Oulmann Zerhouni

Laurent Bègue

SEE PROFILE

Keywords: alcohol sponsorship, self-regulation failure, evaluative learning, implicit attitudes

Background:

We tested whether incidental exposure to alcohol marketing messages in sporting events (i) influenced automatic evaluation of brands and alcohol in general and (ii) if these processes occur through deliberative (conscious) or nonconscious processes.

Methods: Using an experimental design, participants watched a sport event containing (i) a prototypical alcohol brand, or (ii) a brand unrelated to alcohol (iii) or a non-prototypical alcohol brand. One hundred and nine participants were randomly assigned to either a cognitively depleting task to impair motivation for effortful conscious processing before watching the excerpt, or a control task. We measured indirect (implicit) and direct (explicit) attitudes toward alcohol and brands, and self-report measures assessing affective response toward the event, involvement in processing the message and identifications toward the playing teams.

Results:

We found a positive main effect of incidental exposure to alcohol brands on indirect measures of attitudes toward alcohol as well as the specific brand. No effect of cognitive fatigue on indirect measure toward brands and alcohol was observed.

Conclusion:

Incidental exposure to alcohol marketing messages appear to impact indirect measures of attitudes toward the brand and alcohol in general, and seems to rely on nonconscious automatic processes.

Background

Alcohol consumption is responsible for 3.2% of worldwide deaths and is ranked fourth in terms of disability adjusted life years [START_REF]Global Status Report on Alcohol and Health[END_REF]. Accordingly, reducing alcohol consumption is a public health priority, particularly in groups where excessive alcohol consumption appears most problematic (e.g., young adults, sport participants) [START_REF] O'brien | Alcohol industry sponsorship and hazardous drinking among sportspeople[END_REF]. Despite evidence showing that direct alcohol sponsorship of sports participants is associated with more hazardous drinking [START_REF] O'brien | Alcohol industry sponsorship and hazardous drinking among sportspeople[END_REF][START_REF] O'brien | Alcohol industry and nonalcohol industry sponsorship of sportspeople and drinking[END_REF], and that large numbers of children are exposed to alcohol sponsorship messages when watching sport (4), the alcohol industry remains a leading sponsor of sport, accounting for 20% of all sport sponsorships [START_REF] O'brien | Alcohol advertising in sport and non-sport TV in Australia during children's viewing times[END_REF][START_REF] Maher | Patterns of sports sponsorship by gambling, alcohol and food companies: an Internet survey[END_REF]. The frequent incidental and/or unattended exposures to brands and branded products such as alcohol, are difficult to consciously process and are therefore difficult to consider and critically assess/filter in a deliberative manner [START_REF] Rehm | Alcohol and sponsorship in sport: some much-needed evidence in an ideological discussion[END_REF][START_REF] Demars | Stadium signs on television: The television viewers recall of in-stadium advertisements during a televised sporting event[END_REF]. Research already shows that brand recall is higher when branding (e.g., banners, logos) have been visually present for a long period of time [START_REF] Demars | Stadium signs on television: The television viewers recall of in-stadium advertisements during a televised sporting event[END_REF], and when the frequency of exposure is high [START_REF] Correia | Sponsorship effectiveness in professional sport: an examination of recall and recognition among football fans[END_REF]. However, frequent incidental and unattended brand exposures (e.g., branding on stadium signage) may have a similar impact on brand memory and attitudes to the branded product (e.g., Heineken Beer), through unconscious or implicit processing. Because advertising stimuli are generally presented peripherally to the in-game action (i.e., the sporting event), two questions arise: (i) does processing of this type of advertising incur cognitive costs? and (ii) does attitude change toward a brand automatically generalizesor "spillovers"to a broader category of stimuli, that is, alcohol?

There is indeed recent experimental data that have shown that incidental exposure to alcohol sponsorship and associated messages in sporting contexts influences indirect measures of attitudes (i.e., relatively automatic and nonconscious evaluations) toward the sponsor's alcohol brand, and to some extent toward alcohol generally [START_REF] Zerhouni | Dynamic exposure to alcohol advertising in a sports context influences implicit attitudes[END_REF]. However, the question of how sponsorship influence occurs remains of primary relevance for public health, as it informs us of the potential impact of large advertising campaigns on attitudes toward alcohol and consumption when they are based on implicit and involuntary processes.

Since indirect measures of attitudes are excellent predictors of alcohol consumption [START_REF] Wiers | Cognitive Bias Modification and Cognitive Control Training in Addiction and Related Psychopathology: Mechanisms, Clinical Perspectives, and Ways Forward[END_REF] and predict unique variance compared to direct measures [START_REF] Rooke | Implicit cognition and substance use: a metaanalysis[END_REF], this paper aims to illuminate whether the effects of alcohol sponsorship on these alcohol-related attitudes can occur completely automatically, or, on the contrary, would be mediated by deliberative processes.

Second, we examined whether changing attitudes towards a specific brand would have an impact on the general concept of alcohol (i.e., spillover).

To What Extent Does the Viewer Voluntarily Process Advertising and Branding

Stimuli Onscreen?

As mentioned above, promotion of alcohol products is sometime found in contexts where one would a priori expect it not to be there. Even outside stadiums, exposure to advertising in US urban areas show a link between exposure to alcohol in the media and an increase in alcohol consumption, while lowering the age at which children and adolescents are likely to start drinking [START_REF] Anderson | Special issue: The message and the media: Impact of alcohol advertising and media exposure on adolescent alcohol use: A systematic review of longitudinal studies[END_REF]. It is therefore essential to identify the processes that will lead individuals to drink alcohol, as to develop prevention and intervention procedures that will limit the harmful consequences and costs for public spending.

It has been argued that branded promotion incidentally presented during an event are likely to be more effective than regular advertising due to a strong emotional and cognitive engagement of the viewer toward the event [START_REF] Harvey | Measuring the effectiveness of true sponsorship[END_REF]. On the other hand, several studies showed that individuals under cognitive load (i.e., performing a demanding, secondary task, while doing a primary task) would be less sensitive to external influences (e.g., [START_REF] Pleyers | Evaluative conditioning may incur attentional costs[END_REF]. This suggests that to be effective, advertisement would require cognitive resources. One of the central issues is therefore whether encoding depends upon conscious engagement into brand memorization and attitude change.

Under Which Conditions Does Exposure to Sponsor Brands and Advertising Lead to Broader Conceptual Generalizations? Spillover Effect from a Brand to a Broader Category.

From a cognitive point of view, recent data have highlighted that the evaluation of a single stimulus can be generalized to a broader category of stimuli if it shows salient cues of membership of this category, and when the number of distracting stimuli is not too high as to allow the relevant indices to be treated [START_REF] Hütter | What is learned from repeated pairings? On the scope and generalizability of evaluative conditioning[END_REF]. Therefore, during the formation of the evaluation, the initial emotional reaction should be transferred not only to the target (i.e., the brand Heineken), but also to a superordinate category related to the brand (e.g., alcohol, beer). In order to maximize the effects of evaluative learning from a stimulus toward a general category, the alcohol brand must have strong associations in memory with the superordinate concept through links with affective, perceptual and sensory-motor components [START_REF] Schröder | The affective meanings of automatic social behaviors: three mechanisms that explain priming[END_REF]. Therefore, attitude change toward prototypical, well-known, exemplars of a category should lead to a stronger generalization to other exemplars of this category, and the category itself.

Introduction and hypothesis.

Manipulation of cognitive resources

We aimed, first, to determine whether sponsor branding influence on participant's attitudes incurs effortful cognitive activity. In this study, we reduced participants' abilities to draw on self-regulatory resources prior to viewing the excerpts by using an ego-depletion task. An ego-depletion task typically consists in reducing volitional processing at time 2 (here, exposure to sponsorship) by asking the participant to perform a cognitively demanding task at time 1 [START_REF] Hansen | Vagal influence on working memory and attention[END_REF]. Recent conceptualization has shown that impairing self-control tends to also reduce executive and cognitive control in a broader sense, which is particularly efficient on tasks requiring motivation to engage in a task requiring some amount of mental effort [START_REF] Hofmann | Executive functions and self-regulation[END_REF][START_REF] Hagger | Ego depletion and the strength model of self-control: a meta-analysis[END_REF][START_REF] Dang | The ego could be depleted, providing initial exertion is depleting: A pre-registered experiment of ego depletion[END_REF]. Furthermore, impairing self-regulation is close to what an individual might experience as external pressures in daily life situations, in which one is more likely to have limited resources to and be targeted by multiple external demanding tasks that hinder selfcontrol.

Manipulation of the Spillover Effect

Second, we hypothesize that the more representative the brand is of the alcohol concept in memory, the more the latter will be activated, and the stronger the 'spillover' effect.

Evaluative change toward a single stimulus can be generalized to a category of stimuli if it shows clear evidence of belonging to a broader category when the number of distracting stimuli is not too high to allow relevant cues to be processed. In order to maximize the effects of associative learning from a stimulus to a general category (i.e., spillover), the stimulus must have strong associations in memory with the overordered concept, i.e., the more the participant experiences it, the stronger the spillover effect will be. Therefore, participants were exposed to (i) sport excerpts for the "Heineken" brand (very prototypical for French participants) or (ii) the "Steinlager" brand (a New Zealand beer brand, not prototypical for French participants) or (iii) the "Castrol Edge" brand (unrelated to alcohol).

We predict that indirect measures of attitudes toward alcohol in general should be more positive for individuals exposed to the "Heineken" brand compared to the "Steinlager" brand and "Castrol Edge".

Methods

Participants & Setting

Students (n=109) from a French university (Mage= 20.24; SDage = 2; women = 75 %) were recruited through advertising on campus for a 30 minutes group experiment in exchange for £10. Our only a priori selection criterion was to exclude participant with fluent knowledge of Chinese or Japanese in order not to bias results from the indirect measures.

