Opportunities and challenges with new railway planning approach in Sweden

Long lead times in railway planning can give rise to a significant discrepancy between the original plan and the traffic eventually operated, resulting in inefficient utilization of capacity. Research shows that the railway sector in Sweden would benefit from a different planning approach in which capacity consuming decisions are pushed forward in time whenever possible. This approach is currently being implemented at Trafikverket, the Swedish Transport Administration. With it follows a number of mathematical opportunities and challenges, some of which will be presented in this paper

On the delivery robustness of train timetables with respect to production replanning possibilities

Measuring timetable robustness is a complex task. Previous efforts have mainly been focused on simulation studies or measurements of time supplements. However, these measurements don't capture the production flexibility of a timetable, which is essential for measuring the robustness with regard to the trains' commercial activity commitments, and also for merging the goals of robustness and efficiency. In this article we differentiate between production timetables and delivery timetables. A production timetable contains all stops, meetings and switch crossings, while a delivery timetable only contains stops for commercial activities. If a production timetable is constructed such that it can easily be replanned to cope with delays without breaking any commercial activity commitments it provides delivery robustness without compromising travel efficiency. Changing meeting locations is one of the replanning tools available during operation, and this paper presents a new framework for heuristically optimising a given production timetable with regard to the number of alternative meeting locations. Mixed integer programming is used to find two delivery feasible production solutions, one early and one late. The area between the two solutions represents alternative meeting locations and therefore also the replanning enabled robustness. A case study from Sweden demonstrates how the method can be used to develop better production timetables

The Maraca: a tool for minimizing resource conflicts in a non-periodic railway timetable

While mathematical optimization and operations research receive growing attention in the railway sector, computerized timetabling tools that actually make significant use of optimization remain relatively rare. SICS has developed a prototype tool for non-periodic timetabling that minimizes resource conflicts, enabling the user to focus on the strategic decisions. The prototype is called the Maraca and has been used and evaluated during the railway timetabling construction phase at the Swedish Transport Administration between April and September 2010

Knee arthroscopies: who gets them, what does the radiologist report, and what does the surgeon find?

Background and purpose - Several randomized controlled trials have not shown any added benefit of arthroscopy over placebo surgery or physiotherapy in middle-aged patients with knee symptoms without trauma. We studied the characteristics of the knee arthroscopies performed in southern Sweden. Patients and methods - From the orthopedic surgical records from 2007-2009 in the Skåne region of Sweden (with a population of 1.2 million), we retrieved ICD-10 diagnostic codes and selected all 4,096 arthroscopies that were diagnosed peroperatively with code M23.2 (derangement of meniscus due to old tear or injury) or code M17 (knee osteoarthritis). We extracted information on cartilage and meniscus status at arthroscopy, and we also randomly sampled 502 of these patients from the regional archive of radiology and analyzed the preoperative prevalence of radiographic or magnetic resonance imaging (MRI)-defined osteoarthritis. Results - 2,165 (53%) of the 4,096 arthroscopies had the diagnostic code M23.2 or M17. In this subgroup, 1,375 cases (64%) had typical findings consistent with degenerative meniscal tear (i.e. that correspond to a degenerative meniscal tear in at least a third of all arthroscopies). Of the randomly sampled patients, the preoperative prevalence of radiological knee osteoarthritis was 46%. Interpretation - There is a discrepancy between evidence-based medicine treatment guidelines and clinical practice regarding the amount of knee arthroscopies performed in patients with symptoms of degenerative knee disease

Persistent sleep problems among people in recovery from substance use disorders: a mixed methods study

Background The aims of this study are to examine the one-year trajectory of sleep problems, identify clinical correlates, and describe subjective experiences related to persistent sleep problems during recovery from substance use disorders (SUD). Methods This study builds on a sequential mixed method design. The quantitative component features data from a prospective longitudinal study of 127 poly-SUD patients in the Stavanger area in Norway, while the qualitative component describes a thematic analysis of interviews with 16 persons from this study still experiencing sleep problems after at least one year of abstinence. Results The prevalence of sleep problems at baseline for the whole cohort was 79%. Among the 59 patients who were abstinent after one year, N = 20 (33.9%) had moderate and N = 11 (18.6%) had severe sleep problems. Persistent sleep problems were associated with psychological distress and were experienced as a major challenge in the struggle to stay drug free. Establishing daily routines related to work, school, and care for children were coping strategies for participants with persistent sleep problems. Conclusions Persistent sleep problems are often overlooked in a clinical setting. Based on our findings, these issues pose a major challenge in the struggle to stay drug free. For patients with psychological distress, and lack of responsibilities that established daily routines, sleep difficulties may result in increased risk of drug use episodes that result in relapse. These results argue that screening and evidence-based methods for insomnia and sleep health-programs should be commonplace adjunct intervention for patients with SUDs.publishedVersio

