107 research outputs found

    The curse of ties in congestion games with limited lookahead

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    We introduce a novel framework to model limited lookahead in congestion games. Intuitively, the players enter the game sequentially and choose an optimal action under the assumption that the k - 1 subsequent players play subgame-perfectly. Our model naturally interpolates between outcomes of greedy best-response (k = 1) and subgame-perfect outcomes (k = n, the number of players). We study the impact of limited lookahead (parameterized by k) on the stability and inefficiency of the resulting outcomes. As our results reveal, increased lookahead does not necessarily lead to better outcomes; in fact, its effect crucially depends on the existence of ties and the type of game under consideration

    Judgment Aggregation under Issue Dependencies

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    We introduce a new family of judgment aggregation rules, called the binomial rules, designed to account for hidden dependencies between some of the issues being judged. To place them within the landscape of judgment aggregation rules, we analyse both their axiomatic properties and their computational complexity, and we show that they contain both the well-known distance-based rule and the basic rule returning the most frequent overall judgment as special cases. To evaluate the performance of our rules empirically, we apply them to a dataset of crowdsourced judgments regarding the quality of hotels extracted from the travel website TripAdvisor. In our experiments we distinguish between the full dataset and a subset of highly polarised judgments, and we develop a new notion of polarisation for profiles of judgments for this purpose, which may also be of independent interest

    Size reconstructibility of graphs

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    The deck of a graph GG is given by the multiset of (unlabelled) subgraphs {Gv:vV(G)}\{G-v:v\in V(G)\}. The subgraphs GvG-v are referred to as the cards of GG. Brown and Fenner recently showed that, for n29n\geq29, the number of edges of a graph GG can be computed from any deck missing 2 cards. We show that, for sufficiently large nn, the number of edges can be computed from any deck missing at most 120n\frac1{20}\sqrt{n} cards.Comment: 15 page

    Impact of blood storage and sample handling on quality of high dimensional flow cytometric data in multicenter clinical research

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    Obtaining reliable and reproducible high quality data in multicenter clinical research settings requires design of optimal standard operating procedures. While the need for standardization in sample processing and data analysis is well-recognized, the impact of sample handling in the pre-analytical phase remains underestimated. We evaluated the impact of sample storage time (approximate to transport time) and temperature, type of anticoagulant, and limited blood volume on reproducibility of flow cytometric studies. EDTA and Na-Heparin samples processed with the EuroFlow bulk lysis protocol, stained and stored at 4 degrees C showed fairly stable expression of cell surface markers and distribution of the major leukocyte populations for up to 72 h. Additional sample fixation (1% PFA, Fix & Perm) did not have any beneficial effects. Blood samples stored for < 24 h at room temperature before processing and staining seemed suitable for reliable immunophenotyping, although losses in absolute cell numbers were observed. The major losses were observed in myeloid cells and monocytes, while lymphocytes seemed less affected. Expression of cell surface markers and population distribution were more stable in Na-Heparin blood than in EDTA blood. However, storage of Na-Heparin samples was associated with faster decrease in leukocyte counts over time. Whole blood fixation strategies (Cyto-Chex, TransFix) improved long-term population distribution, but were detrimental for expression of cellular markers. The main conclusions from this study on healthy donor blood samples were successfully confirmed in EDTA clinical (patient) blood samples with different time delays until processing. Finally, we recognized the need for adjustments in bulk lysis in case of insufficient blood volumes. Despite clear overall conclusions, individual markers and cell populations had different preferred conditions. Therefore, specific guidelines for sample handling should always be adjusted to the clinical application and the main target leukocyte population

    Cardiac Catheterizations in Patients With Prior Coronary Bypass Surgery:Impact of Access Strategy on Short-Term Safety and Long-Term Efficacy Outcomes

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    Little data are available on access strategy outcomes for cardiac catheterizations in patients with prior coronary artery bypass graft surgery (CABG). We investigated the effect of transradial access (TRA) and transfemoral access (TFA) on short-term major vascular complications (MVC) and long-term major adverse cardiovascular events (MACE). In this single-center, retrospective cohort study, 1084 patients met our inclusion criteria (TRA = 469; TFA = 615). The cumulative incidence for the primary safety endpoint MVC at 30 days (a composite of major bleeding, retroperitoneal hematoma, dissection, pseudoaneurysm, and arteriovenous fistula) was lower with TRA (0.7% vs 3.0%, P &lt;.01) and this difference remained significant after propensity score adjustment (odds ratio: 0.24; 95% CI, 0.07-0.83; P =.024). The cumulative incidence for the primary efficacy endpoint MACE at 36 months (a composite of all-cause mortality, myocardial infarction, stroke, and urgent target vessel revascularization) was 28.6% with TRA and 27.6% with TFA, respectively. Kaplan-Meier curves showed no difference for the primary efficacy endpoint (P =.65). Contrast use (mL) was significantly lower with TRA (130 [100-180] vs 150 [100-213], P &lt;.01). In conclusion, in patients with prior CABG, TRA was associated with significantly fewer short-term MVC and contrast use, but not with a difference in long-term MACE, compared with TFA.</p

    Association of vessel fractional flow reserve (vFFR) with luminal obstruction and plaque characteristics as detected by optical coherence tomography (OCT) in patients with NSTE-ACS:the FAST OCT study

