
Swiss National Science Foundation
governmentBern, Bern, Switzerland
Research output, citation impact, and the most-cited recent papers from Swiss National Science Foundation (Switzerland). Aggregated across the NobleBlocks index of 300M+ scholarly works.
Top-cited papers from Swiss National Science Foundation
An estimated 80,000 anterior cruciate ligament (ACL) tears occur annually in the United States. The highest incidence is in individuals 15 to 25 years old who participate in pivoting sports. With an estimated cost for these injuries of almost a billion dollars per year, the ability to identify risk factors and develop prevention strategies has widespread health and fiscal importance. Seventy percent of ACL injuries occur in noncontact situations. The risk factors for non-contact ACL injuries fall into four distinct categories: environmental, anatomic, hormonal, and biomechanical. Early data on existing neuromuscular training programs suggest that enhancing body control may decrease ACL injuries in women. Further investigation is needed prior to instituting prevention programs related to the other risk factors.
This article investigates a computationally simple variant of boosting, L2Boost, which is constructed from a functional gradient descent algorithm with the L2-loss function. Like other boosting algorithms, L2Boost uses many times in an iterative fashion a prechosen fitting method, called the learner. Based on the explicit expression of refitting of residuals of L2Boost, the case with (symmetric) linear learners is studied in detail in both regression and classification. In particular, with the boosting iteration m working as the smoothing or regularization parameter, a new exponential bias-variance trade-off is found with the variance (complexity) term increasing very slowly as m tends to infinity. When the learner is a smoothing spline, an optimal rate of convergence result holds for both regression and classification and the boosted smoothing spline even adapts to higher-order, unknown smoothness. Moreover, a simple expansion of a (smoothed) 0–1 loss function is derived to reveal the importance of the decision boundary, bias reduction, and impossibility of an additive bias-variance decomposition in classification. Finally, simulation and real dataset results are obtained to demonstrate the attractiveness of L2Boost. In particular, we demonstrate that L2Boosting with a novel component-wise cubic smoothing spline is both practical and effective in the presence of high-dimensional predictors.
The Samuel Lunenfeld Research Institute and the Department of Surgery, Mount Sinai Hospital and the University of Toronto Liver Transplantation Program, University of Toronto, Toronto, Ontario, Canada
This article shows that identical offers in an ultimatum game generate systematically different rejection rates depending on the other offers that are available to the proposer. This result casts doubt on the consequentialist practice in economics to define the utility of an action solely in terms of the consequences of the action irrespective of the set of alternatives. It means in particular that negatively reciprocal behavior cannot be fully captured by equity models that are exclusively based on preferences over the distribution of material payoffs.
As breaking news unfolds people increasingly rely on social media to stay abreast of the latest updates. The use of social media in such situations comes with the caveat that new information being released piecemeal may encourage rumours, many of which remain unverified long after their point of release. Little is known, however, about the dynamics of the life cycle of a social media rumour. In this paper we present a methodology that has enabled us to collect, identify and annotate a dataset of 330 rumour threads (4,842 tweets) associated with 9 newsworthy events. We analyse this dataset to understand how users spread, support, or deny rumours that are later proven true or false, by distinguishing two levels of status in a rumour life cycle i.e., before and after its veracity status is resolved. The identification of rumours associated with each event, as well as the tweet that resolved each rumour as true or false, was performed by journalist members of the research team who tracked the events in real time. Our study shows that rumours that are ultimately proven true tend to be resolved faster than those that turn out to be false. Whilst one can readily see users denying rumours once they have been debunked, users appear to be less capable of distinguishing true from false rumours when their veracity remains in question. In fact, we show that the prevalent tendency for users is to support every unverified rumour. We also analyse the role of different types of users, finding that highly reputable users such as news organisations endeavour to post well-grounded statements, which appear to be certain and accompanied by evidence. Nevertheless, these often prove to be unverified pieces of information that give rise to false rumours. Our study reinforces the need for developing robust machine learning techniques that can provide assistance in real time for assessing the veracity of rumours. The findings of our study provide useful insights for achieving this aim.
