On the relationship between travel time and travel distance of commuters. Reported versus network travel data in the Netherlands

This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are usually rounded in multiples of five minutes. This calls for special statistical techniques. Ignoring the phenomenon of rounding leads to biased estimation results for shorter distances. Rather surprisingly, the distance as the crow flies and the network distance appear to be slightly better proxies of the reported travel time compared with the shortest network travel time as indicated by the route planner. We conclude that where actual driving times are missing in commuting research the other three indicators mentioned may be used as proxies, but that the following problems may emerge: actual travel times may be considerably higher than network times generated by route planners, and the average speed of trips increases considerably with distance, implying an overestimate of travel time for long distance commuters. The only personal feature that contributes significantly to variations in reported travel times is gender: women appear to drive at lower average speeds according to our data. As indicated in the paper this may be explained by the differences in the car types of male and female drivers (females drive older and smaller cars) as well as higher numbers of stops/trip chaining among women. A concise analysis is carried out for carpoolers. Car-pooling leads to an increase in travel time of some 17% compared with solo drivers covering the same distance. In the case of car poolers, the above mentioned measures appear to be very poor proxies for the actual commuting times

A pilot study into the perception of unreliability of travel times using in-depth interviews

AbstractTransport investments normally reduce travel times, but may also reduce unreliability. Conventional time gains can be evaluated in cost benefit analysis using standard values of time. For valuing reliability gains, however, no standard measures are readily available. The Dutch Ministry of Transport has commissioned a project to design a Stated Preference methodology. Reliability is a complex “academic” concept and it may be difficult to present and explain it to respondents. Therefore, a pilot study using in-depth face-to-face interviews has been carried out, in which various SP choice designs have been presented to the participants to test their understanding of the questions. In the end, we found a “best” design. But still, much care is needed for an acceptable response rate and to prevent illogical and inconsistent responses

Performance engineering for microservices and serverless applications: the RADON approach

Microservices and serverless are becoming integral parts of mod-ern cloud-based applications. Tailored performance engineering isneeded for assuring that the applications meet their requirementsfor quality attributes such as timeliness, resource efficiency, andelasticity. A novel DevOps-based framework for developing mi-croservices and serverless applications is being developed in theRADON project. RADON contributes to performance engineeringby including novel approaches for modeling, deployment optimiza-tion, testing, and runtime management. This paper summarizes thecontents of our tutorial presented at the 11th ACM/SPEC Interna-tional Conference on Performance Engineering (ICPE)

Upper bounds for number of removed edges in the Erased Configuration Model

Models for generating simple graphs are important in the study of real-world complex networks. A well established example of such a model is the erased configuration model, where each node receives a number of half-edges that are connected to half-edges of other nodes at random, and then self-loops are removed and multiple edges are concatenated to make the graph simple. Although asymptotic results for many properties of this model, such as the limiting degree distribution, are known, the exact speed of convergence in terms of the graph sizes remains an open question. We provide a first answer by analyzing the size dependence of the average number of removed edges in the erased configuration model. By combining known upper bounds with a Tauberian Theorem we obtain upper bounds for the number of removed edges, in terms of the size of the graph. Remarkably, when the degree distribution follows a power-law, we observe three scaling regimes, depending on the power law exponent. Our results provide a strong theoretical basis for evaluating finite-size effects in networks

CT-measured skeletal muscle mass used to assess frailty in patients with head and neck cancer

BACKGROUND: Skeletal muscle depletion or sarcopenia is related to multiple adverse clinical outcome. However, frailty questionnaires are currently applied in the daily practice to identify patients who are potentially (un)suitable for treatment but are time consuming and straining for patients and the clinician. Screening for sarcopenia in patients with head and neck cancer (HNC) could be a promising fast biomarker for frailty. Our objective was to quantify sarcopenia with pre-treatment low skeletal muscle mass from routinely obtained neck computed tomography scans at level of third cervical vertebra in patients diagnosed with HNC and evaluate its association with frailty. METHODS: A total of 112 HNC patients with Stages III and IV disease were included from a prospective databiobank. The amount of skeletal muscle mass was retrospectively defined using the skeletal muscle index (SMI). Correlation analysis between SMI and continuous frailty data and the observer agreement were analysed with Pearson's r correlation coefficients. Sarcopenia was present when SMI felt below previously published non-gender specific thresholds (<43.2 cm2 /m2 ). Frailty was evaluated by Geriatrics 8 (G8), Groningen Frailty Indicator, Timed Up and Go test, and Malnutrition Universal Screening Tool. A univariate and multivariate logistic regression analysis was performed for all patients and men separately to obtain odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: The cohort included 82 men (73%) and 30 women (27%), with a total mean age of 63 (±9) years. The observer agreement for cross-sectional measurements was excellent for both intra-observer variability (r = 0.99, P < 0.001) and inter-observer variability (r = 0.98, P < 0.001). SMI correlated best with G8 frailty score (r = 0.38, P < 0.001) and did not differ per gender. Sarcopenia was present in 54 (48%) patients, whereof 25 (46%) men and 29 (54%) women. Prevalence of frailty was between 5% and 54% depending on the used screening tool. The multivariate regression analysis for all patients and men separately isolated the G8 questionnaire as the only independent variable associated with sarcopenia (OR 0.76, 95% CI 0.66-0.89, P < 0.001 and OR 0.76, 95% CI 0.66-0.88, P < 0.001, respectively). CONCLUSIONS: This is the first study that demonstrates that sarcopenia is independently associated with frailty based on the G8 questionnaire in HNC patients. These results suggest that in the future, screening for sarcopenia on routinely obtained neck computed tomography scans may replace time consuming frailty questionnaires and help to select the (un)suitable patients for therapy, which is highly clinically relevant

