Transiently Consistent SDN Updates: Being Greedy is Hard

The software-defined networking paradigm introduces interesting opportunities to operate networks in a more flexible, optimized, yet formally verifiable manner. Despite the logically centralized control, however, a Software-Defined Network (SDN) is still a distributed system, with inherent delays between the switches and the controller. Especially the problem of changing network configurations in a consistent manner, also known as the consistent network update problem, has received much attention over the last years. In particular, it has been shown that there exists an inherent tradeoff between update consistency and speed. This paper revisits the problem of updating an SDN in a transiently consistent, loop-free manner. First, we rigorously prove that computing a maximum (greedy) loop-free network update is generally NP-hard; this result has implications for the classic maximum acyclic subgraph problem (the dual feedback arc set problem) as well. Second, we show that for special problem instances, fast and good approximation algorithms exist

Determinants of inpatient rehabilitation length of stay and discharge modality after hip and knee replacement surgery in Switzerland : a retrospective observational study

QUESTIONS UNDER STUDY / PRINCIPLES: The aims of this study were to identify the determinants influencing the inpatient rehabilitation length of stay (LoS) and discharge modality (DisMod) after hip or knee replacement surgery. METHODS: Data were retrieved for 306 patients (185 females, 121 males) who were admitted to a Swiss orthopaedic rehabilitation facility between 2007 and 2008 after hip or knee replacement surgery. LoS and DisMod were extracted from the medical files along with an additional seven binary and six continuous variables (including scores of timed-get-up-and-go [TUG], walking distance [WDT] and stair climbing tests [FIM_St]). Nonparametric procedures were used to detect differences between the gender groups. For the analysis of the LoS determinants, a linear regression model was used. The nonmotor performance test determinants of DisMod were analysed using a logistic regression model, whereas the motor performance test determinants were examined using binary classification. For both regression models, a backward procedure was used. RESULTS: Unlike DisMod, LoS calculations were conducted after stratification for gender. The simplified regression models explained 22% (females) and 31% (males) of the LoS variance and 20% (both genders) of the DisMod variance. TUG, WDT and FIM_St were all important predictors for LoS, whereas DisMod could be best predicted by WDT. CONCLUSIONS: Patients with good motor ability at admission were discharged earlier and more frequently to home. These findings might be of importance for preoperative physiotherapeutic care and might help to improve care planning as well as more accurately predict the access to inpatients beds and the allocation of resources

Dynamics of Blockchain Implementation - A Case Study from the Energy Sector

This case study analyzes the impact of theory-based factors on the implementation of different blockchain technologies in use cases from the energy sector. We construct an integrated research model based on the Diffusion of Innovations theory, institutional economics and the Technology-Organization-Environment framework. Using qualitative data from in-depth interviews, we link constructs to theory and assess their impact on each use case. Doing so we can depict the dynamic relations between different blockchain technologies and the energy sector. The study provides insights for decision makers in electric utilities, and government administrations

How do patients, politicians, physiotherapists and other health professionals view physiotherapy research in Switzerland? A qualitative study

Background. Since 2002, the professional education for Swiss physiotherapists has been upgraded to a tertiary educational level. With this change, the need for research related to professional practice has become more salient. The elaboration of research priorities is seen as a possible way to determine the profession’s needs, to help coordinate research collaborations and to address expectations regarding physiotherapy. There is still limited evidence about stakeholders’ views with regard to physiotherapy research. The objective of this study was to investigate key stakeholders’ opinions about research in physiotherapy in Switzerland. Methods. Focus groups with patients, health professionals, researchers and representatives of public health organizations were conducted, and semi-structured interviews were conducted with politicians, health insurers and medical doctors from three linguistic regions in Switzerland. An interview guide was elaborated. Data were transcribed and analysed using inductive content analysis (Atlas-ti 6W). Results. Eighteen focus groups and 23 interviews/written commentaries included 134 participants with various research experiences and from different settings. Fourteen categories were defined reflecting three themes: identity, interdisciplinarity and visibility. Stakeholders had positive views about the profession and perceived physiotherapists’ important role now and in the future. Yet, they also felt that physiotherapy was not sufficiently recognized in society and not visible enough. A stronger professional identity would be key to enhancing interdisciplinary work. Conclusions. Results of this qualitative study provide insights into key aspects for moving the physiotherapy profession forward. Identity is at the heart of physiotherapy, not necessarily in terms of research priorities but in the definition of domains of competence and future positioning. Identity is also tightly connected to Interdisciplinarity as this might threaten the existence of the profession. Stakeholders outside the profession insist on the importance of visibility. The results of this study can help stakeholders reflect on the future of physiotherapy and elaborate research priorities. Keywords interdisciplinary; physiotherapy; policy; qualitative research; research prioritie

