1,910 research outputs found
Quel effet cela fait, de mordre dans un citron?
Le thème de la conscience a connu un regain d’intérêt spectaculaire, ces dernières années, chez les philosophes et les scientifiques. Des théories nouvelles ont vu le jour dans l’espoir de rendre compte de « l’effet que cela fait », par exemple, de tomber amoureux, de se faire mal ou de… mordre dans un citron. Contrairement à une conception populaire, de nombreux chercheurs ont suggéré que ressentir quelque chose équivalait en réalité à se représenter quelque chose. L’ouvrage "Conscience et représentation. Introduction aux théories représentationnelles de l’esprit" (Paris, Vrin, 2016) dresse un état des lieux des controverses liées à cette question
On the nonparametric inference of coefficients of self-exciting jump-diffusion
In this paper, we consider a one-dimensional diffusion process with jumps
driven by a Hawkes process. We are interested in the estimations of the
volatility function and of the jump function from discrete high-frequency
observations in a long time horizon which remained an open question until now.
First, we propose to estimate the volatility coefficient. For that, we
introduce a truncation function in our estimation procedure that allows us to
take into account the jumps of the process and estimate the volatility function
on a linear subspace of L2(A) where A is a compact interval of R. We obtain a
bound for the empirical risk of the volatility estimator, ensuring its
consistency, and then we study an adaptive estimator w.r.t. the regularity.
Then, we define an estimator of a sum between the volatility and the jump
coefficient modified with the conditional expectation of the intensity of the
jumps. We also establish a bound for the empirical risk for the non-adaptive
estimators of this sum, the convergence rate up to the regularity of the true
function, and an oracle inequality for the final adaptive estimator.Finally, we
give a methodology to recover the jump function in some applications. We
conduct a simulation study to measure our estimators' accuracy in practice and
discuss the possibility of recovering the jump function from our estimation
procedure
Environmental assessment of bioethanol from onshore grown Ulva
PosterBesides biofuels from microalgae, an emerging interest in using macroalgae as feedstock for biofuel production is observable. Macroalgae have the advantage that they are much easier to harvest than microalgae so that the problem of low feedstock concentration does not arise. The environmental performance of bioethanol from onshore grown green algae is assessed using literature data and initial laboratory scale data. The optimized system model allows for producing an environmentally efficient biofuel in comparison to fossil fuel and bioethanol from sugar cane. Handling the co-product by substitution instead of energy allocation significantly reduced the environmental impacts of the system and resulted in environmental bonuses in several impact categories. Thus, the management of the co-product in the LCA model (energy allocation vs. substitution) is a key step in the LCA, as it highly influences the impact assessment results
Indium catalysts for low-pressure CO2/epoxide ring-opening copolymerization: Evidence for a mononuclear mechanism?
The alternating copolymerization of CO2/epoxides is a useful means to incorporate high levels of carbon dioxide into polymers. The reaction is generally proposed to occur by bimetallic or bicomponent pathways. Here, the first indium catalysts are presented, which are proposed to operate by a distinct mononuclear pathway. The most active and selective catalysts are phosphasalen complexes, which feature ligands comprising two iminophosphoranes linked to sterically hindered ortho-phenolates. The catalysts are active at 1 bar pressure of carbon dioxide and are most effective without any cocatalyst. They show low-pressure activity (1 bar pressure) and yield polymer with high carbonate linkage selectivity (>99%) and isoselectivity ( Pm > 70%). Using these complexes, it is also possible to isolate and characterize key catalytic intermediates, including the propagating indium alkoxide and carbonate complexes that are rarely studied. The catalysts are mononuclear under polymerization conditions, and the key intermediates show different coordination geometries: the alkoxide complex is pentacoordinate, while the carbonate is hexacoordinate. Kinetic analyses reveal a first-order dependence on catalyst concentration and are zero-order in carbon dioxide pressure; these findings together with in situ spectroscopic studies underpin the mononuclear pathway. More generally, this research highlights the future opportunity for other homogeneous catalysts, featuring larger ionic radius metals and new ligands, to operate by mononuclear mechanisms
Nomogram Predicting the Likelihood of Parametrial Involvement in Early-Stage Cervical Cancer: Avoiding Unjustified Radical Hysterectomies
Background: We aimed to establish a tool predicting parametrial involvement (PI) in patients with early-stage cervical cancer and select a sub-group of patients who would most benefit from a less radical surgery. Methods: We retrospectively reviewed patients from two prospective multicentric databases—SENTICOL I and II—from 2005 to 2012. Patients with early-stage cervical cancer (FIGO 2018 IA with lympho-vascular involvement to IIA1), undergoing radical surgery (hysterectomy or trachelectomy) with bilateral sentinel lymph node (SLN) mapping with no metastatic node or PI on pre-operative imaging, were included. Results: In total, 5.2% patients (11/211) presented a histologic PI. After univariate analysis, SLN status, lympho-vascular space invasion, deep stromal invasion and tumor size were significantly associated with PI and were included in our nomogram. Our predictive model had an AUC of 0.92 (IC95% = 0.86–0.98) and presented a good calibration. A low risk group, defined according to the optimal sensitivity and specificity, presented a predicted probability of PI of 2%. Conclusion: Patients could benefit from a two-step approach. Final surgery (i.e. radical surgery and/or lymphadenectomy) would depend on the SLN status and the probability PI calculated after an initial conization with bilateral SLN mapping
Percutaneous angioplasty with drug eluting balloon for infra-inguinal venous bypass stenosis
peer reviewe
Angiosome concept for vascular interventions
editorial reviewe
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