The integrin expression profile modulates orientation and dynamics of force transmission at cell–matrix adhesions

Integrin adhesion receptors connect the extracellular matrix (ECM) to the cytoskeleton and serve as bidirectional mechanotransducers. During development, angiogenesis, wound healing and cancer progression, the relative abundance of fibronectin receptors, including integrins α5β1 and αvβ3, changes, thus altering the integrin composition of cell-matrix adhesions. Here, we show that enhanced αvβ3 expression can fully compensate for loss of α5β1 and other β1 integrins to support outside-in and inside-out force transmission. α5β1 and αvβ3 each mediate actin cytoskeletal remodeling in response to stiffening or cyclic stretching of the ECM. Likewise, α5β1 and αvβ3 support cellular traction forces of comparable magnitudes and similarly increase these forces in response to ECM stiffening. However, cells using αvβ3 respond to lower stiffness ranges, reorganize their actin cytoskeleton more substantially in response to stretch, and show more randomly oriented traction forces. Centripetal traction force orientation requires long stress fibers that are formed through the action of Rho kinase (ROCK) and myosin II, and that are supported by α5β1. Thus, altering the relative abundance of fibronectin-binding integrins in cell-matrix adhesions affects the spatiotemporal organization of force transmission.Toxicolog

Serum magnesium, hepatocyte nuclear factor 1β genotype and post-transplant diabetes mellitus: a prospective study

BACKGROUND: Retrospective studies suggest that tacrolimus-induced hypomagnesaemia is a risk factor for post-transplant diabetes mellitus (PTDM), but prospective studies are lacking. METHODS: This was a prospective study with measurements of serum magnesium and tacrolimus at pre-specified time points in the first year after living donor kidney transplantation (KT). The role of single nucleotide polymorphisms (SNPs) in hepatocyte nuclear factor 1β (HNF1β) was also explored because HNF1β regulates insulin secretion and renal magnesium handling. Repeated measurement and regression analyses were used to analyse associations with PTDM. RESULTS: In our cohort, 29 out of 167 kidney transplant recipients developed PTDM after 1 year (17%). Higher tacrolimus concentrations were significantly associated with lower serum magnesium and increased risk of hypomagnesaemia. Patients who developed PTDM had a significantly lower serum magnesium trajectory than patients who did not develop PTDM. In multivariate analysis, lower serum magnesium, age and body mass index were independent risk factors for PTDM. In recipients, the HNF1β SNP rs752010 G > A significantly increased the risk of PTDM [odds ratio (OR) = 2.56, 95% confidence interval (CI) 1.05-6.23] but not of hypomagnesaemia. This association lost significance after correction for age and sex (OR = 2.24, 95% CI 0.90-5.57). No association between HNF1β SNPs and PTDM was found in corresponding donors. CONCLUSIONS: A lower serum magnesium in the first year after KT is an independent risk factor for PTDM. The HNF1β SNP rs752010 G > A may add to this risk through an effect on insulin secretion rather than hypomagnesaemia, but its role requires further confirmation

Radiologically Defined Sarcopenia as a Biomarker for Frailty and Malnutrition in Head and Neck Skin Cancer Patients

The aim of this study was to evaluate whether radiologically defined sarcopenia, or a low skeletal muscle index (SMI), could be used as a practical biomarker for frailty and postoperative complications (POC) in patients with head and neck skin cancer (HNSC). This was a retrospective study on prospectively collected data. The L3 SMI (cm2/m2) was calculated with use of baseline CT or MRI neck scans and low SMIs were defined using sex-specific cut-off values. A geriatric assessment with a broad range of validated tools was performed at baseline. POC was graded with the Clavien–Dindo Classification (with a grade of &gt; II as the cut-off). Univariate and multivariable regression analyses were performed with low SMIs and POC as the endpoints. The patients’ (n = 57) mean age was 77.0 ± 9 years, 68.4% were male, and 50.9% had stage III–IV cancer. Frailty was determined according to Geriatric 8 (G8) score (OR 7.68, 95% CI 1.19–49.66, p = 0.032) and the risk of malnutrition was determined according to the Malnutrition Universal Screening Tool (OR 9.55, 95% CI 1.19–76.94, p = 0.034), and these were independently related to low SMIs. Frailty based on G8 score (OR 5.42, 95% CI 1.25–23.49, p = 0.024) was the only variable related to POC. However, POC was more prevalent in patients with low SMIs (∆ 19%, OR 1.8, 95% CI 0.5–6.0, p = 0.356).To conclude, a low SMI is a practical biomarker for frailty and malnutrition in HNSC. Future research should be focused on interventions based on low SMI scores and assess the effect of the intervention on SMI, frailty, malnutrition, and POC.</p