Synthèse bibliographique : l'écologie chimique des coccinelles

Review: chemical ecology of ladybird beetles. This paper reviews the chemical ecology of ladybird beetles (Coleoptera: Coccinellidae) to present the role of semiochemicals involved in plant-ladybird, prey-ladybird and predator-ladybird interactions. Ladybird beetles use these compounds to locate their prey, mate, protect themselves from predation or cannibalism, find a shelter to overwinter or ensure a better survival for their offspring. Thorough studies on ladybird behaviors towards these compounds could lead to their practical implementation in integrated strategies using ladybirds to control pests, like aphids or mealybugs

Tensor completion in hierarchical tensor representations

Compressed sensing extends from the recovery of sparse vectors from undersampled measurements via efficient algorithms to the recovery of matrices of low rank from incomplete information. Here we consider a further extension to the reconstruction of tensors of low multi-linear rank in recently introduced hierarchical tensor formats from a small number of measurements. Hierarchical tensors are a flexible generalization of the well-known Tucker representation, which have the advantage that the number of degrees of freedom of a low rank tensor does not scale exponentially with the order of the tensor. While corresponding tensor decompositions can be computed efficiently via successive applications of (matrix) singular value decompositions, some important properties of the singular value decomposition do not extend from the matrix to the tensor case. This results in major computational and theoretical difficulties in designing and analyzing algorithms for low rank tensor recovery. For instance, a canonical analogue of the tensor nuclear norm is NP-hard to compute in general, which is in stark contrast to the matrix case. In this book chapter we consider versions of iterative hard thresholding schemes adapted to hierarchical tensor formats. A variant builds on methods from Riemannian optimization and uses a retraction mapping from the tangent space of the manifold of low rank tensors back to this manifold. We provide first partial convergence results based on a tensor version of the restricted isometry property (TRIP) of the measurement map. Moreover, an estimate of the number of measurements is provided that ensures the TRIP of a given tensor rank with high probability for Gaussian measurement maps.Comment: revised version, to be published in Compressed Sensing and Its Applications (edited by H. Boche, R. Calderbank, G. Kutyniok, J. Vybiral

‘Wellness’ lifts us above the Food Chaos’: a narrative exploration of the experiences and conceptualisations of Orthorexia Nervosa through online social media forums

The increasing prevalence of eating disorders has motivated a burgeoning of research from narrative methods to illuminate the cultural and social aspects of disordered eating habits. A seemingly new eating disorder, Orthorexia Nervosa, has gained visibility through the internet sphere and popular media, though scholarly attention has been scarce. This study develops qualitative understandings of the fixation with ‘clean eating’ through narrative inquiry by employing an internet ethnographic approach. Data were analysed using a thematic narrative analysis, focusing on parallels and divergences across narratives presented online. This article presents 30 male and female voices, illustrating how these individuals understand their eating habits through narratives of pursuit, resistance and recovery, which are largely motivated by the desire for physical, emotional and social change. Crucially, this study illuminates a range of cultural elements enabling eating disorders in response to the transmission of cultural values online set within the broader context and processes of reflexive-modernisation

A procedurális emlékezet szerepe a testkép zavaraiban = The role of procedural memory in trouble of body picture

Az evészavarok egyik vezető betegségfenntartó tényezője a betegek torzult, diszfunkcionális kogníciója. Ezen belül is kiemelendők a táplálékfelvételi viselkedés zavaraival és a testélménnyel kapcsolatban lévő, a zavarok létrejöttében kulcsszerepet játszó kognitív disztorziók, melyek az információfeldolgozási folyamatokon belül elsősorban a perceptuális élményfeldolgozást érintik és evészavaros betegeknél a testkép speciális zavarában mutatkoznak meg. A kognitív információfeldolgozást a sémák irányítják, amelyekben a selfről való komplex tudás szerveződik. A sémák procedurális ismeretanyagot is hordoznak, úgy mint motoros készségeket, szokásokat, szabályokat, célképzeteket, döntéshozatali stratégiákat. Ezek alapján felmerül, hogy az evészavarokra jellemző viselkedéses rutincselekvések, mint például a diétázás, falásroham, önhánytatás a testkép sémáján belül procedurális élményanyagként kódolódhat és a munkamemóriában automatikusan a többi explicit tudással és emlékkel együtt aktiválódik. Elméleti áttekintésünkben ezeknek a prekognitív folyamatoknak keressük a helyét és szerepét az evészavaros betegekre jellemző kognitív információfeldolgozási jellegzetességek kialakításában

Orthorexic tendencies are linked with difficulties with emotion identification and regulation.

