Cybersickness Influences the Affectieve Appraisal of a Virtual Environment

We investigated if cybersickness has an effect on the affective appraisal of a virtual environment (VE). For many applications it is essential that users experience the simulated environment in a similar way as the corresponding real one. Navigation through VEs is known to negatively influence the physical well-being of observers by inducing cybersickness. Since people tend to misattribute their feelings to the environment they perceive, cybersicknesss may influence their affective appraisal of a VE. Participants passively watched a simulated walk through a VE, while the visual scene continuously performed a quasi-sinusoidal frontal roll oscillation. Immediately after the exposure, they reported their experienced level of cybersickness and assessed the environment on a semantic differential scale. People experiencing cybersickness rated the environment as less pleasant and more arousing, as compared to people with no symptoms. Thus, users suffering from cybersickness misattributed their unpleasant feelings to the affective qualities of the VE. Applications that rely on VEs to evoke the same emotional and affective user responses as their real equivalent should therefore minimise or account for the incidence of cybersicknes

Dynamics of a multi-DOF beam system with discontinuous support

This paper deals with the long term behaviour of periodically excited mechanical systems consisting of linear components and local nonlinearities. The particular system investigated is a 2D pinned-pinned beam, which halfway its length is supported by a one-sided spring and excited by a periodic transversal force. The linear part of this system is modelled by means of the finite element method and subsequently reduced using a Component Mode Synthesis method. Periodic solutions are computed by solving a two-point boundary value problem using finite differences or, alternatively, by using the shooting method. Branches of periodic solutions are followed at a changing design variable by applying a path following technique. Floquet multipliers are calculated to determine the local stability of these solutions and to identify local bifurcation points. Also stable and unstable manifolds are calculated. The long term behaviour is also investigated by means of standard numerical time integration, in particular for determining chaotic motions. In addition, the Cell Mapping technique is applied to identify periodic and chaotic solutions and their basins of attraction. An extension of the existing cell mapping methods enables to investigate systems with many degrees of freedom. By means of the above methods very rich complex dynamic behaviour is demonstrated for the beam system with one-sided spring support. This behaviour is confirmed by experimental results. [Author abstract; 14 Refs; In English

CORRESPONDENCE

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75533/1/j.1471-0528.1980.tb05024.x.pd

Association between postoperative muscle wasting and survival in older patients undergoing surgery for non-metastatic colorectal cancer

BACKGROUND: Preoperative sarcopenia in older patients is a risk factor for adverse outcomes after colorectal cancer (CRC) surgery. Longitudinal changes in muscle mass in this group have not been studied previously although muscle wasting may have prognostic significance regarding survival. We aimed to determine the association between muscle wasting and overall survival (OS) in older patients who underwent surgery for CRC.METHODS: Patients ≥70 years who underwent surgery for non-metastatic CRC in Gelre hospitals, The Netherlands, between 2011 and 2015 were included. Cross-sectional area of skeletal muscle was measured at the level of the 3rd lumbar vertebra on preoperative and postoperative abdominal CT-scans. Patients who had &gt;1 standard deviation decrease in muscle mass were considered to have muscle wasting. Cox regression analysis was used to evaluate associations between muscle wasting and OS.RESULTS: 233 patients were included (40% female, median age 76 years). Thirty-four patients had muscle wasting. After a median follow-up of 4.7 years, 53 (23%) patients died. The 3-year mortality rate was higher in patients with muscle wasting (27% vs 14%, p = .05). In multivariable analysis adjusted for age, recurrent disease and preoperative muscle mass, muscle wasting was associated with reduced OS (HR 2.8, 95% CI 1.5-5.4, p = .002).CONCLUSION: Muscle wasting predicted poorer survival in older patients who underwent CRC surgery. Measuring changes in muscle mass may improve risk prediction in this patient group. Future studies should address the etiology of muscle wasting in older patients with CRC. Whether perioperative exercise interventions can prevent muscle wasting also warrants further study.</p

Time-trends in disease characteristics and comorbidities in patients with chronic hepatitis B in the period 1980–2020

Background & aims: The incidence of chronic hepatitis B (CHB) is declining due to successful implementation of vaccination programs and widespread use of antiviral therapy. We aimed to study time-trends in disease characteristics and comorbidities in newly referred CHB patients. Methods: : We collected information on hepatitis B virus (HBV) related disease characteristics (including hepatitis B e-antigen (HBeAg) status, viremia, stage of liver fibrosis and indication for treatment and/or hepatocellular carcinoma (HCC) surveillance) and presence of comorbidities in all CHB patients referred to our center from 1980 through 2020. Patient characteristics were compared according to referral date (before 2000, between 2000 and 2010 and after 2010). Results: : We identified 1515 eligible patients. Patients referred after 2010 were older (36 versus 34 years, p < 0.001), more often non-Caucasian (82.3% versus 55.0%, p < 0.001) and more frequently HBeAg negative (81.5% versus 49.8%, p < 0.001) when compared to patients referred before 2000. Adjusted for ethnicity, sex and age, patients referred after 2010 were less likely to have significant fibrosis (adjusted odds ratio [aOR]:0.178, p < 0.001) or indication for antiviral therapy (aOR:0.342, p < 0.001) but were more likely to be affected by the metabolic syndrome (aOR:1.985, p = 0.013), hepatic steatosis (aOR:1.727, p < 0.001) and metabolic dysfunction associated fatty liver disease (MAFLD) (aOR:1.438, p = 0.013). Conclusions: : The characteristics of the CHB populations are changing. Newly referred patients are older, have less active HBV related liver disease but are more likely to be co-affected by MAFLD. These findings provide guidance for adequate allocation of resources to cope with the changing characteristics of the CHB population

Spatial tools for diagnosing the degree of safety and liveability, and to regenerate urban areas in the Netherlands

This contribution describes the tool Social Safe Urban Design (SSUD), seen together with socio-spatial and linguistic challenges when applying space syntax in the regenerating of problem urban areas. The Space Syntax jargon is technical and needs to be translated into a language understandable and acceptable to stakeholders who are responsible for the implementation of improvement strategies acceptable for the users of a neighbourhood. Moreover, the degree of public-private interface between buildings and streets needs to be incorporated in the Space Syntax analyses. As it turns out from spatial analyses and crime registrations, there is a correlation between crime and anti-social behaviour and the spatial layout of built environments in the investigated eight pilot cases. Simultaneously, there is also a challenge to come up with locally and globally functioning spatial solutions for reducing opportunities for crime and anti-social behaviour for the neighbourhoods. Proposed solutions for three of these neighbourhoods are presented in this contribution