Procedure & Trial Design

Participants went through group sessions in a room with 12 computers. Each participant was separated from each other by wooden partitions and wore insulating headphones.

Participants were initially greeted by the experimenter and then randomly assigned to a 2 (depletion: yes vs no) x 3 (brand: "Heineken" vs "Steinlager" vs "Castrol Edge") factorial design. After performing the self-control (i.e., depletion) stage, participants were randomly assigned to one of the three experimental groups containing the sponsors branding for "Heineken", the "Steinlager" or "Castrol Edge" in order to manipulate the spillover effect.

Participants were then asked to complete indirect (implicit) and direct (explicit) measures of attitudes towards alcohol and the brands to which they were exposed. Participants then filled the Sport Spectator Identification Scale (i.e., reported level of felt closeness to the team; 21), the Involvement in the Message Scale (i.e., reported degree to which the participant consciously treated the messages, 22), and a Transportation in the Event Scale (i.e., reported cognitive and emotional involvement toward the event, 23). Participants finally filled the Perceived Awareness of Research Hypothesis, during which they were debriefed (PARH; 24). Both the experimenter and participant were blind to the conditions. All randomizations were done by the Inquisit 4 algorithm for randomization.

Material

Video excerpts. Each participant was exposed to 10 minutes of high definition video footage of a rugby match reflecting their assigned sponsorship condition. Within each sponsorship condition, participants were randomly assigned one of 3 possible excerpts of the same match to watch. The « eHei » condition comprised an excerpt of the final contest of the Heineken Cup between Leinster and Northampton containing numerous occurrences of sponsorship for the Heineken brand (e.g., banners, logo displayed on players, referee uniform and on the field). We edited the video so that the Heineken brand was always clearly visible onscreen during the 10-minute excerpt. The excerpts in the « eStei » condition were taken from the match between New-Zealand and England of the Steinlager series in 2014. In the no alcohol-sponsorship condition, excerpts from another rugby contest (semi-finals of the 2013 rugby championship between Australia and South Africa) were used containing sponsorship for a brand not related to alcohol (Castrol Edge).

Ego-depletion task. We used an attentional control task as an ego-depletion induction (total length = 7 minutes) in which participants had to pay attention to a video showing a woman being interviewed. Half of the participants were instructed to ignore distractor words appearing in the bottom right of the screen and therefore to regulate their attention (i.e., depletion group) while the other half did not receive any instruction regarding the distractors (i.e., control group).

Affect Misattribution Procedure (standard). Attitudes can be measured by direct -or explicit -attitudinal measures, which involves directly asking the participant to provide an evaluation of the attitudinal object. Researchers can also assess attitudes and other constructs using indirect or implicit measures whereby a person's attitudes or preferences, sometimes unconscious, towards a target or object is assessed by tapping into subtler and/or automatic/uncontrolled processes using timed reaction tasks and tasks such as the implicit association task. We used the Affect Misattribution Procedure (hence, AMPs) as an indirect measure of attitudes toward the sponsored brands and alcohol [START_REF] Payne | Automatic attitudes and alcohol: Does implicit liking predict drinking?[END_REF]. Participants were warned that a picture would appear briefly on the screen and that it would be immediately replaced by a Chinese pictogram, which would disappear quickly (both staying onscreen for 100ms, with a 75ms interval between the two stimuli). Once the Chinese pictogram disappeared, it was replaced by a mask (i.e., noise) until the participant gave his answer.

The participant was instructed to ignore the first picture and evaluate whether the Chinese pictogram seemed more or less pleasant than the average Chinese pictogram, on a scale from 1 (very unpleasant) to 4 (very pleasant). The pictogram being a neutral, unvalenced stimulus, the evaluation elicited by the picture has been shown to be misattributed to the pictogram [START_REF] Payne | Automatic attitudes and alcohol: Does implicit liking predict drinking?[END_REF]. Hence, the participant's attitude towards the image is evaluated indirectly from his response to the pictogram.

The task comprised 106 trials, in which the pictures were 20 generic and unbranded alcohol and water bottle pictures (10 of each category), 20 filler pictures (depicting food and furnitures), 12 branded alcohol pictures [START_REF] Pronk | Validation of the Amsterdam Beverage Picture Set: a Controlled Picture Set for Cognitive Bias Measurement and Modification Paradigms[END_REF], comprising a picture of an "Heineken" bottle and a "Steinlager" bottle and a neutral grey square as a neutral stimulus.

Affect Misattribution Procedure (modified).

A modified version of the AMP was used as a direct measure of attitude, to avoid variations in answers that could be attributed to variations in structural features of the tasks (e.g., nature of the stimuli, proposition vs pictures, Likert scales vs reaction times; for a more detailed discussion, see 27). In the modified AMP, the structure of the task remained the same, except that participants have to evaluate the picture and not the pictogram. The evaluation of the picture is done directly by the participant, rather than inferred via his evaluation of the Chinese pictogram.

Sport Spectator Identification Scale (SSIS)

. We used the 8-item Sport Spectator Identification Scale to assess participant's degree of identification toward the athletes and the sports team (18; see Appendix A2).

Involvement in the Message Scale (IMS).

We used a five-item scale assessing conscious and effortful processing messages presented during the match (19; See Appendix A1) Transportation in the Event Scale. Transportation has been originally defined as a one's emotional and cognitive involvement in a fictional narrative (e.g., emotional engagement).

Feeling transported in a narrative makes judgments toward the characters and the fiction in general more positive [START_REF] Green | The role of transportation in the persuasiveness of public narratives[END_REF]. Here, we checked whether the branding stimuli (i.e., banners in stadiums, logos displayed on athletes etc.) would be associated with the evaluative response elicited by the event and moderate the effect of incidental exposure to sponsor's branding/advertising. We used a modified 7 item Transportation Scale for sport events in order to evaluate participants' degree of emotional involvement toward the event (see Appendix A3).

Results

Reliability of Self-Report Scales. Self-reported measures had a good reliability overall (Transportation in the Event Scale, α = .80; Involvement in the Message Scale, α = .71 (Item 5 was removed from the scale, with item 5: α =.19); Sport Spectator Identification Scale, α = .84). We did not find any significant difference on these variables across the « eHei », « eStei » et « eNA » groups (see table 1a), nor any differences between gender in overall involvement in sport (see Table 1b and1c). We found a significant, medium-sized positive correlation between the Transportation and SSIS, r = 0.43, p < .001.

Main Analysis

A 2 (ego depletion: depleted vs control) x 3 (brand exposure) ANCOVA with Transportation, Involvement in the Message and Sport Spectator Identifications scales entered has covariates and with all interactions was conducted to assess effects on indirect (Model 1) and direct measures (Model 2).

Model 1: Effect of exposure to the « Heineken » brand on indirect measures of attitudes

toward « Heineken ». We found a nonsignificant main effect of exposure to the « Heineken » brand compared to other brands, showing more positive attitude scores on indirect measures, F(1, 70) = 3.50, p = .065, η2 = .047. We also found a nonsignificant moderating effect of depletion on exposure, F(1, 70) = 2.76, p = .10, η2 = .03, as well as an interaction trending toward significance between exposure and IMS scores, suggesting that the less participants engaged in conscious processing of the effect, the more positive the indirect measure scores were, F(1, 70) = 3.19, p = .07, η2 = .019 (see table 2 for descriptive statistics (three participants not included of their high Cook values (2.63 and 0.47, next being 0.08) and Deleted Studentized Residual (4.41)).

Effect of exposure to the « Heineken » brand on indirect measures of attitudes toward

Alcohol. Alcohol-related scores were computed by averaging scores on all alcohol stimuli that were unrelated to the exposed brands. Our hypothesis being that exposure to a prototypical brand would have a greater impact on attitudes toward alcohol than a nonprototypical brand, we tested a linear contrast opposing participants who were exposed to a prototypical brand (i.e., "Heineken") vs. a non-prototypical brand (i.e., "Steinlager") vs. no alcohol advertising. We found a significant linear trend showing that being in the « eHei » group compared to the « eStei » and « eNa » groups led to more positive scores on indirect measures toward alcohol, F(2, 57) = 5.87, p = .004, η2 = .059. No significant effect was found for the quadratic term (p =. 34). Contrast analysis revealed that the increase from "eHei" to "eStei" (Mdiff = 4.46) was not statistically significant (p = .45), but the increase from "eHei" to "eNa" (Mdiff = 14.49, p = .005) was significant, and nor did the change from "eStei" to "eNa" (Mdiff = 10.02, p = .01, see Figure 1). Planned contrast analysis comparing the « eHei » and « eStei » groups to the « eNA » group shows that mere exposure to alcohol sponsorship has a significant effect on indirect measures of attitudes toward alcohol, F(1, 73) = 4.65, p = .034, η2 = .038. We did not find any moderating effect of depletion, F(1, 73) = 0.01, p = .91, η2 < .001, but, again, a significant moderating effect of conscious processing of the message, F(1, 73) = 5.20, p = .02, η2 = .04, indicating that weaker conscious involvement in processing the messages lead to more positive indirect measures of attitudes toward alcohol for the « eHei » group compared to the « eStei » and « eNA » groups.

Model 2: Effect of exposure to the « Heineken » brand on direct measure of attitudes toward « Heineken » and Alcohol. There was no significant change on direct measures of attitudes toward « Heineken » in the « eHei » group compared to the pooled scores of the two other groups as well as no moderating effect of depletion (p>.63), (see table 3 for descriptive statistics) and no significant change in direct measures toward alcohol in the « eHei » group compared to the pooled scores of the two other groups and no moderating effect of depletion (ps>.66), that is no effect of the exposure to the "Heineken" brand on direct measures toward alcohol in general.. Hypothesis Awareness. Introducing PARH scores as covariates did not change significantly our estimates as well as removing participants above 3 standard deviations on the PARH scores [START_REF] Dang | The ego could be depleted, providing initial exertion is depleting: A pre-registered experiment of ego depletion[END_REF].

