University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

Optimal Allocation of Surgery Blocks to Operating Rooms Under Uncertainty

Abstract: The allocation of surgeries to operating rooms (ORs) is a challenging combinatorial optimization problem. There is also significant uncertainty in the duration of surgical procedures, which further complicates assignment decisions. In this paper, we present stochastic optimization models for the assignment of surgeries to ORs on a given day of surgery. The objective includes a fixed cost of opening ORs and a variable cost of overtime relative to a fixed length-of-day. We describe two types of models. The first is a two-stage stochastic linear program with binary decisions in the first stage and simple recourse in the second stage. The second is its robust counterpart, in which the objective is to minimize the maximum cost associated with an uncertainty set for surgery durations. We describe the mathematical models, bounds on the optimal solution, and solution methodologies, including an easy-to-implement heuristic. Numerical experiments based on real data from a large health-care provider are used to contrast the results for the two models and illustrate the potential for impact in practice. Based on our numerical experimentation, we find that a fast and easy-to-implement heuristic works fairly well, on average, across many instances. We also find that the robust method performs approximately as well as the heuristic, is much faster than solving the stochastic recourse model, and has the benefit of limiting the worst-case outcome of the recourse problem.

Evaluation of 11 terrestrial carbon–nitrogen cycle models against observations from two temperate Free‐Air CO2 Enrichment studies

Abstract: We analysed the responses of 11 ecosystem models to elevated atmospheric [CO2] (eCO(2)) at two temperate forest ecosystems (Duke and Oak Ridge National Laboratory (ORNL) Free-Air CO2 Enrichment (FACE) experiments) to test alternative representations of carbon (C)-nitrogen (N) cycle processes. We decomposed the model responses into component processes affecting the response to eCO(2) and confronted these with observations from the FACE experiments. Most of the models reproduced the observed initial enhancement of net primary production (NPP) at both sites, but none was able to simulate both the sustained 10-yr enhancement at Duke and the declining response at ORNL: models generally showed signs of progressive N limitation as a result of lower than observed plant N uptake. Nonetheless, many models showed qualitative agreement with observed component processes. The results suggest that improved representation of above-ground-below-ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO(2) effects. Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C-N budgets. The two FACE experiments are insufficient to fully constrain terrestrial responses to eCO(2), given the complexity of factors leading to the observed diverging trends, and the consequential inability of the models to explain these trends. Nevertheless, the ecosystem models were able to capture important features of the experiments, lending some support to their projections. (Less)

Clinical Significance of Magnetic Resonance Imaging Markers of Vascular Brain Injury: A Systematic Review and Meta-analysis.

Abstract: Importance Covert vascular brain injury (VBI) is highly prevalent in community-dwelling older persons, but its clinical and therapeutic implications are debated. Objective To better understand the clinical significance of VBI to optimize prevention strategies for the most common age-related neurological diseases, stroke and dementia. Data Source We searched for articles in PubMed between 1966 and December 22, 2017, studying the association of 4 magnetic resonance imaging (MRI) markers of covert VBI (white matter hyperintensities [WMHs] of presumed vascular origin, MRI-defined covert brain infarcts [BIs], cerebral microbleeds [CMBs], and perivascular spaces [PVSs]) with incident stroke, dementia, or death. Study Selection Data were taken from prospective, longitudinal cohort studies including 50 or more adults. Data Extraction and Synthesis We performed inverse variance–weighted meta-analyses with random effects andzscore–based meta-analyses for WMH burden. The significance threshold wasP Main Outcomes and Measures Stroke (hemorrhagic and ischemic), dementia (all and Alzheimer disease), and death. Results Of 2846 articles identified, 94 studies were eligible, with up to 14 529 participants for WMH, 16 012 participants for BI, 15 693 participants for CMB, and 4587 participants for PVS. Extensive WMH burden was associated with higher risk of incident stroke (hazard ratio [HR], 2.45; 95% CI, 1.93-3.12;P Conclusions and Relevance We report evidence that MRI markers of VBI have major clinical significance. This research prompts careful evaluation of the benefit–risk ratio for available prevention strategies in individuals with covert VBI.

Bi-allelic inactivation of TCF1 in hepatic adenomas

Abstract: Liver adenomas are benign tumors at risk of malignant transformation. In a genome-wide search for loss of heterozygosity (LOH) associated with liver adenomas, we found a deletion in chromosome 12q in five of ten adenomas. In most cases, LOH at 12q was the only recurrent genetic alteration observed, suggesting the presence of a tumor-suppressor gene in that region. A minimal common region of deletion was defined in 12q24 that included the gene TCF1 (transcription factor 1), encoding hepatocyte nuclear factor 1 (HNF1; refs 1,2). Heterozygous germline mutations of TCF1 have been identified in individuals affected with maturity-onset diabetes of the young type 3 (MODY3; ref. 3). Bi-allelic inactivation of TCF1 was found in 10 of 16 screened adenomas, and heterozygous germline mutation were present in three affected individuals. Furthermore, 2 well-differentiated hepatocellular carcinomas (HCCs) occurring in normal liver contained somatic bi-allelic mutations of 30 screened HCCs. These results indicate that inactivation of TCF1, whether sporadic or associated with MODY3, is an important genetic event in the occurrence of human liver adenoma, and may be an early step in the development of some HCCs.