14 research outputs found
An Approximation Algorithm for Distance-Constrained Vehicle Routing on Trees
In the Distance-constrained Vehicle Routing Problem (DVRP), we are given a
graph with integer edge weights, a depot, a set of terminals, and a
distance constraint . The goal is to find a minimum number of tours starting
and ending at the depot such that those tours together cover all the terminals
and the length of each tour is at most .
The DVRP on trees is of independent interest, because it is equivalent to the
virtual machine packing problem on trees studied by Sindelar et al. [SPAA'11].
We design a simple and natural approximation algorithm for the tree DVRP,
parameterized by . We show that its approximation ratio is
, where , and in addition, that our
analysis is essentially tight. The running time is polynomial in and .
The approximation ratio improves on the ratio of 2 due to Nagarajan and Ravi
[Networks'12].
The main novelty of this paper lies in the analysis of the algorithm. It
relies on a reduction from the tree DVRP to the bounded space online bin
packing problem via a new notion of reduced length
Overinduction of CYP51A Gene After Exposure to Azole Antifungals Provides a First Clue to Resistance Mechanism in Fusarium solani Species Complex
International audienc
Strontium and tantalum based ferroelectric perovskite oxide materials
International audienc
Ferroelectricity and high tunability in novel strontium and tantalum based layered perovskite materials
International audienceThe present study reveals the ferroelectric nature of the novel (Sr2Ta2O7)100-x(La2Ti2O7)x layered perovskite materials and highlights a large variation of their permittivity under electric fields associated with very low dielectric loss in the radio-frequency range. More precisely, an ideal solid solution has been evidenced within the composition range 0 ≤ x ≤ 5 with lattice parameters and cell volume varying linearly with x. The relative permittivity also depends on the composition and reaches a maximum value (365 @10 kHz, RT), associated with a high tunability (17.6% @0.38 kV/mm) with very low dielectric loss lower than 2.10−3. Variation of the relative permittivity as a function of the temperature is also demonstrated, with the existence of a temperature maximum, increasing with the composition. Polarization-electric field (P-E) measurements feature hysteresis loops for compositions x ≥ 1.85, in conjunction with current peaks in the I-E curves originating from ferroelectric domains switching
Microwave dielectric and ferroelectric properties of strontium and tantalum based ferroelectric ceramics
International audienc
Nouvelles céramiques ferroélectriques de composition perovskite (Sr<sub>2</sub>Ta<sub>2</sub>O<sub>7</sub>)<sub>100-x</sub>(La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>)<sub>x</sub> : caractérisation diélectrique et ferroélectrique
National audienc
Elaboration of ferroelectric ceramics and thin films for miniaturized and agile antennas
Journée Des Doctorants de l'IET
Colchicine for Left Ventricular Infarct Size Reduction in Acute Myocardial Infarction: A Phase II, Multicenter, Randomized, Double-Blinded, Placebo-Controlled Study Protocol – The COVERT-MI Study
International audienceInflammatory processes have been identified as key mediators of ischemia-reperfusion injury in ST-segment elevation myocardial infarction (STEMI). They add damage to the myocardium and are associated with clinical adverse events (heart failure and cardiovascular death) and poor myocardial recovery. Colchicine is a well-known alkaloid with potent anti-inflammatory properties. In a proof-of-concept phase II trial, colchicine has been associated with a significant 50% reduction of infarct size (assessed by creatine kinase levels) in comparison to placebo in acute STEMI patients referred for primary percutaneous coronary intervention (PPCI). The Colchicine in STEMI Patients Study (COVERT-MI) is an ongoing confirmative prospective, multicenter, randomized, double-blind trial testing whether a short course oral treatment with colchicine versus placebo decreases myocardial injury in patients presenting with STEMI referred for PPCI. Adult patients, with a first STEMI episode and an initial TIMI flow ≤1, referred for PPCI, will be randomized (n = 194) in a 1:1 ratio to receive an oral bolus of colchicine of 2 mg followed by 0.5 mg b.i.d. treatment during 5 days or matching placebo. The primary endpoint will be the reduction in infarct size as assessed by cardiac magnetic resonance at 5 ± 2 days between both groups. The main secondary endpoints will be tested between groups in hierarchical order with left ventricular ejection fraction at 5 days, microvascular obstruction presence at 5 days, and absolute adverse left ventricular remodeling between 5 days and 3 months. This academic study is being financed by a grant from the French Ministry of Health (PHRCN-16-0357). Results from this study will contribute to a better understanding of the complex pathophysiology underlying myocardial injury after STEMI. The present study describes the rationale, design, and methods of the trial