Leading scholars and publishers from ten countries have agreed a definition of predatory publishing that can protect scholarship. It took 12 hours of discussion, 18 questions and 3 rounds to reach. Leading scholars and publishers from ten countries have agreed a definition of predatory publishing that can protect scholarship. It took 12 hours of discussion, 18 questions and 3 rounds to reach.
PREVIOUS studies in this laboratory have shown that the concentration of copper in serum is considerably increased after acute myocardial infarction.1 This change is proportional to an increase in ceruloplasmin, the copper protein of human serum, and its capacity to oxidize paraphenylenediamine.2 In the pursuit of these studies, the concentration of zinc and the activity of zinc enzymes in human serum have been found to be altered markedly in myocardial necrosis.Lactic dehydrogenase has recently been shown to be a zinc enzyme,3 and malic dehydrogenase also appears to be a metalloenzyme.4 These enzymes require coenzyme 1 (diphosphopyridine nucleotide) for their . . .
OBJECTIVE: To test whether complications happen more often with the internal jugular or the subclavian central venous approach. DATA SOURCE: Systematic search (MEDLINE, Cochrane Library, EMBASE, bibliographies) up to June 30, 2000, with no language restriction. STUDY SELECTION: Reports on prospective comparisons of internal jugular vs. subclavian catheter insertion, with dichotomous data on complications. DATA EXTRACTION: No valid randomized trials were found. Seventeen prospective comparative trials with data on 2,085 jugular and 2,428 subclavian catheters were analyzed. Meta-analyses were performed with relative risk (RR) and 95% confidence interval (CI), using fixed and random effects models. DATA SYNTHESIS: In six trials (2,010 catheters), there were significantly more arterial punctures with jugular catheters compared with subclavian (3.0% vs. 0.5%, RR 4.70 [95% CI, 2.05-10.77]). In six trials (1,299 catheters), there were significantly less malpositions with the jugular access (5.3% vs. 9.3%, RR 0.66 [0.44-0.99]). In three trials (707 catheters), the incidence of bloodstream infection was 8.6% with the jugular access and 4.0% with the subclavian access (RR 2.24 [0.62-8.09]). In ten trials (3,420 catheters), the incidence of hemato- or pneumothorax was 1.3% vs. 1.5% (RR 0.76 [0.43--1.33]). In four trials (899), the incidence of vessel occlusion was 0% vs. 1.2% (RR 0.29 [0.07-1.33]). CONCLUSIONS: There are more arterial punctures but less catheter malpositions with the internal jugular compared with the subclavian access. There is no evidence of any difference in the incidence of hemato- or pneumothorax and vessel occlusion. Data on bloodstream infection are scarce. These data are from nonrandomized studies; selection bias cannot be ruled out. In terms of risk, the data most likely represent a best case scenario. For rational decision-making, randomized trials are needed.