Conclusion & General Discussion

As predicted, we found that exposing participants to the "Heineken" brand led to more positive attitudes, as measured by indirect measures, toward the brand "Heineken" immediately after the watching the video. This is consistent with previous work in this area [START_REF] Zerhouni | Dynamic exposure to alcohol advertising in a sports context influences implicit attitudes[END_REF]. Similarly, we found that exposing participants to an alcohol brand, and more strongly to a prototypical alcohol brand, leads to more positive attitudes toward alcohol more generally.

Crucially, we found no moderating effect of ego-depletion. This suggest that at least in the context of sponsorship; attitude change can occur without deliberate involvement in processing the ads. Moreover, the less one reported being motivated to engage in conscious and deliberate processing of the advertising messages onscreen, the more positive the attitudes on indirect measures toward the "Heineken" brand and alcohol were. This is also confirmed by the consistent effect of alcohol brand/advertising exposure on indirect measures compared to direct measures, with indirect measures being more suited to capture automatic evaluative responses, while direct measures are more sensitive to deliberate and consciously formed responses [START_REF] Gawronski | Implicit and Explicit Evaluation: A Brief Review of the Associative -Propositional Evaluation Model[END_REF]. Our results suggest that sponsorship exposure may change attitudes in an automatic fashion, at least in the sense that is does not require the participant to have cognitive resources available to engage in volitional processing of the advertising stimuli. Eventually, we found evidence for the spillover (i.e., generalisation) effect of attitude change only when the sponsored brand was prototypical of the alcohol category, but not when the alcohol brand was relatively unknown of the participant or was unrelated to alcohol.

Implication for alcohol consumption & concluding remarks

Because implicit associations with alcohol are one of the most reliable predictors of alcohol consumption, and have a better predictive value than self-reported measures, especially among individuals with low cognitive resources [START_REF] Stacy | Implicit cognition and addiction : a tool for explaining paradoxical behavior[END_REF] and due to the massive exposure of sport-related content on TV in the daily lives of millions of individuals on the globe, one could assume that repeated exposure to alcohol sponsorship should have long-term effects on actual drinking behaviors, even on individuals who are passively exposed to advertising stimuli, thus making the question of how to resist those influences more complex.

Unfortunately, we were unable to collect data on participants' consumption after the experiment. Beyond the ethical problems (i.e., a potential rise in immediate alcohol consumption), we may not have found any substantial changes on actual consumption, given the subtle nature of the processes involved in such a short exposure time. However, cohort studies have already made it possible to establish the link between exposure to media content (i.e., films, TV show or advertisements) containing alcohol on drinking behavior, particularly among children and adolescents [START_REF] Dal Cin | Watching and drinking: expectancies, prototypes, and friends' alcohol use mediate the effect of exposure to alcohol use in movies on adolescent drinking[END_REF][START_REF] Koordeman | Exposure to alcohol commercials in movie theaters affects actual alcohol consumption in young adult high weekly drinkers: an experimental study[END_REF]. These studies were mainly correlational, and rarely differentiated between the different forms of exposure to advertising (e.g., incidental vs explicit), although some quasi-experimental studies have focused on studying the impact of explicit advertisements on alcohol consumption [START_REF] Sweldens | Evaluative Conditioning Procedures and the Resilience of Conditioned Brand Attitudes[END_REF]. However, our results still need to be replicated in order to estimate the magnitude of our effects on actual consumption.

A limitation of our study is that we did not evaluate the impact of exposure to sponsorship on maintaining long-term implicit attitudes. Some studies [START_REF] Wiers | Cognitive Bias Modification and Cognitive Control Training in Addiction and Related Psychopathology: Mechanisms, Clinical Perspectives, and Ways Forward[END_REF] have shown that attitudes acquired so via implicit processes are more resistant to change and are more stable over time. Hence, more concerning to us is the global impact on Public Health. Dual processes models of addictive behaviors predict that indirect measures of attitudes are better predictors of drinking for individuals that bear low executive functions [START_REF] Friese | The Association Between Implicit Alcohol Attitudes and Drinking Behavior is Moderated by Baseline Activation in the Lateral Prefrontal Cortex[END_REF]. Determining the duration of the effect of exposure to brand sponsorship on attitudes over time would provide Overall, this makes the question of how to resist those influences all the more central. For example, if sponsorship influence occurs through misattributing the affect elicited by retrieval to the product [START_REF] Fang | An examination of different explanations for the mere exposure effect[END_REF], simple strategies such as focusing, or even assessing the presence of the brands and logos could help reduce the impact of sponsorship on implicit attitudes. Identifying the processes by which implicit attitudes are formed could also help to inform policy decisions.

Figure 1 .

 1 Figure 1. Indirect measures toward the Heineken brand depending on type of sponsorship exposure and depletion

Acknowledgements

The authors would like to thank all members from the LIPPC2S at University Grenoble-Alpes who made interesting remarks and suggestions while designing and conducting the studies.

Funding

Funding for this study was provided by the Academic Research Community (ARC) 1 of the Région Rhones-Alpes in France and the French Ministry of Health (MILDECA). Nor ARC 1 neither the MILDECA had played any role in the study design, collection, analysis or interpretation of the data, writing the manuscript, or the decision to submit the paper for publication.

Availability of data and material

All raw data and material (i.e. videos, Inquisit scripts and stimuli) could be obtained by contacting the corresponding author (Oulmann Zerhouni).

additional proof as to the implicit nature of the formation of attitudes. More specific studies on this aspect are necessary and should be conducted in the future.

Our results converge with observational studies: there is indeed a positive and causal link between exposure to alcohol sponsorship and alcohol-related attitudes, which doesn't necessarily incur cognitive resources. What we showed is that alcohol sponsorship not only sends a message directly encouraging people to drink but tends to implicitly associate a product with a specific context and milieu (i.e., casual and desirable, etc.) in which alcohol is consumed. Such sponsorship campaigns are not conducted in vain. According to a study on the impact of advertising budgets on downstream alcohol consumption proposing a mathematical model of consumption data and advertising from the industry, Woodside [START_REF] Woodside | Advertising and Consumption of Alcoholic Beverages[END_REF] showed that, in a 20 years period, a 1% increase in investment in advertising messages promoting distilled alcohol increased the amount of alcohol consumed by 0.15% in the general population. Similarly, a 1% increase in spending on advertising for beer brands increased the total alcohol consumed by 0.25%. From another perspective, these data also provide insight into the potential effectiveness of prevention campaigns based on message display.

If sponsorship of alcohol-related messages does impact people's preferences automaticallyand unintentionally-then this reasoning can also be applied to prevention messages. However, this does not tell us how more complex characteristics of the advertising stimulus are treated (e.g., verbal content, explicit information such as slogan, compared to mere perceptual elements). One possibility would be to test how sponsorship elements containing elements relating to alcohol brands and verbal elements aimed at prevention interact to change alcohol-related attitudes and behaviors (e.g., Carlsberg banner with the message "drink responsibly").

Abbreviations

Declaration

Competing Interests

We have read and understood BMC Public Health policy on declaration of interests and declare that we have no competing interests.

Ethics approval and consent to participate

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. We cannot provide a name of the ethical committee that approved this study since no ethical committee existed at University Grenoble-Alpes when the studies were conducted.

Informed consent was obtained from all participants and none chose to withdraw from the procedure.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Consent for publication

Not applicable

Authors' contributions

All authors made substantial contribution to the paper. OZ designed and conducted the two studies in collaboration with LB and conducted all data analysis. KB greatly helped in drafting the paper and made substantial theoretical contributions to the paper. All authors read and approved the final manuscript.


A Desoutter
email: alban.desoutter@umontpellier.fr

I Panayotov
email: ivan.panayotov@umontpellier.fr

F Cuisinier
email: frederic.cuisinier@umontpellier.fr

D Carayon

Human tooth enamel tuft drapes revealed by microtomography

Keywords:

Objective: The tufts of human dental enamel are structures located at the enamel-dentin junction and whose origin has not been clearly established. Although studies have highlighted their protein content and hypomineralization, none has been able to shed light on their 3D structure. The aim of this study was to reveal the whole structure using high-resolution conventional microtomography. Design: Ten adult mandibular first and second molars and two primary mandibular first molars were sectioned and scanned with microcomputed tomography with a resolution between 4.7 and 5 micrometers. By determining the threshold discriminating dentin and tufts, we were able to reconstruct 3D meshes. Results: We revealed the exact pattern of the tufts in adult molars and discovered their distribution, their dynamics, and the existence of a regular undulation, forming a particular angle of approximately 30 degrees with the dentin surface. A spatial frequency of approximately 160 micrometers would be compatible with the variation in the orientation of groups of dental enamel rods. In contrast, the present setting is not sufficient to extract similar information for primary teeth. Conclusions: Enamel tufts have a specific pattern, with an oriented draped form and are regularly spaced. The possible connection between these undulations and the Hunter-Schreger bands (diazonias and parazonias) needs to be studied.

