Synthesis and properties of composites of starch and chemically modified natural rubber

A means is developed for forming polysaccharide-based composites with useful material properties through use of unmodified and chemically modified natural rubber latex (NRL). Starch was used as a model for polysaccharides. The NRL was modified by grafting with dimethylaminoethyl methacrylate (DMAEMA) to form a latex with cationic water-soluble polymeric “hairs” of polyDMAEMA, which should form hydrogen bonds with starch. Starch solutions, containing 20% glycerol as a film-forming aid, and the modified NRL were mixed and films allowed to form. The unmodified latex acted only as filler in the starch films, but with modified NRL, the mechanical properties of the films were significantly altered. The elastic modulus was greatly decreased and strain at break greatly increased. The glass transition temperature increased from –48°C to –32°C, suggesting significant compatibilization. Freeze-fracture TEM micrographs indicate strong interactions between the surface of the modified NRL and starch. The polyDMAEMA chains are more hydrophilic than the starch, and the addition of grafted latex results in a 20° drop of the water contact angle of the formed film, and a 25% increase of the water absorption compared to the native starch; with unmodified NRL, the opposite effect was observed

Capital Utilisation and Retirement

This empirical analysis aims at assessing the effect of the economic climate and the intensity of capital utilisation on companies' capital retirement behaviour. It is conducted using individual company data, as well as original data on the degree of utilisation of production factors. The sample includes 6,998 observations over the period 1996-2008. This database is, to our knowledge, unique for the empirical analysis of the intensity of capital utilisation on firms' capital retirement behaviour. We adjust for endogeneity biases by means of instrumental variables. The main results obtained from the estimation of capital retirement models may be summarised as follows: i) The retirement rate decreases with the variations in cyclical pressures measured by the changes in output and the workweek of capital; this relation corresponds to a countercyclical decelerator effect on capital retirement; ii) The capital retirement rate increases with the structural intensity of capital utilisation; this effect, which corresponds to a wear and tear one, is nevertheless small compared to the decelerator one; iii) The profit rate does not have a significant impact on the retirement rate. Compared with the existing literature, here mainly Mairesse and Dormont (1985), the contribution of these results is to show, through the use of unique survey data, that the effect of the intensity of capital utilisation on capital retirement is structurally positive, via a wear and tear effect, and cyclically negative, via a decelerator effect which completes that already taken into account via the effect of changes in value added.Capital; Capital measure; Capital retirement; Capital utilisation

Capital Utilisation and Retirement

This empirical analysis aims at assessing the effect of the economic climate and the intensity of capital utilisation on companies' capital retirement behaviour. It is conducted using individual company data, as well as original data on the degree of utilisation of production factors. The sample includes 6,998 observations over the period 1996-2008. This database is, to our knowledge, unique for the empirical analysis of the intensity of capital utilisation on firms' capital retirement behaviour. We adjust for endogeneity biases by means of instrumental variables. The main results obtained from the estimation of capital retirement models may be summarised as follows: i) The retirement rate decreases with the variations in cyclical pressures measured by the changes in output and the workweek of capital; this relation corresponds to a countercyclical decelerator effect on capital retirement; ii) The capital retirement rate increases with the structural intensity of capital utilisation; this effect, which corresponds to a wear and tear one, is nevertheless small compared to the decelerator one; iii) The profit rate does not have a significant impact on the retirement rate. Compared with the existing literature, here mainly Mairesse and Dormont (1985), the contribution of these results is to show, through the use of unique survey data, that the effect of the intensity of capital utilisation on capital retirement is structurally positive, via a wear and tear effect, and cyclically negative, via a decelerator effect which completes that already taken into account via the effect of changes in value added

Inexperienced decision-makers' use of positive heuristics for marketing decisions