Comprehensive geriatric assessment is a technique for multidimensional diagnosis of frail elderly people with the purpose of planning and/or delivering medical, psychosocial, and rehabilitative care. When comprehensive geriatric assessment is coupled with some therapy, then the term geriatric evaluation and management (GEM) will be used. Following a brief history of comprehensive geriatric assessment, we describe the varied patterns of GEM program organization and review the literature of studies examining GEM effectiveness. Program diversity complicates drawing firm conclusions about GEM effects; however, the vast majority of studies report positive, if not uniformly significant, results. Our analysis suggests that much of the variability in findings is due to sample size limitations. In order to reach conclusions of program effects across studies and to avoid problems of small sample sizes, we undertook a formal meta-analysis. In this initial meta-analysis, we sought to evaluate the effect of GEM programs on a single outcome: mortality. We pooled all published GEM controlled trials into four major groups: inpatient consultation services, inpatient GEM units, home assessment services, and outpatient GEM programs. Meta-analysis of 6-month mortality demonstrates a 39% reduction of mortality for inpatient consultation services (odds ratio 0.61, 95% confidence interval 0.46-0.81, P = 0.0008) and a 37% reduction of mortality for inpatient GEM units (odds ratio 0.63, 95% CI 0.42-0.93, P = 0.02). Home assessment services reduced mortality by 29% (odds ratio 0.71, 95% CI 0.55-0.90, P = 0.005). On the other hand, no significant survival effect was found for outpatient GEM programs (odds ratio 0.96, 95% confidence interval 0.61-1.49).(ABSTRACT TRUNCATED AT 250 WORDS)
Euclidean distance matrices (EDMs) are matrices of the squared distances between points. The definition is deceivingly simple; thanks to their many useful properties, they have found applications in psychometrics, crystallography, machine learning, wireless sensor networks, acoustics, and more. Despite the usefulness of EDMs, they seem to be insufficiently known in the signal processing community. Our goal is to rectify this mishap in a concise tutorial. We review the fundamental properties of EDMs, such as rank or (non)definiteness, and show how the various EDM properties can be used to design algorithms for completing and denoising distance data. Along the way, we demonstrate applications to microphone position calibration, ultrasound tomography, room reconstruction from echoes, and phase retrieval. By spelling out the essential algorithms, we hope to fast-track the readers in applying EDMs to their own problems. The code for all of the described algorithms and to generate the figures in the article is available online at http://lcav.epfl.ch/ivan.dokmanic. Finally, we suggest directions for further research.
We aimed to determine the frequency and time course of the enlargement of ischemic cerebral lesions following human stroke and to study the effect of the state of perfusion on lesion enlargement. Acute lesion volumes were measured on diffusion-weighted magnetic resonance images and compared with lesion volumes measured on T2-weighted images at 7 days or later. Forty-four measurements were performed between 2 and 53 hours after stroke onset in 28 patients. Thirteen patients also had magnetic resonance perfusion imaging performed. In 12 (43%) of 28 patients the initial lesion volume increased by 20% or more. The number of studies showing enlargement of the ischemic lesion volume ranged from 12 (43%) of 28 at or after 2 hours to 10 (38%) of 26 at or after 6 hours, 5 (33%) of 15 at or after 24 hours, and 2 (33%) of 6 at or after 48 hours. In 7 of the 10 patients in whom the hypoperfusion volume acutely exceeded the volume of the abnormality on diffusion-weighted images, lesion volume increased by 20% or more. This study provided evidence that substantial enlargement of human cerebral ischemic lesion volumes can occur beyond the first 6, 12, or 24 hours after onset. A mismatch acutely between the region of hypoperfusion (larger) and the region of diffusion abnormality (smaller) may be predictive of ischemic lesion enlargement.
Serum concentrations of immunoreactive tumor necrosis factor/cachectin (TNF), interleukin-1 beta (IL-1 beta), interferon-gamma (IFN gamma), and interferon-alpha (IFN alpha) were prospectively measured in 70 patients with septic shock to determine their evolution and prognostic values. In a univariate analysis, levels of TNF (P = .002) and IL-1 beta (P = .05) were associated with the patient's outcome, but not IFN alpha (P = .15) and IFN gamma (P = .26). In contrast, in a stepwise logistic regression analysis, the severity of the underlying disease (P = .01), the age of the patient (P = .02), the documentation of infection (nonbacteremic infections vs. bacteremias, P = .03), the urine output (P = .04), and the arterial pH (P = .05) contributed more significantly to prediction of patient outcome than the serum levels of TNF (P = .07). After 10 days, the median concentration of TNF was undetectable (less than 100 pg/ml) in the survivors, whereas it remained elevated (305 pg/ml, P = .002) in the nonsurvivors. Thus, in patients with septic shock due to various gram-negative bacteria, other parameters than the absolute serum concentration of immunoreactive TNF contributed significantly to the prediction of outcome.