Introduction

Dental enamel is the "hardest" tissue of the human body, with a Young's modulus between 70 and 100 GPa, depending on the type (incisor, molar, canine…), age and teeth (Habelitz et al., 2001a;[START_REF] Xu | Indentation damage and mechanical properties of human enamel and dentin[END_REF][START_REF] Zheng | Spatial distribution of the human enamel fracture toughness with aging[END_REF]. The enamel structure consists primarily of calcium hydroxyapatite (96 wt%), protein (2 wt%) and water. Under the enamel layer, dentin is a mineralized connective structure comprised of 45% hydroxyapatite, 33% organic material and 22% water. The dentin organic phase is primarily type I collagen (90%), with a low percentage of type III, V, and fibronectin, and 10% water-rich noncollagenous proteins (proteoglycans and glycosaminoglycans) (Ten [START_REF] Cate | Ten Cate's oral histology: Development, structure, and function[END_REF]. At the interface of the enamel and dentin, four features have been described: tubular dentin, mantle dentin, and aprismatic and prismatic enamel. This transitional zone is called the dentin-enamel junction (DEJ). The enamel rods are not colinear and form angles between each other [START_REF] Beniash | The hidden structure of human enamel[END_REF]. The result of this structure is incredibly resilient during the tooth's life. Each day, thousands of times, teeth are subjected to forces during eating that can reach 1000 N, with a mean of approximately 700 N, depending on sex, age, weight, and pathology [START_REF] Braun | A study of bite force, part 1: Relationship to various physical characteristics[END_REF]. Enamel is very hard, but as a nonductile material, it is fragile. The fracture toughness of external and internal enamel were established in controlled crack growth experiments as 0.67 ±0.12 MPa⋅m 0.5 and 1.13-3.93 MPa⋅m 0.5 , respectively. Tufts are the primary fracture sources, but prism interweaving and self-healing could limit crack propagation [START_REF] Bajaj | On the R-curve behavior of human tooth enamel[END_REF].

The secondary structures of enamel in the vicinity of the DEJ are tufts, lamellae and spindles [START_REF] Palamara | The ultrastructure of spindles and tufts in human dental enamel[END_REF]. Tufts are linked to orientation changes in ameloblasts. The resulting divergence of enamel rods creates hypomineralized spaces starting in the DEJ. Tufts must not be confused with lamellae, which is a linear defect starting at DEJ and proceeding through the enamel to the surface [START_REF] Palamara | The ultrastructure of spindles and tufts in human dental enamel[END_REF]. The lamella, spindle and tuft are hypomineralized formations, with different ratios of phosphate and calcium [START_REF] Ogita | A histological study of the organic elements in the human enamel focusing on the extent of the odontoblast process[END_REF]. Tufts are classically described as hypomineralized ribbon-like structures (Fig. 1) starting at the DEJ and extending to a inner third of the thickness of the enamel. The 3D shape of the tuft has been analysed by optical microscopy by changing the focal plane every 6 μm. Tufts appeared as undulating, disorganized structures [START_REF] Osborn | The 3-dimensional morphology of the tufts in human enamel[END_REF]. These structures were also observed in bovine teeth [START_REF] Mehr | Histomorphometric evaluation of organic enamel elements in erupted bovine teeth. Part I. Enamel tufts[END_REF].

A combined scanning and transmission electron microscopy examination of etched human teeth defined tufts as having "a wavy course and appearing as bundles of tubular structures". [START_REF] Amizuka | Ultrastructural and immunocytochemical studies of enamel tufts in human permanent teeth[END_REF]. Enamel tufts exhibit a relatively simple ordering in rows away from the cusp. Since tufts lie between prisms, they indicate disorder in the patterning of ameloblast trajectories at the dentin surface. Strain-cued motility was proposed to explain the formation of dental enamel structures, mainly curved prisms. Dental enamel is formed during amelogenesis by a population of ameloblasts that move about laterally within an expanding curved sheet, subject to continuously evolving spatial and temporal gradients in the strain [START_REF] Cox | Cells as strain-cued automata[END_REF]. Such theories give little explanation of the tufts' presence on the surface of the dentin. One of their functions could be to limit the strain between or inside ameloblast groups. Tufts at the interface of dentin and enamel, containing organic matter, could stabilize the tooth against the propagation of a break by self-healing [START_REF] Myoung | Morphology and fracture of enamel[END_REF]. The tufts would therefore play the role of preventing cracks but initiate them when there is too much stress at one point. Confocal Raman microscopy revealed that the tuft width ranges from 5 to 15 μm, and the height can reach 150/200 µm: the phosphate peak intensity (PO 4 3-) decreases between 6 and 8 times [START_REF] Desoutter | Confocal Raman data analysis of tufts and spindles at the human dentinenamel junction[END_REF].

As the 3D organization of tufts remains elusive with no direct 3D observation since the primary paper of Amizuka et al. [START_REF] Amizuka | Ultrastructural and immunocytochemical studies of enamel tufts in human permanent teeth[END_REF], we aimed to use high-resolution µCT with a large field of view. An entire tooth, or a large portion of it, can be scanned with 4.5 to 5 micrometer resolution superior to the tuft width ranging from 5 to 10 μm.

Materials and methods

Sample preparation

Ten human first and second mandibular molar teeth (5 each), extracted for orthodontic reasons with patient consent -process No. 2014-2198 -local ethical research committee "Montpellier Sud-Méditerranée IV", were collected and stored in distilled water. All donors were Europeans between 25 and 40 years old; 6 teeth were from men and 4 from women. Each tooth was sectioned to create a 3x3x3 mm 3 specimen, including the cusp, enamel and dentin. The cube-shaped samples were preserved in distilled water. To compare with the results obtained with adult teeth, two deciduous molars were also prepared.

Microtomography

Each sample was placed in an EasyTom 150 kV microcomputed tomography with an Xact software interface (RX Solution, Chavanod, France). A 1 mm aluminum filter was placed in front of the X-ray source.

The voltage used was 71 kV, with an intensity of 66 μA and a tube power of 4.68 W. To increase the signal-to-noise ratio (SNR), 4 images were recorded and averaged, and the gain reached 7, with an angular step of 0.25 degrees. A total of 1440 radiography-type images were collected over approximately 30 minutes, and the reconstruction algorithm was performed by Xact software. A total of 1808 16-bit Tiff images were reconstructed in gray shades image, with a voxel size in the range of 4.7 to 5 micrometers. Ring artefacts and beam hardening corrections were not used.

Calculation of density

The reconstructed greyscale intensity of each image voxel does not relate directly to mineral density alone. We assume that the X-ray attenuation within enamel is dominated by and can be approximated as the X-ray attenuation of the mineral compound hydroxyapatite (HA), which has the formula Ca 5 (PO 4 ) 3 (OH). Assuming a density of 2.72 g/ cm 3 for enamel and 1.97 g/cm 3 for dentin (Gradl et al., 2016), we evaluated the variation in density in the tuft with a linear relationship between those two values and their gray shade.

Surface reconstruction

Tuft intensity profiles were performed with FIJI (v1.53c, National Institutes of Health, USA) and exported in Excel to be plotted. This allowed measurement of the width of the tufts.

To visualize the tuft structure in 3D, gray shade images were imported into FIJI and transformed into binary images to select the voxels of interest.

To select the pixels of interest, the gray level values and standard deviations of the dentin, enamel and tuft centers were retrieved. For dentin, the mean value minus two standard deviation values was taken. To select the pixels of the tufts, an empirical method was used: the upper threshold was taken as the mean value minus three standard deviations.

Gaussian low-pass filtering smoothing was applied with sigma (standard deviation) equal to 1. The surface was visualized in FIJI (3D viewer) and exported as an STL file. Resampling and cropping of the ROI was performed in MeshLab (v2020.12, Consiglio Nazionale delle Ricerche, Italy).

Results

Tufts appear as clear ribbon-like structures perpendicular to the DEJ and expand in the enamel (Fig. 1). In all figures presented in this article, the x-y plane is tangential to the DEJ, the x-axis is perpendicular to it, and the z-axis is colinear to the longitudinal tooth axis (see Fig. 1C).

For each sample scanned by µCT, 1808 gray shade images were obtained, and approximately 1600 image stacks were finally selected after cropping. On each sample, we can distinguish a series of white pixels forming a wave-shaped structure starting at DEJ and penetrating the enamel to a 200 μm depth (Fig. 2A,C). When observed along the x-axis, the tufts appear as continuous wavy hypomineralized lines. The tuft lines are collinear (Fig. 2B).

Reconstructed 3D meshes allow visualization of the tuft lines. They confirm that the longitudinal axis of the lines and their wavy shape surface extracted after thresholding permits visualization of the distribution of the tufts and orientation of the wave pattern. See Fig. 3. The surface of interest, where the tufts are clearly visible with a pattern, extends to a length of 2.5 mm.

Microtomography images and 3D meshes allow accurately measurement of the morphology of the tufts.

All measures obtained from 40 tuft drapes are presented in Table 1. In this table, the maximum height is the maximum distance between the DEJ and the top of the tuft. The tuft drapes length is from the cusp to the apical ends. The tuft width is measured in several zones of the tuft. The space between the tufts represents the distance between two tufts draped along the y-axis; the drape spatial periodicity is measured as the distance between two undulation ridges; the α angle, as shown in Fig. 4A, is the angle between the drape ridge and the DEJ; and finally the tuft gray value converted to grams/cm^3 of HA.

The results obtained for primary teeth did not allow us to clearly highlight the 3D structure of the tufts.

Discussion

To our knowledge, the 3D structure of tufts has never been described. Tufts are almost always described as 2-dimensional structures, classified as enamel secondary structures, ranging from the DEJ to the first third of the enamel thickness. The micro-CT revealed that the 2D structures correspond to 3D drapes extending longitudinally from the cusp area in the direction of the tooth collar, spreading over 2.5 mm. Amizuka et al. in 1992 described tuft and tuft plates that could be related to tuft drapes. On scanning electron microscopy images of dentin surface, after the enamel has been removed by etching, tufts cover the perimeter of the premolar very homogeneously. This divergence in results could be explained by the teeth type or by the population studied. Comparatively, we provided actual 3D images of tufts drapes, and we also determined the degree of mineralization of these structures, without having to remove the enamel, in a totally nondestructive way. The structure of these tufts clearly indicates a particular pattern found in all the samples: an undulation, with a clearly marked periodicity. See Fig. 4 in particular.