Purpose: Research has reliably demonstrated that decision-makers, especially expert ones, use heuristics to make decisions under uncertainty. However, whether decision-makers with little or no experience also do, and if so, how? is unknown. This research addresses this issue in the marketing context by studying how a group of young and generally inexperienced entrepreneurs decide when asked to set a price and choose a distribution channel in a scenario involving a hypothetical firm. Design/methodology/approach: The authors used think-aloud protocols to elicit data and then used inductive procedures to code the data for analysis. Findings: The inexperienced entrepreneurs in the sample used three types of heuristics in their decision-making, forming a structured process that narrows in scope. First, metacognitive heuristics, which specify a decision-making approach, were used, followed by heuristics representing the criteria they considered, and finally, heuristics detailing the execution of a selected option. The authors also found that heuristics relating to a market orientation, especially customer-centric criteria, were the most common, but these were balanced with ones representing an internal orientation or growth. Research limitations/implications: The generally inexperienced decision-makers the authors’ studied used heuristics in a structured way that helped them to select and balance several potentially conflicting decision-making criteria. As with most research using qualitative research designs, the generalizability of these findings is unclear. Further research on the mechanisms by which relatively inexperienced decision-makers learn the heuristics they use is recommended. Originality/value: This research's novelty lies in its focus on heuristic use by nonexpert decision-makers under conditions of uncertainty and the findings about their scope and the order they are used. As the authors collected data from think-aloud protocols with relatively young entrepreneurs with limited experience, they also offer a description of the heuristics used by nascent entrepreneurs when making marketing decisions about pricing and channels. The most surprising conclusion is that even without relevant domain-specific knowledge, decision-makers can use heuristics in an ecologically rational way (i.e. structured to match the environment).Peer reviewe

Figurer la différence : la représentation de soi et de l’autre dans la bande dessinée contemporaine, de Guy Delisle à Joe Sacco

Ce mémoire de maîtrise porte sur les quatre récits de voyage de Guy Delisle, soit Shenzhen (2000), Pyongyang (2003), Chroniques birmanes (2007) et Chroniques de Jérusalem (2011), ainsi que sur un certain nombre de BD reportages de Joe Sacco1, c’est-à-dire Gaza 1956 : en marge de l’histoire (2010), Palestine (2010) et Reportages (2011). Les objectifs de ce travail se déclinent en trois volets principaux : expliciter le fonctionnement de l’autoreprésentation mise en place par les deux auteurs, étudier de quelle manière ces derniers mettent à contribution les ressources narratives de la bande dessinée pour raconter leurs histoires et rendre compte de la charge politique que recèle la « nécessaire médiation » (Pierre Ouellet) ici à l’oeuvre entre une subjectivité et une culture étrangère représentée. On retrouve chez Guy Delisle et Joe Sacco un « je » autobiographique, construit comme tel, auquel il faut aussi ajouter une forme d’autoportrait, puisqu’à l’intérieur même de leurs bandes dessinées, les auteurs se dessinent eux-mêmes et affirment de cette façon le regard singulier et subjectif qu’ils posent sur l’environnement culturel et social. Les bédéistes à l’étude mettent à contribution de nombreuses ressources narratives propres à la bande dessinée pour raconter leurs histoires. C’est en analysant la structure des récits, de même que leurs caractéristiques esthétiques et les effets qu’elles sont censées produire, qu’un portrait d’ensemble sera dressé afin de comparer l’approche respective des deux bédéistes. Ils sont aussi amenés à parler de l’autre et à l’autre, à l’individu qui porte simplement un bagage culturel différent. Les auteurs alimentent donc leurs méthodes de représentation dans un répertoire plus ou moins large, et cette recherche sera l’occasion de voir comment ils réutilisent, assument ou révisent certaines idées préconçues au sujet d’un pays donné. Autrement dit, de quelle manière organisent-ils la « nécessaire médiation » évoquée plus haut, celle entre leur propre subjectivité et une culture étrangère représentée ? Cette question amène à considérer la charge politique que recèlent ces ouvrages

Integrating workload smoothing and inventory reduction in three intermodal logistics platforms of a European car manufacturer

We consider the optimization of container loading at three intermodal logistics platforms (ILP) of a large European car manufacturer (ECM). The decisions focus both on the loading day of each container and on its filling with the products in inventory, which are gradually received over the week from inland suppliers. The objective is either to reduce the largest inventory level needed in the ILP, or to smooth the weekly workload. We develop a solution methodology that allows the handling of complex loading constraints related to dimensions and weight of the products. We model the problem as a mixed integer linear program and we develop a decomposition heuristic to solve it. We perform extensive computation tests on real instances provided by ECM. Compared with current industrial practices, our solutions yield an average improvement of 46.8% for the inventory reduction and of 25.8% for the smoothing of the workload. Our results highlight the benefit of jointly optimizing container loading and operations scheduling.</p