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    Aims:There is a paucity of data on the performance of angiography-derived vessel fractional flow reserve (vFFR) in coronary artery lesions of patients presenting with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Optical coherence tomography (OCT) allows for visualization of lumen dimensions and plaque integrity with high resolution. The aim of this study was to define the association between vFFR and OCT findings in intermediate coronary artery lesions in patients presenting with NSTE-ACS. Methods and results:The FAST OCT study was a prospective, multicenter, single-arm study. Patients presenting with NSTE-ACS with intermediate to severe coronary artery stenosis in one or multiple vessels with TIMI 3 flow suitable for OCT imaging were eligible. Complete pre-procedural vFFR and OCT data were available in 226 vessels (in 188 patients). A significant association between vFFR and minimal lumen area (MLA) was observed, showing an average decrease of 20.4% (95% CI -23.9% to -16.7%) in MLA per 0.10 decrease in vFFR (adjusted P &lt; 0.001). vFFR &lt;= 0.80 showed a sensitivity of 56.7% and specificity of 92.5% to detect MLA &lt;= 2.5 mm2. Conversely, vFFR had a poor to moderate discriminative ability to detect plaque instability (sensitivity, 46.9%; specificity, 71.6%). Conclusion:In patients with NSTE-ACS, vFFR is significantly associated with OCT-detected MLA, and vFFR &lt;= 0.80 is highly predictive of the presence of significant disease based on OCT. Conversely, the sensitivity of vFFR &lt;= 0.80 to detect OCT-assessed significant disease was low, indicating that the presence of significant OCT findings cannot be ruled out based on a negative vFFR

    Procedural Performance of Ultrathin, Biodegradable Polymer-Coated Stents Versus Durable Polymer-Coated Stents Based on Intracoronary Imaging

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    OBJECTIVE: Thinner stent struts might lead to a higher risk of recoil and subsequently a smaller minimal stent area (MSA), which is known to be the strongest predictor of stent failure. We compared procedural performance between an ultrathin-strut biodegradable-polymer sirolimus-eluting stent (BP-SES) and a durable-polymer zotarolimus-eluting stent (DP-ZES) using intracoronary imaging.METHODS: A consecutive cohort of patients underwent percutaneous coronary intervention (PCI) with either BP-SES or DP-ZES in a pseudorandomized fashion between July 2018 and October 2019. In the present subanalysis, we included cases in which post-PCI imaging with intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was performed. The primary endpoint of the study was MSA. Secondary endpoints included percentage stent expansion and presence of residual edge disease, malapposition, tissue protrusion, submedial edge dissections, or edge hematoma.RESULTS: A total of 141 treated lesions (78 BP-SES and 63 DP-ZES) in 127 patients were analyzed. Median age was 69.3 years (interquartile range [IQR], 57.3-75.6) and 74.0% of patients were male. All baseline and procedural characteristics were comparable between both groups. Median MSA was 5.80 mm² (IQR, 4.40-7.24) for BP-SES and 6.35 mm² (IQR, 4.76-8.31) for DP-ZES (P=.15). No significant differences in stent expansion, residual edge disease and presence of malapposition, tissue protrusion, submedial edge dissections, or edge hematomas were found. Stent diameter and stent length were found to be independent predictors of MSA.CONCLUSIONS: No significant differences in MSA were found between lesions treated with BP-SES vs DP-ZES. BP-SES and DP-ZES were comparable in terms of procedural performance.</p

    Procedural Performance of Ultrathin, Biodegradable Polymer-Coated Stents Versus Durable Polymer-Coated Stents Based on Intracoronary Imaging

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    OBJECTIVE: Thinner stent struts might lead to a higher risk of recoil and subsequently a smaller minimal stent area (MSA), which is known to be the strongest predictor of stent failure. We compared procedural performance between an ultrathin-strut biodegradable-polymer sirolimus-eluting stent (BP-SES) and a durable-polymer zotarolimus-eluting stent (DP-ZES) using intracoronary imaging.METHODS: A consecutive cohort of patients underwent percutaneous coronary intervention (PCI) with either BP-SES or DP-ZES in a pseudorandomized fashion between July 2018 and October 2019. In the present subanalysis, we included cases in which post-PCI imaging with intravascular ultrasound (IVUS) or optical coherence tomography (OCT) was performed. The primary endpoint of the study was MSA. Secondary endpoints included percentage stent expansion and presence of residual edge disease, malapposition, tissue protrusion, submedial edge dissections, or edge hematoma.RESULTS: A total of 141 treated lesions (78 BP-SES and 63 DP-ZES) in 127 patients were analyzed. Median age was 69.3 years (interquartile range [IQR], 57.3-75.6) and 74.0% of patients were male. All baseline and procedural characteristics were comparable between both groups. Median MSA was 5.80 mm² (IQR, 4.40-7.24) for BP-SES and 6.35 mm² (IQR, 4.76-8.31) for DP-ZES (P=.15). No significant differences in stent expansion, residual edge disease and presence of malapposition, tissue protrusion, submedial edge dissections, or edge hematomas were found. Stent diameter and stent length were found to be independent predictors of MSA.CONCLUSIONS: No significant differences in MSA were found between lesions treated with BP-SES vs DP-ZES. BP-SES and DP-ZES were comparable in terms of procedural performance.</p
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