The topic of this paper is inference in models in which parameters are defined by moment inequalities and/or equalities. The parameters may or may not be identified. This paper introduces a new class of confidence sets and tests based on generalized moment selection (GMS). GMS procedures are shown to have correct asymptotic size in a uniform sense and are shown not to be asymptotically conservative. The power of GMS tests is compared to that of subsampling, m out of n bootstrap, and “plug-in asymptotic” (PA) tests. The latter three procedures are the only general procedures in the literature that have been shown to have correct asymptotic size (in a uniform sense) for the moment inequality/equality model. GMS tests are shown to have asymptotic power that dominates that of subsampling, m out of n bootstrap, and PA tests. Subsampling and m out of n bootstrap tests are shown to have asymptotic power that dominates that of PA tests.
ABSTRACT This article, which forms the introduction to a collection of studies, focuses on processes of state construction and deconstruction in contemporary Africa. Its objective is to better understand how local, national and transnational actors forge and remake the state through processes of negotiation, contestation and bricolage. Following a critique of the predominant state failure literature and its normative and analytical shortcomings, the authors identify four key arguments of the scholarly literature on the state in Africa, which concern the historicity of the state in Africa, the embeddedness of bureaucratic organizations in society, the symbolic and material dimensions of statehood and the importance of legitimacy. A heuristic framework entitled ‘negotiating statehood’ is proposed, referring to the dynamic and partly undetermined processes of state formation and failure by a multitude of social actors who compete over the institutionalization of power relations. The article then operationalizes this framework in three sections that partly conceptualize, partly illustrate who negotiates statehood in contemporary Africa (actors, resources and repertoires); where these negotiation processes occur (negotiation arenas and tables); and what these processes are all about (objects of negotiation). Empirical examples drawn from a variety of political contexts across the African continent illustrate these propositions.
OBJECTIVES: To analyze the effect of tight glycemic control with the use of intensive insulin therapy on cerebral glucose metabolism in patients with severe brain injury. DESIGN: Retrospective analysis of a prospective observational cohort. SETTING: University hospital neurologic intensive care unit. PATIENTS: Twenty patients (median age 59 yrs) monitored with cerebral microdialysis as part of their clinical care. INTERVENTIONS: Intensive insulin therapy (systemic glucose target: 4.4-6.7 mmol/L [80-120 mg/dL]). MEASUREMENTS AND MAIN RESULTS: Brain tissue markers of glucose metabolism (cerebral microdialysis glucose and lactate/pyruvate ratio) and systemic glucose were collected hourly. Systemic glucose levels were categorized as within the target "tight" (4.4-6.7 mmol/L [80-120 mg/dL]) vs. "intermediate" (6.8-10.0 mmol/L [121-180 mg/dL]) range. Brain energy crisis was defined as a cerebral microdialysis glucose <0.7 mmol/L with a lactate/pyruvate ratio >40. We analyzed 2131 cerebral microdialysis samples: tight systemic glucose levels were associated with a greater prevalence of low cerebral microdialysis glucose (65% vs. 36%, p < 0.01) and brain energy crisis (25% vs.17%, p < 0.01) than intermediate levels. Using multivariable analysis, and adjusting for intracranial pressure and cerebral perfusion pressure, systemic glucose concentration (adjusted odds ratio 1.23, 95% confidence interval [CI] 1.10-1.37, for each 1 mmol/L decrease, p < 0.001) and insulin dose (adjusted odds ratio 1.10, 95% CI 1.04-1.17, for each 1 U/hr increase, p = 0.02) independently predicted brain energy crisis. Cerebral microdialysis glucose was lower in nonsurvivors than in survivors (0.46 +/- 0.23 vs. 1.04 +/- 0.56 mmol/L, p < 0.05). Brain energy crisis was associated with increased mortality at hospital discharge (adjusted odds ratio 7.36, 95% CI 1.37-39.51, p = 0.02). CONCLUSIONS: In patients with severe brain injury, tight systemic glucose control is associated with reduced cerebral extracellular glucose availability and increased prevalence of brain energy crisis, which in turn correlates with increased mortality. Intensive insulin therapy may impair cerebral glucose metabolism after severe brain injury.