Inbound and outbound flow integration for cross-docking operations

We consider the optimization of the cross-docking operations at three INtermodal LOgistics Platforms (INLOPs) of a large European car manufacturer (ECM). The planning horizon is a week and the time bucket is a day. An inbound flow of products is gradually received over the week by truck from inland suppliers, and has to be loaded into containers which are then shipped to offshore production plants. The full content of a container must be available at the INLOP to enable its loading operations to start, hence temporary storage is needed. The objective is to minimize an inventory penalty, computed as the largest daily volume of temporary product storage observed over the planning horizon. The current practice at ECM is to first optimize the content of the inbound trucks and of the outbound containers independently, and then determine the loading day of each container to be shipped based on these fixed contents. We propose to integrate, within the same optimization framework, the decisions on both truck and container contents, which involve complex loading constraints related to the dimensions and weights of the products, with those on the scheduling of container loading. We model the resulting problem as a mixed integer linear program, and we develop a decomposition scheme for it, as well as a fix-and-optimize matheuristic. We perform extensive computational experiments on real instances provided by ECM. Results show that a combination of these two matheuristics is able to generate solutions that reduce the average inventory penalty by 40%.</p

Combining the hospital frailty risk score with the Charlson and Elixhauser multimorbidity indices to identify older patients at risk of poor outcomes in acute care

Objective: The Hospital Frailty Risk Score (HFRS) can be applied to medico-administrative datasets to determine the risks of 30-day mortality and long length of stay (LOS) in hospitalized older patients. The objective of this study was to compare the HFRS with Charlson and Elixhauser comorbidity indices, used separately or combined. Design: A retrospective analysis of the French medical information database. The HFRS, Charlson index, and Elixhauser index were calculated for each patient based on the index stay and hospitalizations over the preceding 2 years. Different constructions of the HFRS were considered based on overlapping diagnostic codes with either Charlson or Elixhauser indices. We used mixed logistic regression models to investigate the association between outcomes, different constructions of HFRS, and associations with comorbidity indices. Setting: 743 hospitals in France. Participants: All patients aged 75 years or older hospitalized as an emergency in 2017 (n=1,042,234). Main outcome measures: 30-day inpatient mortality and LOS >10 days. Results: The HFRS, Charlson, and Elixhauser indices were comparably associated with an increased risk of 30-day inpatient mortality and long LOS. The combined model with the highest c-statistic was obtained when associating the HFRS with standard adjustment and Charlson for 30-day inpatient mortality (adjusted c-statistics: HFRS=0.654; HFRS + Charlson = 0.676) and with Elixhauser for long LOS (adjusted c-statistics: HFRS= 0.672; HFRS + Elixhauser =0.698). Conclusions: Combining comorbidity indices and HFRS may improve discrimination for predicting long LOS in hospitalized older people, but adds little to Charlson’s 30-day inpatient mortality risk

Assessing Quality-Diversity Neuro-Evolution Algorithms Performance in Hard Exploration Problems

A fascinating aspect of nature lies in its ability to produce a collection of organisms that are all high-performing in their niche. Quality-Diversity (QD) methods are evolutionary algorithms inspired by this observation, that obtained great results in many applications, from wing design to robot adaptation. Recently, several works demonstrated that these methods could be applied to perform neuro-evolution to solve control problems in large search spaces. In such problems, diversity can be a target in itself. Diversity can also be a way to enhance exploration in tasks exhibiting deceptive reward signals. While the first aspect has been studied in depth in the QD community, the latter remains scarcer in the literature. Exploration is at the heart of several domains trying to solve control problems such as Reinforcement Learning and QD methods are promising candidates to overcome the challenges associated. Therefore, we believe that standardized benchmarks exhibiting control problems in high dimension with exploration difficulties are of interest to the QD community. In this paper, we highlight three candidate benchmarks and explain why they appear relevant for systematic evaluation of QD algorithms. We also provide open-source implementations in Jax allowing practitioners to run fast and numerous experiments on few compute resources.Comment: GECCO 2022 Workshop on Quality Diversity Algorithm Benchmark