The enamel prisms have a diameter of approximately 5 μm [START_REF] Habelitz | Mechanical properties of human dental enamel on the nanometre scale[END_REF], so the undulation observed cannot be the result of a variation in the orientation of single prisms. It is more likely that these hypomineralized structures are the result of a variation in the orientation of ameloblast clusters during the hydroxyapatite mineralization phase. The characteristic distance between two tufts is 188 μm (SD 71), and the average of the spatial periods observed for the tuft corrugations is 163 μm (SD 34). Hunter-Schreger bands have spatial periods that range from 83 to 250 μm for permanent molars enamel [START_REF] Lynch | Hunter-Schreger band patterns in human tooth enamel[END_REF]. The range of such values is concordant with the periodicity observed. It is therefore possible that the undulation of the tufts can be correlated with the formation of Hunter-Schreger bands. However, angulation of such bands and DEJ in molars is approximately 35/40 degrees, more than the angulation of the tuft wave pattern reported in Table 1. The angulation of the tufts drapes undulation could be related to the orientation of the trajectory of the ameloblast populations relative to the growth front [START_REF] Cox | Cells as strain-cued automata[END_REF].

Amelogenesis starts at the dentine surface at the cuspal tip of the mesenchymal papilla. The strain-cued model of ameloblast migration is based on a homogeneous and continuous layer of cells perpendicular to the growth front [START_REF] Cox | Cells as strain-cued automata[END_REF]. The layer of ameloblasts is relatively rigid, as the cell bodies are elongated, and two junctional complexes associated with terminal webs are present at both extremities. If the curvature of the growth front exceeds the elasticity of the ameloblast layer, a local defect could appear. These defects, as grain boundaries in the material, could migrate and form dislocations. Dislocation locally accumulates in the constraint, and this is possibly the role of the tufts drapes.

Regarding the content of the structure itself, the results here must be interpreted with great caution. Indeed, the tufts are hypomineralized,

Table 1

Tufts drapes morphological parameters. Angulation α: angle between the dentin and orientation of the wave-shaped pattern (see Fig. 4); n (tufts): 40. and the values found in this study are 2.15 g/cm 3 , i.e., a density between dentin and enamel. Due to the characteristic size of a tuft, we could not draw conclusions about the content of the tuft, i.e., whether it is a weakly mineralized structure, containing more organic matter, or whether it is a space totally devoid of any mineral phase. This question highlights a limitation of the present study: the resolution reveals the 3D structure of the enamel tufts but does not allow us to know its interior architecture. Additionally, it is possible that existing structures smaller than the resolution or of the same size were missed. A future study combining a resolution close to or below a micrometer and a large field of view will be required to examine the whole sample.

Concerning the primary teeth, 3D structures are also visible. Moreover, the undulation with spatial periodicity seems to be similar to that of adult teeth. However, the width and/or the degree of mineralization make the SNR very weak and does not permit visualization of the whole region of interest with tufts. See Supplementary Fig. 2. This did not allow for studying the 3D structure. Finally, some lines of draped tufts are visible, but only for a few hundred micrometers. With our settings, conventional microtomography, even with a high resolution, does not permit the study of tufts in primary teeth to extract morphological parameters.

Conclusion

Microtomography, with its voxel size below 5 μm and a field of view in the order of approximately 20 millimeters, makes it possible to reconstruct the 3D secondary structures of the enamel. We thus noticed that the tufts of the enamel, in permanent molars, form wavy drapes starting from the cusp in the direction of the collar, of a total length that can exceed a millimeter, and of a height that can reach more than 200 micrometers. The drapes have a periodic undulation of approximately 160 micrometers, forming an inclination with the surface of the dentin of approximately thirty degrees. This hypomineralized structure could therefore be related to a variation in the orientation of the enamel prism groups. These elements make it possible to consider a comparison with the enamel dentin junction in different human populations and to verify their presence within the animal kingdom. Finally, more powerful tools, such as a synchrotron X-ray source, with increased resolution and still a wide field of view, would be able to give further details about the architecture of the secondary structures of the DEJ. This is also necessary to improve the image quality, in particular the SNR, and extract information from primary teeth.

CRediT authorship contribution statement

A. Desoutter: contributed to conception and design, data acquisition, analysis, and interpretation, drafted and critically revised manuscript. I. Panayotov: contributed to analysis, drafted manuscript and critically revised manuscript. F. Cuisinier: contributed to conception and design, data interpretation, drafted manuscript, critically revised manuscript. D. Carayon: contributed to conception and design, data interpretation, drafted manuscript, critically revised manuscript.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Fig. 1 .

 1 Fig. 1. A-B) Optical microscopy image of a first mandibular molar tooth at the enamel dentin junction area. D: dentin, E: enamel; DEJ: dentin enamel junction; black arrows: tufts. C) Molar surface and geometrical axis used in the present study.

Fig. 2 .

 2 Fig. 2. Permanent molar A) microtomography gray shade image in a plane perpendicular to the DEJ. Arrows: tufts B) microtomography gray shade image view along the x-axis perpendicular to the DEJ, i.e., perpendicular to picture A; tufts appear as wavy black lines (indicated by arrows); C) microtomography image of tufts after data treatments by interpolation and Laplacian smoothing; same orientation as image A.

Fig. 3 .

 3 Fig. 3. 3D mesh reconstruction of a large field of view of DEJ with tuft.

Fig. 4 .

 4 Fig. 4. A, B, C) Three different views of a tuft line. A: α: angle between the dentin surface (y,z plane) and the ridge of the wave-shaped tufts (black line). A and B are figures extracted from mesh seen in Fig. 3; Red line: spatial periodicity of waves. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Acknowledgments

Authors thank Renaud Lebrun for his assistance in data acquisition. 3D data acquisitions were performed using the µ-CT facilities of the MRI platform member of the national infrastructure France-BioImaging supported by the French National Research Agency (ANR-10-INBS-04, «Investments for the future»), and of the Labex CEMEB (ANR-10-LABX-0004) and NUMEV (ANR-10-LABX-0020).

The authors would like to thank Paul Tafforeau, Beamline scientist in Structure of Material group at Synchrotron (Grenoble) and specialist of tooth enamel, for his comment on images and discussion about enamel tufts.

This research was not funded by any state or institutional agency.

Appendix A. Supplementary material

Supplementary data associated with this article can be found in the online version at doi:10.1016/j.archoralbio.2022.105487.


Aurélie Antunes

Philippe Robin

Gilles Mourier

Michel De Waard

Rémy Béroud

Denis Servent

Evelyne Benoit

Rémy Beroud

Evaluation of crotalphine effects, a rattlesnake potent analgesic toxin, on the tetrodotoxin-sensitive Na current of adult mouse dorsal root ganglion neurons

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Evaluation of crotalphine effects, a rattlesnake potent analgesic toxin, on the tetrodotoxin-sensitive Na current of adult mouse dorsal root ganglion neurons

INTRODUCTION.

Crotalphine is an analgesic peptide identified in the venom of the South American rattlesnake Crotalus durissus terrificus.

Although its antinociceptive effects are well documented, its direct mechanisms of action are still under investigation. The aim of the present work was to study the action of the crotalid peptide on the sodium channel subtype Na V 1.7, a genetically validated pain target. To this purpose, the effects of crotalphine were evaluated on the tetrodotoxin-sensitive Na current of dorsal root ganglion neurons of adult mice, using the whole-cell patch-clamp configuration, and on the cell viability, using the propidium iodide fluorescence and trypan blue assays.

CONCLUSION.

Taken together, these results point out, for the first time, the effectiveness of crotalphine to act on the Na V 1.7 channel subtype, directly and/or indirectly by affecting cell membrane integrity. This mechanism of action could contribute to the peptide analgesic properties.

Acknowledgments. The authors are grateful to Amaury Herbet (SPI, CEA de Saclay, Gif-sur-Yvette, France) for kindly providing human skin melanoma (UACC-257) cells.

Linear relationship (r 2 = 0.988) between the peak Na current blockade and the leakage current amplitude in the absence and in the presence of 5, 10 and 50 μM of toxin. Means ± S.E.M. of data obtained from 4-9 neurons. *: P ≤ 0.049.

Control Crotalphine

Concentration-response curve of crotalphine steady-state effects on TTXsensitive Na current. Each value is expressed as percentage of that determined before toxin application.

Crotalphine induces decreased DRG neuron viability

  Current-voltage relationships (left panel), and steady-state inactivation-(open circles) and conductance-(filled circles) voltage relationships (right panel), before (black circles) and after (pink circles) exposure of neurons to 50 μM of crotalphine. Each value is expressed as percentage of either maximal peak amplitude of current at strongly negative pre-pulse voltages or maximal conductance calculated at strongly positive test-pulse voltages.Traces of TTX-sensitive Na currents recorded before (in black) and after (in pink) application of 50 μM of crotalphine. On the right, the toxin peak current is normalized to that of control.1. A crotalphine concentration of 18.70 μM is necessaryto inhibit 50% of Na current4. Crotalphine induces increased leakage current amplitudeA decrease of DRG neuron, but not of CHO cell, viability is detected in the presence of crotalphine (50 μM), using the propidium iodide fluorescence assay (a,b,c). Similarly, a decrease of DRG neuron and UACC-257 cell viability is detected in the presence of crotalphine (50 μM), using the trypan blue assay (d). Note that the toxin induces a maximal decrease of 28% of cell viability.Means± S.E.M. of data obtained from 3-12 cell cultures. *: P ≤ 0.0500, **: P ≤ 0.0050 and ***: P ≤ 0.0005 (b,c,d). Kinetic parameters of activation (TimeA and SlopeA) and inactivation (TimeI and SlopeI) of 1 TTX-sensitive Na current recorded from DRG neurons under control conditions and in the 2 presence of 50 µM of crotalphine (means ± S.E.M. of 4 neurons). Kinetic parameters of activation (Time A and Slope A ) and inactivation (Time I and Slope I ) of TTX-sensitive Na current recorded under control conditions and in the presence of 50 μM of crotalphine (means ± S.E.M. of 4 neurons).

