providing the data and helpful discussions. We would like to thank audiences in Mannheim and Jena for feedback. Daniel Meyer and Javier Changoluisa provided excellent research assistance. Tobias Regner gratefully acknowledges support by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)project number 628902.