An improved instrumental variable method for industrial robot model identification

Abstract Industrial robots are electro-mechanical systems with double integrator behaviour, necessitating operation and model identification under closed-loop control conditions. The Inverse Dynamic Identification Model (IDIM) is a mechanical model based on Newton’s laws that has the advantage of being linear with respect to the parameters. Existing Instrumental Variable (IDIM-IV) estimation provides a robust solution to this estimation problem and the paper introduces an improved IDIM-PIV method that takes account of the additive noise characteristics by adding prefilters that provide lower variance estimates of the IDIM parameters. Inspired by the prefiltering approach used in optimal Refined Instrumental Variable (RIV) estimation, the IDIM-PIV method identifies the nonlinear physical model of the robot, as well as the noise model resulting from the feedback control system. It also has the advantage of providing a systematic prefiltering process, in contrast to that required for the previous IDIM-IV method. The issue of an unknown controller is also considered and resolved using existing parametric identification. The evaluation of the new estimation algorithms on a six degrees-of-freedom rigid robot shows that they improve statistical efficiency, with the controller either known or identified as an intrinsic part of the IDIM-PIV algorithm

Time of Day and its Association with Risk of Death and Chance of Discharge in Critically Ill Patients: A Retrospective Study.

Outcomes following admission to intensive care units (ICU) may vary with time and day. This study investigated associations between time of day and risk of ICU mortality and chance of ICU discharge in acute ICU admissions. Adult patients (age ≥ 18 years) who were admitted to ICUs participating in the Austrian intensive care database due to medical or surgical urgencies and emergencies between January 2012 and December 2016 were included in this retrospective study. Readmissions were excluded. Statistical analysis was conducted using the Fine-and-Gray proportional subdistribution hazards model concerning ICU mortality and ICU discharge within 30 days adjusted for SAPS 3 score. 110,628 admissions were analysed. ICU admission during late night and early morning was associated with increased hazards for ICU mortality; HR: 1.17; 95% CI: 1.08-1.28 for 00:00-03:59, HR: 1.16; 95% CI: 1.05-1.29 for 04:00-07:59. Risk of death in the ICU decreased over the day; lowest HR: 0.475, 95% CI: 0.432-0.522 for 00:00-03:59. Hazards for discharge from the ICU dropped sharply after 16:00; lowest HR: 0.024; 95% CI: 0.019-0.029 for 00:00-03:59. We conclude that there are "time effects" in ICUs. These findings may spark further quality improvement efforts

Cytocompatibility of Medical Biomaterials Containing Nickel by Osteoblasts: a Systematic Literature Review

The present review is based on a survey of 21 studies on the cytocompatibility of medical biomaterials containing nickel, as assessed by cell culture of human and animal osteoblasts or osteoblast-like cells. Among the biomaterials evaluated were stainless steel, NiTi alloys, pure Ni, Ti, and other pure metals. The materials were either commercially available, prepared by the authors, or implanted by various techniques to generate a protective layer of oxides, nitrides, acetylides. The observation that the layers significantly reduced the initial release of metal ions and increased cytocompatibility was confirmed in cell culture experiments. Physical and chemical characterization of the materials was performed. This included, e.g., surface characterization (roughness, wettability, corrosion behavior, quantity of released ions, microhardness, and characterization of passivation layer). Cytocompatibility tests of the materials were conducted in the cultures of human or animal osteoblasts and osteoblast-like cells. The following assays were carried out: cell proliferation and viability test, adhesion test, morphology (by fluorescent microscopy or SEM). Also phenotypic and genotypic markers were investigated. In the majority of works, it was found that the most cytocompatible materials were stainless steel and NiTi alloy. Pure Ni was rendered and less cytocompatible. All the papers confirmed that the consequence of the formation of protective layers was in significant increase of cytocompatibility of the materials. This indicates the possible further modifications of the manufacturing process (formation of the passivation layer)

Hepatocellular carcinoma in elderly patients: challenges and solutions

Angélique Brunot, Samuel Le Sourd, Marc Pracht, Julien Edeline Department of Medical Oncology, Centre Eugene Marquis, Rennes, FranceAbstract: Hepatocellular carcinoma (HCC) is the second most common cause of death by cancer in the world. Due to the delayed HCC development in hepatitis C carriers and nonalcoholic fatty liver disease, the incidence of HCC in the elderly is increasing and is becoming a global health issue. Elderly patients with HCC should be assessed through proper oncologic approach, namely, screening tools for frailty (Geriatric-8 or Vulnerable Elders Survey-13) and comprehensive geriatric assessment. This review of the literature supports the same treatment options for elderly patients as for younger patients, in elderly patients selected as fit following proper oncogeriatric assessment. Unfit patients should be managed through a multidisciplinary team involving both oncological and geriatrician professionals. Specific studies and recommendations for HCC in the elderly should be encouraged.Keywords: liver cancer, treatment, surgery, geriatric evaluation, sorafeni

Matrix-assisted UV laser desorption of biopolymers: influence of the interactions in the target

The influence of the nature of the matrix and of the macroscopic structure of the target on the MALD spectra of proteins has been systematically studied for matrices such as 2,5-dihydroxybenzoic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, 3-hydroxy-4-methoxycinnamic acid and α-cyano-4-hydroxycinnamic acid. Only 3,5-dimethoxy-4-hydroxycinnamic has been found to give homogeneous targets and reproducible spectra. The neutral contribution to the protein molecular and cluster peaks, which depends on the the laser fluence and on the mass of the protein, also strongly depends on the nature of the matrix