Mapping the ultrafast flow of harvested solar energy in living photosynthetic cells

Photosynthesis transfers energy efficiently through a series of antenna complexes to the reaction center where charge separation occurs. Energy transfer in vivo is primarily monitored by measuring fluorescence signals from the small fraction of excitations that fail to result in charge separation. Here, we use two-dimensional electronic spectroscopy to follow the entire energy transfer process in a thriving culture of the purple bacteria, Rhodobacter sphaeroides. By removing contributions from scattered light, we extract the dynamics of energy transfer through the dense network of antenna complexes and into the reaction center. Simulations demonstrate that these dynamics constrain the membrane organization into small pools of core antenna complexes that rapidly trap energy absorbed by surrounding peripheral antenna complexes. The rapid trapping and limited back transfer of these excitations lead to transfer efficiencies of 83% and a small functional light-harvesting unit

Current and future impact of osteoarthritis on health care: a population-based study with projections to year 2032.

To estimate the current and future (to year 2032) impact of osteoarthritis (OA) health care seeking

Positive solutions of Schr\"odinger equations and fine regularity of boundary points

Given a Lipschitz domain $\Omega$ in ${\mathbb R} ^N$ and a nonnegative potential $V$ in $\Omega$ such that $V(x)\, d(x,\partial \Omega)^2$ is bounded in $\Omega$ we study the fine regularity of boundary points with respect to the Schr\"odinger operator $L_V:= \Delta -V$ in $\Omega$. Using potential theoretic methods, several conditions equivalent to the fine regularity of $z \in \partial \Omega$ are established. The main result is a simple (explicit if $\Omega$ is smooth) necessary and sufficient condition involving the size of $V$ for $z$ to be finely regular. An essential intermediate result consists in a majorization of $\int_A | {\frac {u} {d(.,\partial \Omega)}} | ^2\, dx$ for $u$ positive harmonic in $\Omega$ and $A \subset \Omega$. Conditions for almost everywhere regularity in a subset $A$ of $\partial \Omega$ are also given as well as an extension of the main results to a notion of fine ${\mathcal L}_1 | {\mathcal L}_0$-regularity, if ${\mathcal L}_j={\mathcal L}-V_j$, $V_0,\, V_1$ being two potentials, with $V_0 \leq V_1$ and ${\mathcal L}$ a second order elliptic operator.Comment: version 1. 23 pages version 3. 28 pages. Mainly a typo in Theorem 1.1 is correcte

Extrapolation of the Dirichlet problem for elliptic equations with complex coefficients

In this paper, we prove an extrapolation result for complex coefficient divergence form operators that satisfy a strong ellipticity condition known as $p$-{\it ellipticity}. Specifically, let $\Omega$ be a chord-arc domain in $\mathbb R^n$ and the operator $\mathcal L = \partial_{i}\left(A_{ij}(x)\partial_{j}\right) +B_{i}(x)\partial_{i}$ be elliptic, with $|B_i(x)| \le K\delta(x)^{-1}$ for a small $K$. Let p_0 = \sup\{p>1: A \,\,\text{is}\,\, \text{p-elliptic}\}. We establish that if the $L^q$ Dirichlet problem is solvable for $\mathcal L$ for some $1<q< \frac{p_0(n-1)}{(n-2)}$, then the $L^p$ Dirichlet problem is solvable for all $p$ in the range $[q, \frac{p_0(n-1)}{(n-2)})$. In particular, if the matrix $A$ is real, or $n=2$, the $L^p$ Dirichlet problem is solvable for $p$ in the range $[q, \infty)$.Comment: 16 pages. To appear in JF