11C-Methionine-PET in multiple myeloma: a combined study from two different institutions

$^{11}$C-methionine (MET) has recently emerged as an accurate marker of tumor burden and disease activity in patients with multiple myeloma (MM). This dual-center study aimed at further corroboration of the superiority of MET as positron emission tomography (PET) tracer for staging and re-staging MM, as compared to $^{18}$F-2`-deoxy-2`-fluoro-D-glucose (FDG). 78 patients with a history of solitary plasmacytoma (n=4), smoldering MM (SMM, n=5), and symptomatic MM (n=69) underwent both MET- and FDG-PET/computed tomography (CT) at the University Centers of Würzburg, Germany and Navarra, Spain. Scans were compared on a patient and on a lesion basis. Inter-reader agreement was also evaluated. In 2 patients, tumor biopsies for verification of discordant imaging results were available. MET-PET detected focal lesions (FL) in 59/78 subjects (75.6%), whereas FDG-PET/CT showed lesions in only 47 patients (60.3%; p<0.01), accordingly disease activity would have been missed in 12 patients. Directed biopsies of discordant results confirmed MET-PET/CT results in both cases. MET depicted more FL in 44 patients (56.4%; p<0.01), whereas in two patients (2/78), FDG proved superior. In the remainder (41.0%, 32/78), both tracers yielded comparable results. Inter-reader agreement for MET was higher than for FDG (κ = 0.82 vs κ = 0.72). This study demonstrates higher sensitivity of MET in comparison to standard FDG to detect intra- and extramedullary MM including histologic evidence of FDG-negative, viable disease exclusively detectable by MET-PET/CT. MET holds the potential to replace FDG as functional imaging standard for staging and re-staging of MM

Abnormal P‐wave terminal force in lead V 1 is a marker for atrial electrical dysfunction but not structural remodelling

Aims There is a lack of diagnostic and therapeutic options for patients with atrial cardiomyopathy and paroxysmal atrial fibrillation. Interestingly, an abnormal P-wave terminal force in electrocardiogram lead V1 (PTFV1) has been associated with atrial cardiomyopathy, but this association is poorly understood. We investigated PTFV1 as a marker for functional, electrical, and structural atrial remodelling. Methods and results Fifty-six patients with acute myocardial infarction and 13 kidney donors as control cohort prospectively underwent cardiac magnetic resonance imaging to evaluate the association between PTFV1 and functional remodelling (atrial strain). To further investigate underlying pathomechanisms, right atrial appendage biopsies were collected from 32 patients undergoing elective coronary artery bypass grafting. PTFV1 was assessed as the product of negative P-wave amplitude and duration in lead V1 and defined as abnormal if ≥4000 ms*μV. Activity of cardiac Ca/calmodulin-dependent protein kinase II (CaMKII) was determined by a specific HDAC4 pull-down assay as a surrogate for electrical remodelling. Atrial fibrosis was quantified using Masson's trichrome staining as a measure for structural remodelling. Multivariate regression analyses were performed to account for potential confounders. A total of 16/56 (29%) of patients with acute myocardial infarction, 3/13 (23%) of kidney donors, and 15/32 (47%) of patients undergoing coronary artery bypass grafting showed an abnormal PTFV1. In patients with acute myocardial infarction, left atrial (LA) strain was significantly reduced in the subgroup with an abnormal PTFV1 (LA reservoir strain: 32.28 ± 12.86% vs. 22.75 ± 13.94%, P = 0.018; LA conduit strain: 18.87 ± 10.34% vs. 10.17 ± 8.26%, P = 0.004). Abnormal PTFV1 showed a negative correlation with LA conduit strain independent from clinical covariates (coefficient B: −7.336, 95% confidence interval −13.577 to −1.095, P = 0.022). CaMKII activity was significantly increased from (normalized to CaMKII expression) 0.87 ± 0.17 to 1.46 ± 0.15 in patients with an abnormal PTFV1 (P = 0.047). This increase in patients with an abnormal PTFV1 was independent from clinical covariates (coefficient B: 0.542, 95% confidence interval 0.057 to 1.027, P = 0.031). Atrial fibrosis was significantly lower with 12.32 ± 1.63% in patients with an abnormal PTFV1 (vs. 20.50 ± 2.09%, P = 0.006), suggesting PTFV1 to be a marker for electrical but not structural remodelling. Conclusions Abnormal PTFV1 is an independent predictor for impaired atrial function and for electrical but not for structural remodelling. PTFV1 may be a promising tool to evaluate patients for atrial cardiomyopathy and for risk of atrial fibrillation