  Representative experiment of the time courses of crotalphine (50 μM) effects on the leakage (light circles) and peak Na (dark circles) current amplitudes, before and after toxin addition (arrow). Note the crotalphine-induced increase in leakage current amplitude of approximately 150%. acid (non-standard amino acid)


Boris Brasseur
email: brasseur@mnhn.fr

François Sémah
email: semahf@mnhn.fr

Anne-Marie Sémah
email: semah@bondy.ird.fr.

Tony Djubiantono
email: tonydjubiantono@yahoo.com

Pedo-sedimentary dynamics of Sangiran dome hominid bearing

The thick sedimentary series of the Sangiran dome are known to reflect the geological evolution of Central Java since the beginning of the Quaternary until the Middle Pleistocene. Homo erectus fossils are found in the c. 1.5 M.a. Pucangan series up to the c.0.8 M.y. Kabuh layers.

This study combines field survey, micromorphological approach and use of palynological data. The characterisation of successive pedoclimatic contexts and toposequences help to reconstruct the local palaeogeography and inform about climates (mainly influenced by south-eastern Asia monsoon cycles) that predominated during periods of palaeosoil development.

The basis of Upper Pucangan series displays the earliest fully continental deposits, corresponding to the development of an open landscape that succeeds to wide coastal swamps and rain forest. Upper in the stratigraphy, environments depicting a contrasted seasonal climate with a long dry season alternate with periods of more humid palustrine conditions.

A further tectonic uplift of the hill ranges bordering the Solo depression (in which is located the Sangiran dome) resulted into severe erosion of the regional soil cover. Transported by ephemeral streams, series of pedorelics and pedological concretions accumulated in the topographic depressions.

Recurrent aridity proxies occur in the studied paleosoils found in the overlying Kabuh series (which yield the most numerous hominid fossils), reflecting a long dry season and an open vegetation landscape.

Key Words : Soil micromorphology, Stratigraphy, Homo erectus, Paleosols, Monsoon, Sedimentology. Pleistocene, Java, palynology


Bruno Mériaux

Arnaud Breloy

Chengfang Ren

Mohammed Nabil

El Korso

Philippe Forster

Modified Sparse Subspace Clustering for Radar Detection in Non-stationary Clutter

Keywords: Target detection, Non-stationary clutter, Subspace clustering

Detecting targets embedded in a noisy environment is an important topic in adaptive array processing. In the traditional statistical framework, this problem is addressed through a binary hypothesis test, which usually requires the estimation of side parameters from secondary data. The latter are assumed to be homogeneous and targetfree, which is in practice questionable. Indeed, secondary data are usually corrupted by radar clutters and/or jammers which can be non-stationary and locally low rank. Fortunately, the latter behaviors can be well acknowledged by a union-of-subspaces model. In this work, we propose a modified subspace clustering model which can be solved using convex optimization algorithms. In the context of multiple sparse target detection and localization, a comparison is performed with various robust detection methods exhibiting advantages and drawbacks of the proposed one.

I. INTRODUCTION

Detecting targets enclosed in a noisy environment is a major topic in adaptive array processing, which still drives research interest. Traditionally, this problem is addressed through the statistical framework by expressing a binary hypothesis test to discriminate the presence of targets or not [START_REF] Kelly | An adaptive detection algorithm[END_REF][START_REF] Kraut | Adaptive subspace detectors[END_REF]. The computation of decision statistics usually requires the estimation of side parameters, such as the interference plus noise covariance matrix. This step is crucial since it directly impacts the performance of the detection process. Thus, this topic has been widely investigated through various statistical models [START_REF] Conte | Adaptive detection schemes in compound-gaussian clutter[END_REF][START_REF] Gini | Covariance matrix estimation for CFAR detection in correlated heavy tailed clutter[END_REF][START_REF] Ollila | Complex elliptically symmetric distributions: Survey, new results and applications[END_REF][START_REF] De Maio | Modern radar detection theory[END_REF][START_REF] Woodbridge | Signal detection in complex structured para normal noise[END_REF].

However, in the classical statistical adaptive detection paradigm, the parameter learning step requires the availability of a sufficiently large dataset, called secondary data, which are assumed to be homogeneous and target-free. These conditions are not necessarily met in practice, depending on the observation environment, the measuring system, or the acquisition mode. As examples, the secondary dataset can be reduced in size, heterogeneous (i.e., non-stationary) or contaminated by targets. This issues motivated the development of numerous robust detection methods and have been addressed with various approaches, such as regularization or subspace methods [START_REF] De Maio | Modern radar detection theory[END_REF][START_REF] Zoubir | Robust statistics for signal processing[END_REF][START_REF] Goldstein | A multistage representation of the Wiener filter based on orthogonal projections[END_REF][START_REF] Honig | Adaptive reduced-rank interference suppression based on the multistage Wiener filter[END_REF][START_REF] Somasundaram | Reduced-dimension robust capon beamforming using Krylov-subspace techniques[END_REF].

Following [START_REF] Breloy | Robust subspace clustering for radar detection[END_REF], we propose in this paper to leverage robust subspace clustering techniques in order to alleviate a possible nonstationarity of the secondary dataset. This implies to reformulate the detection problem as a structured recovery/regression rather than a statistical hypothesis test (see e.g. [START_REF] Mardani | Recovery of low-rank plus compressed sparse matrices with application to unveiling traffic anomalies[END_REF]). Indeed, the whole dataset (primary and secondary data) can be modeled as the sum of sparse targets embedded locally in low rank clutter with -possibly nonstationary -interferences. In this context, recent machine learning techniques addressing the problem of subspace clustering and/or sparse matrix recovery can be used. For example, the Robust Principal

The work of B. Mériaux is partially funded by the Direction Générale de l'Armement (D.G.A). This work is also supported by the ANR ASTRID MARGARITA ANR-17-ASTR-0015.

Component Analysis [START_REF] Candès | Robust principal component analysis?[END_REF] is well-suited for the recovery of "lowrank + sparse" matrices. Here, the non-stationarity of radar clutters/jammers can be better acknowledged by a union-of-subspaces model, which naturally points to the use of the subspace clustering techniques [START_REF] Elhamifar | Sparse subspace clustering: Algorithm, theory, and applications[END_REF][START_REF] Bian | Bi-sparsity pursuit for robust subspace recovery[END_REF].

In this context, [START_REF] Breloy | Robust subspace clustering for radar detection[END_REF] proposed the use of Sparse Subspace Clustering (SSC) for radar detection and illustrated its feasibility on a real dataset. Following from this work:

• We explore a variant of SSC proposed in [START_REF] Elhamifar | Sparse subspace clustering: Algorithm, theory, and applications[END_REF] (formulating a relaxed convex problem) to include a dictionary, needed in radar detection.

• We illustrate the robustness of the SSC approach to non-stationary interference on simulated data. This paper is organized as follows. In section II, the data model is introduced. Some limitations of the classic statistical detection are emphasized, leading to a new approach presented in Section III. In this section, we reformulate the detection problem as the recovery of a sparse matrix. In section IV, we compare the different approaches for target detection in non-stationary jamming.

In what follows, the notation A 1 is for the 1-norm of the matrix A ∈ C n×m , which is given by A 1 = n,m |an,m|. The operator diag (A) collects all the diagonal elements of the matrix A into a vector. For a matrix A, Tr (A) denotes the trace of A.

II. PROBLEM SETUP

A. Data model

Let be a radar receiver, composed by M antenna elements, collecting K snapshots, z k ∈ C M , k = 1, . . . , K. Theses samples are a combination of different contributions, modeled as below [START_REF] Rangaswamy | Robust adaptive signal processing methods for heterogeneous radar clutter scenarios[END_REF]:

z k = v k + c k + n k k = 1, . . . , K
where,

• v k is related to the target responses. Due to physical considerations and the geometry of the receiver, the structure of the related steering vector d, is known. Then a dictionary D mapping the whole angleof-view can be constructed as D = [d1, . . . , dT ], with T the size of the dictionary. Thus, the vector v k can be expressed as

v k = Dα k (2)
where α k is the vector of power/phase shifts coefficients. In practice, only a small number of targets is active compared to the size of the dictionary. Therefore, α k is a sparse vector.

• c k refers to the interferences, such as ground clutter and/or jammers.

From physical consideration on the system [START_REF] Goodman | On clutter rank observed by arbitrary arrays[END_REF], we know that the clutter contribution belongs to a low-rank subspace of size R M . For a sufficient number of samples, i.e. K > R, we can then consider that a vector c k can be expressed as a linear combination of the other samples, cp, p ∈ [[1, K]] \ {k}:

C h [c1, . . . , cK ] = C h W h , such that W h i,i = 0 (3)
where W h sparse. The relation in ( 3) is also called the selfrepresentation property of the data [START_REF] Elhamifar | Sparse subspace clustering: Algorithm, theory, and applications[END_REF].

• n k denotes a dense noise, e.g., the thermal noise, which is assumed to be white centered Gaussian distributed: n k ∼ CN 0, σ 2 IM . By concatenating column-wise for all the samples, the model in ( 1) can be rewritten in a matrix form by

Z h = V h + C h + N h = DA h + C h + N h (4)
where the matrix A h = [α1, . . . , αK ] is sparse.

In the case where the whole received samples are not necessarily homogeneous, e.g., the low-rank subspace describing the interference changes during the acquisition process, the model (4) still holds. Indeed, we can consider that the heterogeneity in the samples can be modeled as an union of J unknown homogeneous subpartitions. For each homogeneous subpartition of Kj snapshots, such that J j=1 Kj = K, the model in (4) still remains valid. Then by concatenating column-wise each subpartition, we finally obtain

Z = V + C + N with V = DA C = CW, diag (W) = 0 ( 5
)
where W is a block diagonal (up to a sorting permutation) composed by the matrices W h 1 , . . . , W h J . We recall that the sparse matrix A, which is related to the present targets, is the center of interest in our detection application. However, it is worth mentioning that the sparse matrix W, which is block-diagonal up to a sorting permutation, is useful from a clustering perspective.

