The prediction of hospital length of stay using unstructured data

International audienceObjective: This study aimed to assess the performance improvement for machine learning-based hospital length of stay (LOS) predictions when clinical signs written in text are accounted for and compared to the traditional approach of solely considering structured information such as age, gender and major ICD diagnosis. Methods: This study was an observational retrospective cohort study and analyzed patient stays admitted between 1 January to 24 September 2019. For each stay, a patient was admitted through the Emergency Department (ED) and stayed for more than two days in the subsequent service. LOS was predicted using two random forest models. The first included unstructured text extracted from electronic health records (EHRs). A word-embedding algorithm based on UMLS terminology with exact matching restricted to patient-centric affirmation sentences was used to assess the EHR data. The second model was primarily based on structured data in the form of diagnoses coded from the International Classification of Disease 10th Edition (ICD-10) and triage codes (CCMU/GEMSA classifications). Variables common to both models were: age, gender, zip/postal code, LOS in the ED, recent visit flag, assigned patient ward after the ED stay and short-term ED activity. Models were trained on 80% of data and performance was evaluated by accuracy on the remaining 20% test data. Results: The model using unstructured data had a 75.0% accuracy compared to 74.1% for the model containing structured data. The two models produced a similar prediction in 86.6% of cases. In a secondary analysis restricted to intensive care patients, the accuracy of both models was also similar (76.3% vs 75.0%). Conclusions: LOS prediction using unstructured data had similar accuracy to using structured data and can be considered of use to accurately model LOS

An insight into mechanical properties of heartwood and sapwood of large French Douglas-fir LVL

The French resource of large diameter Douglas fir is currently still growing, while these large diameter trees are complicated to process efficiently by the sawmilling industry. The rotary peeling process appeared to be particularly adapted as an alternative to the usual sawing. This primary processing method produces veneers used to make a wood engineered product material called Laminated Veneer Lumber (LVL). The manufacturing process of LVL enables the distribution of the resource defects, allowing for increased mechanical behaviour compared to the solid wood from which it comes from. The main objective of this study is to provide an insight into the principal Douglas-fir heartwood LVL mechanical properties such as longitudinal and shear moduli of elasticity, bending, shear and compressive strengths. Up to now, there was no study on LVL derived from this resource. This study focuses on heartwood because of its very interesting natural durability properties for constructive outdoor applications. Moreover, a comparison with structural timber properties and a comparable industrial engineering product, made of Norway spruce and called Kerto© S was also achieved to place the material in terms of mechanical performance among the market. Globally, this Douglas-fir heartwood LVL showed high compressive and shear properties. Even though the bending properties were significantly lower than data from Douglas-fir LVL of the literature, they seemed appropriate for structural applications. A larger experimental campaign fully representative of the industrial process and dealing with larger samples will be needed to finally conclude on the characteristic values to be used in structural design. © 202

Bending, shearing, and compression properties of fast growing French Douglas fir LVL

The French resource of large diameter Douglas fir is currently keeping growing, while these large diameter trees are complicated to process efficiently by the sawmilling industry. The rotary peeling process appeared to be particularly adapted as an alternative to the usual sawing. This primary processing method produces veneers used to make a wood engineering product material called Laminated Veneer Lumber (LVL). The manufacturing process of LVL enables the distribution of the resource defects, allowing for increased mechanical behaviour compared to the solid wood from which it comes from. The main objective of this study is to present the principal Douglas-fir heartwood LVL mechanical properties such as longitudinal and shear moduli of elasticity, bending, shear and compressive strengths. Up to now, there were no study on LVL derived from this resource. This study focuses on heartwood because of its very interesting natural durability properties for constructive outdoor applications. Moreover, a comparison with structural timber properties was also achieved to place the material in terms of mechanical performance among the market. Globally, this LVL material showed high compressive and shear properties. Nevertheless, even though the bending properties were significantly lower than data from Douglas-fir LVL literature, they are still quite acceptable for structural applications. © WCTE 2021. All rights reserved

Covalent association of a ruthenium-based chromophore and a copper catalyst: A synergy for sulfides photo-oxidation

International audienceThe development of catalytic systems for the oxidation of organic substrates using renewable sources such as water and dioxygen remains challenging. In this paper we report the synthesis and full characterization of a new dyad combining a ruthenium(II)-based chromophore and a bio-inspired copper(II) pre-catalyst. In particular, photo-induced electron transfer from the photosensitized Ru$^{II}$ subunit toward the Cu$^{II}$ center is highlighted. The photogenerated Cu$^I$ moiety proves to be catalytically efficient for sulfides oxidation by $^3$O$_2$ in the presence of a sacrificial electron source. Finally, the covalent association of the two partners favors Cu/O$_2$-based catalysis at the expense of a $^1$O$_2$-centered reactivity for a bimolecular mixture