Advanced Multilevel Node Separator Algorithms

A node separator of a graph is a subset S of the nodes such that removing S and its incident edges divides the graph into two disconnected components of about equal size. In this work, we introduce novel algorithms to find small node separators in large graphs. With focus on solution quality, we introduce novel flow-based local search algorithms which are integrated in a multilevel framework. In addition, we transfer techniques successfully used in the graph partitioning field. This includes the usage of edge ratings tailored to our problem to guide the graph coarsening algorithm as well as highly localized local search and iterated multilevel cycles to improve solution quality even further. Experiments indicate that flow-based local search algorithms on its own in a multilevel framework are already highly competitive in terms of separator quality. Adding additional local search algorithms further improves solution quality. Our strongest configuration almost always outperforms competing systems while on average computing 10% and 62% smaller separators than Metis and Scotch, respectively

Recent Advances in Graph Partitioning

We survey recent trends in practical algorithms for balanced graph partitioning together with applications and future research directions

Physicians Report Barriers to Deliver Best Practice Care for Asplenic Patients: A Cross-Sectional Survey

Background: Current management of asplenic patients is not in compliance with best practice standards, such as defined by the British Committee for Standards in Haematology. To improve quality of care, factors inhibiting best practice care delivery need to be identified first. With this study, we aimed to identify and quantify physicians' barriers to adhere to best practice management of asplenic patients in the Netherlands. Methods and Principal Findings: A cross-sectional survey, preceded by multiple focus group discussions, was performed among Dutch physicians responsible for prevention of infections in asplenic patients, including specialists ( of Internal medicine and Surgery) and general practitioners (GPs). Forty seven GPs and seventy three hospital specialists returned the questionnaire, yielding response rates of 47% and 36,5% respectively. Physicians reported several barriers to deliver best practice. For both GPs and specialists, the most frequently listed barriers were: poor patient knowledge (> 80% of hospital specialists and GPs) and lack of clarity about which physician is responsible for the management of asplenic patients (50% of Internists, 46% of Surgeons, 55% of GPs). Both GPs and hospital specialists expressed to experience a lack of mutual trust: specialists were uncertain whether the GP would follow their advice given on patient discharge (33-59%), whereas half of GPs was not convinced that specialists' discharge letters contained the correct recommendations. Almost all physicians (> 90%) indicated that availability of a national guideline would improve adherence to best practice, especially if accessible online. Conclusion: This study showed that, in accordance with reports on international performance, care delivery for asplenic patients in the Netherlands is suboptimal. We identified and quantified perceived barriers by physicians that prevent adherence to post-splenectomy guidelines for the first time. Better transmural collaboration and better informed patients are likely to improve the quality of care of the asplenic patient population. A national, online-available guideline is urgently require

Nutrition, diet and immunosenescence

Ageing is characterized by immunosenescence and the progressive decline in immunity in association with an increased frequency of infections and chronic disease. This complex process affects both the innate and adaptive immune systems with a progressive decline in most immune cell populations and defects in activation resulting in loss of function. Although host genetics and environmental factors, such as stress, exercise and diet can impact on the onset or course of immunosenescence, the mechanisms involved are largely unknown. This review focusses on identifying the most significant aspects of immunosenescence and on the evidence that nutritional intervention might delay this process, and consequently improve the quality of life of the elderly

Serum neurofilament dynamics predicts neurodegeneration and clinical progression in presymptomatic Alzheimer's disease

Neurofilament light chain (NfL) is a promising fluid biomarker of disease progression for various cerebral proteopathies. Here we leverage the unique characteristics of the Dominantly Inherited Alzheimer Network and ultrasensitive immunoassay technology to demonstrate that NfL levels in the cerebrospinal fluid (n = 187) and serum (n = 405) are correlated with one another and are elevated at the presymptomatic stages of familial Alzheimer's disease. Longitudinal, within-person analysis of serum NfL dynamics (n = 196) confirmed this elevation and further revealed that the rate of change of serum NfL could discriminate mutation carriers from non-mutation carriers almost a decade earlier than cross-sectional absolute NfL levels (that is, 16.2 versus 6.8 years before the estimated symptom onset). Serum NfL rate of change peaked in participants converting from the presymptomatic to the symptomatic stage and was associated with cortical thinning assessed by magnetic resonance imaging, but less so with amyloid-β deposition or glucose metabolism (assessed by positron emission tomography). Serum NfL was predictive for both the rate of cortical thinning and cognitive changes assessed by the Mini-Mental State Examination and Logical Memory test. Thus, NfL dynamics in serum predict disease progression and brain neurodegeneration at the early presymptomatic stages of familial Alzheimer's disease, which supports its potential utility as a clinically useful biomarker

The ratio of horizontal to vertical displacement in solar oscillations estimated from combined SO/PHI and SDO/HMI observations