B. Limitations of the classic statistical detection

Traditionally in statistical signal processing, the target detection problem can be formalized by the following binary hypothesis test:

H0 : z0 = c0 + n0 ; z k = c k + n k , ∀ k ∈ [[1, K]] H1 : z0 = Dα0 + c0 + n0 ; z k = c k + n k , ∀ k ∈ [[1, K]]
where z0 is the primary sample, which is the tested sample and z k 's are the secondary data, which are assumed to be independant, identically distributed (i.i.d.), and target-free. Under H0, the received signal only contains the clutter response, i.e. interference and noise. Under H1, the tested signal additionally contains a target response. Several approaches have been proposed in the literature to design a detector [START_REF] Kelly | An adaptive detection algorithm[END_REF][START_REF] Kraut | Adaptive subspace detectors[END_REF][START_REF] Conte | Adaptive detection schemes in compound-gaussian clutter[END_REF][START_REF] Gini | Covariance matrix estimation for CFAR detection in correlated heavy tailed clutter[END_REF][START_REF] Ollila | Complex elliptically symmetric distributions: Survey, new results and applications[END_REF][START_REF] De Maio | Modern radar detection theory[END_REF][START_REF] Woodbridge | Signal detection in complex structured para normal noise[END_REF][START_REF] Zoubir | Robust statistics for signal processing[END_REF][START_REF] Rangaswamy | Robust adaptive signal processing methods for heterogeneous radar clutter scenarios[END_REF]. Among them, the most powerful tests are usually based on likelihood-ratio, namely the Neyman-Pearson test. In practice, the latter involve some unknown parameters of the chosen interference-plus-noise model such as the covariance matrix of the clutter. Therefore, a first step of estimation should be achieved, giving an adaptive nature to the obtained detector. To that end, the secondary data are used for the clutter's covariance estimation. The estimate plays a central role in the performance of the resulting detector, which is why this step is still driving scientific research [START_REF] Ollila | Complex elliptically symmetric distributions: Survey, new results and applications[END_REF][START_REF] Soloveychik | Tyler's covariance matrix estimator in elliptical models with convex structure[END_REF][START_REF] Sun | Robust estimation of structured covariance matrix for heavy-tailed elliptical distributions[END_REF][START_REF] Kammoun | Optimal design of the adaptive normalized matched filter detector using regularized Tyler estimators[END_REF].

However, this 2-step scheme is based on two important assumptions, which can be inaccurate in practice. The first one is about the homogeneity of the secondary data, i.e. these samples are assumed to be i.i.d.. This means that either the potential non-stationarity of the clutter is not taken into account or we know a priori the partition of the secondary data in which each cluster contains i.i.d. samples. The second hypothesis concerns the target-free nature of the secondary data, which can be invalidated in the case of the presence of several targets in the observation area. From these two mentioned limitations, we propose a novel approach of the problem in order to perform a simultaneous estimation/detection process without assuming the availability of such secondary data.

III. SPARSE SUBSPACE CLUSTERING

A. Robust Subspace Recovery via bi-sparsity

In order to perform a simultaneous estimation and detection from collected observations, which are a noisy version of DA + C, we aim to recover a sparse matrix, containing the information of the targets and an union of low-rank subspaces, corresponding to non-stationary interferences. This approach, while novel for radar detection, is under a lot of ongoing investigations in machine learning or computer vision problems [START_REF] Elhamifar | Sparse subspace clustering: Algorithm, theory, and applications[END_REF][START_REF] Bian | Bi-sparsity pursuit: A paradigm for robust subspace recovery[END_REF]. The following minimization problem min

W,A,C W 1 + λ A 1 s.t.      (i) Z = DA + C, (ii) C = CW, (iii) diag (W) = 0 (6)
initially introduced in [START_REF] Bian | Bi-sparsity pursuit for robust subspace recovery[END_REF] without dictionary, and then applied with a dictionary in [START_REF] Breloy | Robust subspace clustering for radar detection[END_REF], is relevant to solve this task. Indeed, the 1- norm promotes sparsity of the matrices W and A and the parameter λ balance the two terms in the objective function. Therefore, the recovered sparse matrix A allows us to build a detection map and then to compare with a threshold the non-zero elements in order to decide the presence of the targets or not and to localize the activated atoms in the dictionary D. Due to the bilinear constraint (ii), the problem ( 6) is non-convex. The optimization can be achieved by the linearized version of the Alternating Direction Method of Multipliers (ADMM) [START_REF] Boyd | Distributed optimization and statistical learning via the alternating direction method of multipliers[END_REF][START_REF] Lin | Linearized alternating direction method with adaptive penalty for low-rank representation[END_REF].

B. Relaxation of the initial problem

Based on a rewriting of the problem (6) introduced in [START_REF] Elhamifar | Sparse subspace clustering: Algorithm, theory, and applications[END_REF], we also propose to study a convexified modification of this problem. Indeed, starting from Z = DA + C + N and C = CW, we obtain

ZW = DAW + CW + NW = DAW + Z -DA -N + NW ⇒ Z = ZW + DA (I -W) + N (I -W) Z = ZW + D Ã + Ñ (7)
Then, we propose to solve the following problem min

W, Ã W 1 + λ Ã 1 s.t. Z = D Ã + ZW diag (W) = 0 (8)
where the 1-norm promotes the sparsity of the matrices W and à and the parameter λ balances the two terms in the criterion.

The problem ( 8) being convex, it can be efficiently solved using convex programming tools [START_REF] Boyd | Convex optimization[END_REF]. On one hand, the class of Accelerated Proximal Gradient algorithms, which are first-order methods, theoretically offers a convergence rate guarantee of O 1/k 2 [START_REF] Nesterov | A method of solving a convex programming problem with convergence rate O 1/k 2[END_REF] but needs, for this aim, an appropriate continuation technique. In practice, it can lead to variations in the convergence rate. On the other hand, the class of ADMM algorithms, which is well-suited for parallel processing, exhibits theoretically a convergence rate guarantee of O (1/k) [START_REF] He | On the O (1/t) convergence rate of alternating direction method[END_REF], but offering more stability in practice. In the simulations, we chose the ADMM approach for the resolution of (8).

IV. APPLICATION TO DETECTION IN NON-STATIONARY JAMMING

In this section, we consider the problem of target detection where the interferences are due to either stationary or non-stationary jammers. where U and Λ are the eigen-decomposition of Rjam. We construct the covariance matrix of the total noise by:

R = JNR Tr (Γ) UΓU H + σ 2 IM ( 10
)
with JNR is the Jammer to Noise Ratio and Γ is a diagonal matrix, such that γ1 = γ2 = 3. Analogously, we define the Signal to Noise Ratio (SNR) by SNR = V 2 σ 2 , where σ 2 is fixed to 1. Finally, the total noise is sampled from a centered circular complex Gaussian distribution CN (0, R). In Fig. 1, a realization of the background response is plotted for all θ in the considered grid.

B. Case 2: non-stationary jammers

For the case of non-stationary jammers, we consider that in the set of K = 50 snapshots, there exists J = 3 homogeneous subpartitions, bounded by the white dotted line in Fig.

C. Compared methods

In the considered application, we compare the following methods:

• the Adaptive Normalized Matched Filter (ANMF), where the covariance learning is based on the Sample Covariance Matrix, computed from the 2M samples surrounding the tested sample, which will serve as secondary data.

• the ANMF, where the covariance learning is using the Tyler's estimator [START_REF] Tyler | A distribution-free M-estimator of multivariate scatter[END_REF] on the 2M samples surrounding the tested sample.

• the RoSuRe-detector [START_REF] Breloy | Robust subspace clustering for radar detection[END_REF][START_REF] Bian | Bi-sparsity pursuit for robust subspace recovery[END_REF], which solves the problem (6) by returning A, from the given observations Z and the considered dictionary D.

• the modification of RoSuRe-detector, denoted by m-RoSuRe and which is obtained by solving the problem (8) and returning Ã, from Z and D. We recall the following relation à = A (I -W).

In order to compare the different methods, the obtained detection map are insightful but not quantitative. Thus, we compute the empirical Probability of Detection (PD) for all the targets and the empirical Probability of False Alarm (PFA) (summed for all the other grid locations) with respect to a threshold. From these quantities, we can compare the Receiver Operating Characteristic (ROC) curve of each detector. In Fig. 3, the normalized detection map, before any thresholding, is plotted for SNR = 9 dB and JNR = 15 dB, obtained with the different methods with a correct choice of λ for the sparse based methods. The choice of λ will be discussed later. All the methods are able to retrieve the locations and the instants of present targets. Nevertheless, the ANMF based methods introduce non negligible sidelodes, which can increase the PFA, unlike the methods using subspace clustering. In addition, we can notice that the latter remove more prominently the jammers impact. It is worth noting that the positions of the estimated and detected targets given by the modification of RoSure are slightly shifted since the target sparse matrix is different from the initial model.

In Fig. 4, we can draw the same conclusions as for Fig. 3. However, the performance of ANMF-based procedure are degraded since the assumptions on secondary data (homogeneity and target-free) are not satisfied. Furthermore, we can see that the clutter cancelation obtained by the clustering methods impacts all the samples, whereas the jammers direction changes over the time.

In Fig. 5, we can see the loss of performance for the ANMF-based methods when the jamming is non-stationary, whereas the RoSuRebased ones seem to be less sensitive and still perform better. While having the best visual detection map, m-RoSuRe seems to reach more slowly a PD close to 1. Indeed, working with à instead of A may introduce some bias in the estimated target positions (recall that à = A (I -W)) . This phenomenon impacts the displayed detection performance as we strictly measure the PD/PFA on the actual positions.