It has long been recognized that there is considerable heterogeneity in individual risk taking behavior, but little is known about the distribution of risk taking types. We present a parsimonious characterization of risk taking behavior by estimating a finite mixture model for three different experimental data sets, two Swiss and one Chinese, over a large number of real gains and losses. We find two major types of individuals: In all three data sets, the choices of roughly 80% of the subjects exhibit significant deviations from linear probability weighting of varying strength, consistent with prospect theory. Twenty percent of the subjects weight probabilities near linearly and behave essentially as expected value maximizers. Moreover, individuals are cleanly assigned to one type with probabilities close to unity. The reliability and robustness of our classification suggest using a mix of preference theories in applied economic modeling.
CERN-LHC. Experimental measurements of Elliptic Flow, v2(pT), as a function of pT for eight 10% centrality intervals (from 0-10% most central to 70-80% most peripheral), for pT from 0.5 to 20 GeV, and for three ranges in pseudorapidity (|eta| < 1, 1 < |eta| < 2 and 2 < |eta| < 2.5) (Tables 1-24). In addition, data points of pseudorapidity dependence of elliptic flow, v2(eta), in five pT intervals and eight 10% centrality intervals are presented (Tables 25-64). The elliptic flow parameter (v2) is measured as the second harmonic of the Fourier analysis of the azimuthal angle distribution relative to the azimuthal angle of the reaction plane. For more details see the paper.
Media is full of false claims. Even Oxford Dictionaries named "post-truth" as the word of 2016. This makes it more important than ever to build systems that can identify the veracity of a story, and the nature of the discourse around it. Ru-mourEval is a SemEval shared task that aims to identify and handle rumours and reactions to them, in text. We present an annotation scheme, a large dataset covering multiple topics -each having their own families of claims and replies -and use these to pose two concrete challenges as well as the results achieved by participants on these challenges.
Donation after circulatory death (DCD) has become an accepted practice in many countries and remains a focus of intense interest in the transplant community. The present study is aimed at providing a description of the current situation of DCD in European countries. Specific questionnaires were developed to compile information on DCD practices, activities and post-transplant outcomes. Thirty-five countries completed the survey. DCD is practiced in 18 countries: eight have both controlled DCD (cDCD) and uncontrolled DCD (uDCD) programs, 4 only cDCD and 6 only uDCD. All these countries have legally binding and/or nonbinding texts to regulate the practice of DCD. The no-touch period ranges from 5 to 30 min. There are variations in ante and post mortem interventions used for the practice of cDCD. During 2008-2016, the highest DCD activity was described in the United Kingdom, Spain, Russia, the Netherlands, Belgium and France. Data on post-transplant outcomes of patients who receive DCD donor kidneys show better results with grafts obtained from cDCD versus uDCD donors. In conclusion, DCD is becoming increasingly accepted and performed in Europe, importantly contributing to the number of organs available and providing acceptable post-transplantation outcomes.
Revision hip arthroplasty in patients with massive acetabular bone deficiency has generally given poor long-term results. We report the use of an 'anti-protrusio cage', secured to the ischium and ilium, which bridges areas of acetabular bone loss, provides support for the acetabular socket, and allows pelvic bone grafting in an environment protected from excessive stress. Forty-two failed hip arthroplasties with massive acetabular bone loss were revised with the Burch-Schneider anti-protrusio cage and evaluated after two to 11 years (mean five years). There was failure due to sepsis in five hips (12%) and aseptic loosening in five (12%); the remaining 32 hips (76%) showed no evidence of acetabular component failure or loosening.