In order to make accurate inferences about the solar interior using helioseismology, it is essential to understand all the relevant physical effects on the observations. One effect to understand is the (complex-valued) ratio of the horizontal to vertical displacement of the p- and f-modes at the height at which they are observed. Unfortunately, it is impossible to measure this ratio directly from a single vantage point, and it has been difficult to disentangle observationally from other effects. In this paper we attempt to measure the ratio directly using 7.5 hours of simultaneous observations from the Polarimetric and Helioseismic Imager on board Solar Orbiter and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. While image geometry problems make it difficult to determine the exact ratio, it appears to agree well with that expected from adiabatic oscillations in a standard solar model. On the other hand it does not agree with a commonly used approximation, indicating that this approximation should not be used in helioseismic analyses. In addition, the ratio appears to be real-valued.Comment: Accepted for publication in Astronomy & Astrophysics. 8 pages, 8 figure

Intensity contrast of solar network and faculae close to the solar limb, observed from two vantage points

The brightness of faculae and network depends on the angle at which they are observed and the magnetic flux density. Close to the limb, assessment of this relationship has until now been hindered by the increasingly lower signal in magnetograms. This preliminary study aims at highlighting the potential of using simultaneous observations from different vantage points to better determine the properties of faculae close to the limb. We use data from the Solar Orbiter/Polarimetric and Helioseismic Imager (SO/PHI), and the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI), recorded at $\sim60^\circ$ angular separation of their lines of sight at the Sun. We use continuum intensity observed close to the limb by SO/PHI and complement it with the co-observed $B_{\rm LOS}$ from SDO/HMI, originating closer to disc centre (as seen by SDO/HMI), thus avoiding the degradation of the magnetic field signal near the limb. We derived the dependence of facular brightness in the continuum on disc position and magnetic flux density from the combined observations of SO/PHI and SDO/HMI. Compared with a single point of view, we were able to obtain contrast values reaching closer to the limb and to lower field strengths. We find the general dependence of the limb distance at which the contrast is maximum on the flux density to be at large in line with single viewpoint observations, in that the higher the flux density is, the closer the turning point lies to the limb. There is a tendency, however, for the maximum to be reached closer to the limb when determined from two vantage points. We note that due to the preliminary nature of this study, these results must be taken with caution. Our analysis shows that studies involving two viewpoints can significantly improve the detection of faculae near the solar limb and the determination of their brightness contrast relative to the quiet Sun

Age-dependent susceptibility to a viral disease due to decreased natural killer cell numbers and trafficking

Age-related defects in natural killer cell numbers and function underlie the decreased resistance to mousepox infection in aging mice

An interdisciplinary guideline development process: the Clinic on Low-back pain in Interdisciplinary Practice (CLIP) low-back pain guidelines

<p>Abstract</p> <p>Background</p> <p>Evaluation of low-back pain guidelines using Appraisal of Guidelines Research and Evaluation (AGREE) criteria has shown weaknesses, particularly in stakeholder involvement and applicability of recommendations. The objectives of this project were to: 1) develop a primary care interdisciplinary clinical practice guideline aimed at preventing prolonged disability from low-back pain, using a community of practice approach, and 2) assess the participants' impressions with the process, and evaluate the relationship between participant characteristics and their participation.</p> <p>Methods</p> <p>Ten stakeholder representatives recruited 136 clinicians to participate in this community of practice. Clinicians were drawn from the following professions: physiotherapists (46%), occupational therapists (37%), and family physicians (17%). Using previously published guidelines, systematic reviews, and meta-analyses, a first draft of the guidelines was presented to the community of practice. Four communication tools were provided for discussion and exchanges with experts: a web-based discussion forum, an anonymous comment form, meetings, and a symposium. Participants were prompted for comments on interpretation, clarity, and applicability of the recommendations. Clinical management recommendations were revised following these exchanges. At the end of the project, a questionnaire was sent to the participants to assess satisfaction towards the guidelines and the development process.</p> <p>Results</p> <p>Twelve clinical management recommendations on management of low-back pain and persistent disability were initially developed. These were discussed through 188 comments posted on the discussion forum and 103 commentary forms submitted. All recommendations were modified following input of the participants. A clinical algorithm summarizing the guidelines was also developed. A response rate of 75% was obtained for the satisfaction questionnaire. The majority of respondents appreciated the development process and agreed with the guideline content. Most participants thought recommendations improved between versions, and that participant comments contributed to this improvement. All stakeholders officially endorsed the guidelines.</p> <p>Conclusion</p> <p>The community of practice approach was a successful method to develop guidelines on low-back pain, with participants providing information to improve guideline recommendations. The information technology infrastructure that was developed remains for continuous interdisciplinary exchanges and updating of the guidelines.</p