In Fig. 6, we analyse, for the case 2, the influence of the regularization parameter λ, which balance the two 1-norms. We can see that the performance obtained by RoSuRe seems to be quite impervious to λ, unlike the one of m-RoSuRe. Again, it can be explained by the relation à = A (I -W): the dependence of the estimate on both A and W suggest that a careful selection of λ is required to mitigate the performance loss due to the introduced bias. In this paper, we explored a new formulation for the target detection problem by means of subspace clustering approach. We proposed a convex modification of SSC that includes a dictionary. This method exhibits similar performance compared to the standard SSC but uncovers a small performance drop for a PD close to 1 due to a bias introduced on the position estimates by Ã. A correction of this bias is left as prospect for a forthcoming study. Interestingly, theses approaches deal with all the samples at once without assumption on the interferences statistical properties. Hence, they can outperform the classic statistical detection scheme in the case of non-stationary clutter/corrupted samples.

Fig. 1 : 2 j=1d

 12 Fig. 1: Scenario with stationary jammer

2 .

 2 In the first subpartition, the jammers are in θj = 20 o and -20 o with γ1 = γ2 = 3. In the second one, we have θj = 20 o , -45 o and -25 o with γ1 = γ3 = 2 = γ2/2. In the last one, we set θj = 60 o and 20 o with γ1 = γ3 = 3.

Fig. 2 :Fig. 3 :

 23 Fig. 2: Scenario with non-stationary jammer

Fig. 4 :

 4 Fig. 4: Normalized detection map for case 2

Fig. 5 :1

 5 Fig. 5: ROC curve: case 1 = solid line, case 2 = dash-dotted line

ACKNOWLEDGEMENT

The authors thank Assoc. Prof. Vincent Y. F. Tan (National University of Singapore) for the interesting discussions and interactions towards the development of this paper.


Anne Reynes-Delobel

Kay Boyle'

Kay Boyle's early novel sheds light on the literary history of the transatlantic modernist avant-garde

Kay Boyle's early novel sheds light on the literary history of the transatlantic modernist avant-garde

Year Before Last deserves to be rediscovered by students and scholars interested in modernist periodical culture and the literary history of the transatlantic avant-garde.

An editorial and critical success story, the novel did much to advance Boyle's career as one of the promising talents of the expatriate avant-garde. Having been given T.S. Eliot's imprimatur in London, it was first published in London by Faber and Faber in 1932. Almost simultaneously, it was brought out in New York by Jonathan Cape and Harrison Smithwho paid the author an advance of a thousand dollarsand, a few months later, in Paris by Crosby Continental Editions, a series that brought out cheap editions of modernist works. Reviewers praised the novel's poetic quality, mastery of images, and finesse of perception. A critic for The New Republic wrote that it was "as emotionally and rhetorically rich in prose as poetry can be." Over the years, it continued to grow in popularity on both sides of the Atlantic. There was talk of a film adaptation. In 1937, Calmann-Lévy brought out a French translation by Marie-Louise Soupault, the wife of the Surrealist poet, writer and critic Philippe Soupault. The novel's autobiographical plot was inspired by a dramatic episode that took place in January 1926, when Boyle decided to leave Normandy where she had settled three years earlier with her first husband, Richard Brault, to travel to the French Riviera at the invitation of the American poet and editor Ernest Walsh. A few months earlier, Walsh had started a small literary magazine, This Quarter, which he coedited with British artist Ethel Moorhead, who generously provided for the printing and shipping costs. Like other avant-garde "little magazines," This Quarter aimed to support young talent, and in particular the younger generation of Anglo-American modernist writers and artists. As a matter of fact, the journal showed only limited interest in European literary and artistic productionwith the exception of Brancusi and Picabia. Such national preference reflected Walsh's ambition to free the literature of his native country from the shackles of European, and especially British, tradition, and encourage the search for a new poetic and democratic idiom.

The first issue of the magazine was dedicated to Ezra Pound, tireless promoter of the avantgarde and defender of small magazines, and included fiction and poetry by Gertrude Stein, H.D., Ernest Hemingway, Yvor Winters and William Carlos Williams. The number and quality of the contributions, as well as the quality of the paper, illustrations and typography, soon made This Quarter a leading mediator in the Anglo-American literary landscape. Walsh's unflagging editorial fervor was also a key element of its success. According to Boyle's later account of her arrival in Grasse in February 1926, no sooner had she set foot on the station platform, exhausted after her long night's journey in a crowded third-class carriage, than he excitedly started to tell her about his plans for his journal and his enthusiasm for Emmanuel Carnevali's latest book.

If anything, she was entranced. In 1922, shortly before her departure for France, she had worked as an editorial assistant in the New York office of Broom magazine, another American little magazine published in Europe. Owing to the generosity of Broom's American editor, Lola Ridge, she was introduced to Marianne Moore and William Carlos Williams, with whom she formed lifelong friendships. In particular, Williams's search for a new, distinctly "American" poetic idiom was a major source of inspiration for her early experiments in both poetry and prose.

As the days went by, Walsh and Boyle's common interest in the rejuvenation of American letters and their strong mutual attraction blossomed into a romantic relationship, driving an infuriated Ethel Moorhead to deprive Walsh of her financial support. Suddenly finding themselves without a home, they set out on an erratic journey along the coast and into the hinterland, hoping to settle down in a place where Walsh's illness (TB) would not arouse suspicion and stigma. From March till October, Boyle helped Walsh with his editorial activities, typing letters and proofreading manuscripts, and reading aloud to him from the books that piled up to the roof of their old Renault.

Walsh's unfailing belief in the power of literature reverberate in the pages of the novel as well as in a series of poems written in 1926 and 1931, such as "To America" and "For an American," where he is described as "a full swinging river" whose footsteps are "wild valleys thundering under [America's] hills." In other poems, Walsh's figure mingles with those of Eugene Jolas, Robert McAlmon, or Harry Crosby, three Paris-based expatriate editors and publishers, and close friends to Boyle. Along with the superb "The United States," dedicated to William Carlos Williams, these poems create a composite, romantic portrait of the poet-genius fervently engaged in an American literary Risorgimento. Life with Walsh also provided Boyle with material for the 1931 short story "Rest Cure," which narrates a fictional episode in D.H. Lawrence's final days in Vence, in early 1930. This collective and transsubjective view of literary production also permeates Year Before Last. Significantly, the end of the decade was marked by several encounters and collaborations of which the novel bears trace, including Boyle's active contribution to transition magazine, which was launched by Eugene Jolas in 1927 to take over from This Quarter after Walsh's untimely death, and her friendship with Robert McAlmon. The two editors were probably a source of inspiration for Mr. Alaric, whose letters bring Martin Sheehan renewed faith in the relevance of his work. "The poet in Italy" is a thinly veiled reference to Emmanuel Carnevali, and the "American writer" bears strong affinities with Williams.

Another distinct characteristic of the novel is its intertextual and intercultural dimension. Explicit allusions to Pound Eliot, Baudelaire, Poe, Blake, and Cocteau, inform dialogues and descriptions. Other quotes from Joyce, Byron, Poe, Sandburg, Williams, or Mangan are seamlessly woven in the text, as in this passage taken from Williams's In the American Grain:

This was the America with which Martin felt bondage, and the skyscrapers might never have been reared aloft. The country of Pocahuntas : a well-featured, but wanton yong girle, sometimes resorting to our fort, at the age of eleven or twelve, get the boyes forth with her in the market-place, and make them wheele, falling on their hands, turning their heels upward, whome she would followe, and wheele so herself, naked as she was, all the fort over.

In a similar way, throughout the novel, snippets from poems, letters, or novels emerge in a dance step or a song, and erupt from the books, journals, and manuscripts that cover the floors, shelves, and beds, and pile up to the ceiling of Sheehan's car.

If the name of William Carlos Williams has already been mentioned several times in this article, it is because Williams's view of renewed poetic contact with the American soil was understood by such young writers as Boyle, Walsh, and McAlmon as a literary call to arms. According to the hermeneutic approach Williams developed in In the American Grain (1925), true knowledge of the American experience (what Williams called "the hard, sardonic, truculent mass of the New World, hot, angry"), could only be achieved through encounter with other cultures and experiences. In Williams's book, Poe, the literary equivalent of such figures as Daniel Boone, Sam Houston, or Pere Rasles, epitomizes this form of "discovery" of America. Walsh and Boyle could not but embrace this form of cultural transnationalism. In Year Before Last, Irish ballads, Joyce's musical prose, and Carnevali's American-Italian prose and poetry combine with Sandburg's sonic imagery or Poe's funereal accents in a form of composition close to the fugue. This collective, multiple and heterogeneous imaginary points to Martin Sheehan's magazine as the real protagonist of the novel. The (nameless) journal is indeed the constant preoccupation of the characters and the prime mover of the plot. In this respect, the novel also gratifies the reader with an insider's account of the inner workings of modernist little magazines, with their often contradictory imperatives, complex forms ofat times unsocial sociability, blatant sectarianism and elitism, and miraculous, fragile contingency.

The vital energy that gushes out of these pages may render the reader deaf to what characters keep repeating. Let's listen to Martin telling us that he died years ago in a plane crash. Let's pay attention to the numerous ghosts that haunt the story. And for good reason. The end of the twenties marked the dissolution of avant-garde modernism and the decline of literary magazines. The last of them, transition, suspended publication from 1930 to 1932, at the very same time when Boyle was at work on her novel. The rise of political magazines marked the beginning of a new decade, while eyes anxiously turned toward Germany. Soon, Boyle and her family left France for Austria, where they witnessed at first-hand the Anschluss. A spectrographic narrative, the novel nonetheless radiates the petulance, audacity and gaiety of youth, and a stubborn belief in novelty, understood as both individual creation and collective/communal re-creation.

[The original 1932 edition should be preferred to the Virago edition (1986) which bears traces of revisions by the author that are often detrimental to the stylistic idiosyncracies that account for its originality] Anne Reynes-Delobel Adapted from the introduction to the latest French translation of Year Before Last: Fuir avant demain, UGA Editions, 2018.