Background: Orthorexia nervosa (ON) is characterised by an unhealthy obsession with healthy eating and while it is not recognised as an eating disorder (or any disorder), current research is exploring similarities and differences with such disorders. The literature has shown that individuals with eating disorders have difficulties identifying and describing emotions (known as alexithymia) as well as regulating them. However no research to date has looked at whether people with orthorexic tendencies also suffer from difficulties with emotions. In this paper, we refer to people with orthorexic tendencies but do not assume that their healthy eating is at a pathological level needing clinical attention. Methods: The current study examined this by asking 196 healthy adults with an interest in healthy eating to complete four questionnaires to measure ON (ORTO-15 - reduced to ORTO-7CS), eating psychopathology (EAT-26), alexithymia (TAS-20) and emotion dysregulation (DERS-16). Results: We found that difficulties identifying and regulating emotions was associated with symptoms of ON, similar to what is found in other eating disorders. We suggest that ON behaviours may be used as a coping strategy in order to feel in control in these participants who have poor emotion regulation abilities. Conclusions: Our results show that individuals with ON tendencies may share similar difficulties with emotions compared to other eating disorders. While important, our results are limited by the way we measured ON behaviours and we recommend that further research replicate our findings once a better and more specific tool is developed and validated to screen for ON characteristics more accurately

Behandeling en stigmamanagement bij opzettelijke zelfverwonding: het smalle pad tussen te veel en te weinig interveniëren

Opzettelijke zelfverwonding wordt gedefinieerd als de intentionele directe beschadiging van het eigen lichaam, zonder bewuste suïcidale intentie. De behandeling varieert van gedwongen opname in een psychiatrische instelling (in het Britse Gemenebest), tot een permissieve aanpak zonder behandeling en uiteenlopende behandelingsmogelijkheden er tussenin. Eerst wordt de gepastheid van de mate van interveniëren besproken in functie van verschillende diagnosen. Het tweede gedeelte van het artikel bespreekt het advies dat door hulpverleners verstrekt wordt aangaande de omgang met wonden en littekens en aangaande de mogelijkheden voor een (gewezen) zelfverwonder om het stigma van een deviante identiteit te vermijden. Een rondvraag bij Belgische hulpverleners bracht aan het licht dat velen onder hen adviseren om littekens te verbergen, terwijl er anderzijds aanwijzingen zijn dat niet-verbergen een teken van herstel is. Aangezien verbergen en smoesjes verzinnen ook kunnen leiden tot de instandhouding van een deviante identiteit, wordt gewezen op meer gepaste vormen van stigmamanagement

Geometric methods on low-rank matrix and tensor manifolds

In this chapter we present numerical methods for low-rank matrix and tensor problems that explicitly make use of the geometry of rank constrained matrix and tensor spaces. We focus on two types of problems: The first are optimization problems, like matrix and tensor completion, solving linear systems and eigenvalue problems. Such problems can be solved by numerical optimization for manifolds, called Riemannian optimization methods. We will explain the basic elements of differential geometry in order to apply such methods efficiently to rank constrained matrix and tensor spaces. The second type of problem is ordinary differential equations, defined on matrix and tensor spaces. We show how their solution can be approximated by the dynamical low-rank principle, and discuss several numerical integrators that rely in an essential way on geometric properties that are characteristic to sets of low rank matrices and tensors

Are recovery stories helpful for women with eating disorders? A pilot study and commentary on future research

Background: Anecdotally it is well known that eating disorder memoirs are popular with people with anorexia nervosa and recovery stories are readily available online. However, no research to date has empirically explored whether such stories are helpful for current sufferers. The aim of the current pilot study was to explore the efficacy of recovery narratives as a means of improving motivation and self-efficacy and to qualitatively explore patient perspectives of such stories. Method: Fifty-seven women with anorexia nervosa and subclinical anorexia nervosa participated in this online study. Participants were randomised to either receive recovery stories or to a wait-list control group. After completing baseline measures, participants read five stories about recovery, and completed post-intervention measures two weeks later. Results: The quantitative results indicated that reading stories of recovery had no effect on motivation and self-efficacy over a two-week period. In contrast, the qualitative results showed that the stories generated thoughts about the possibility of recovery and the majority indicated they would recommend them to others. Conclusions: This study adds to a growing body of research exploring the integration of voices of lived experience into treatment approaches. Future research should focus on 1) identifying for whom and at which stage of illness recovery stories might be helpful; 2) the mechanism via which they might operate; and 3) the most helpful way of presenting such stories