L'homme du troisième millénaire face a l'incertitude. Quelle formation pour affronter l'incertitude?

In this paper we intend to establish the idea that a scientific formation can be an adequate background for future citizens to face the uncertainties of their own time. However, this requires questioning the distorted view of science given by society and, more particularly, by education. This article analyzes the origin of the contradiction between scientists activity and its interpretation in society and education and presents some alternative proposals to overcome it

Quelques reflexions sur le concept d'entropie issues d'un enseignement de thermodynamique

The authors establish the existence of a gap between physics' students conceptions concerning the notion of entropy and Clausius's, Boltzmann's, constructors of this concept. They analyze some basic features at the origin of these conceptions and some characteristics of the common sense interpretation of entropy. They conclude by some didactical propositions

Influencia de la formulación del enunciado y del control didáctico sobre la actividad intelectual de los alumnos en la resolución de problemas

Using as reference the scientist instead of the expert for analysing the pupil's behaviour in problem solving, we proposed to students (17 years old) closed and open problems. The great diversity of the students' productions and their analysis in the theoretical framework of didactical contract, oblige us to build two analysis grids: one of the students' activities and the other one for the finalities which we attribute to those activities. We show how ranging the strategy of resolution depends on the text of the problem

Cryptic diversity and database errors challenge non-indigenous species surveys: An illustration with Botrylloides spp. in the English Channel and Mediterranean Sea

Molecular tools have been extensively used in recent decades to examine biological invasion processes, and are increasingly being adopted as efficient tools to support non-indigenous species surveys, notably through barcoding approaches, i.e., the use of a reference sequence specific to a given species to validate its identification. The technique is easy to use but requires reliable reference sequences to be available in public databases. In addition, the increasing discovery of cryptic species in marine taxa may complicate taxonomic assignment. We illustrate these two issues in the ascidian genus Botrylloides, in which at least three global marine invaders have been recognized, including B. violaceus and B. diegensis. We obtained COI sequences from >750 colonies of Botrylloides spp. sampled in W Europe or provided by expert colleagues from other regions. Phylogenetic trees clearly distinguished our targeted taxa [i.e., B. violaceus, B. diegensis and B. leachii (native)]. They also revealed another discrete lineage apparently related to a recently described eastern Mediterranean species. By examining public databases, we found sequences of B. diegensis erroneously assigned to B. leachii. This observation has major implications as the introduced B. diegensis can be misidentified as a putatively native species. We also checked published sequences of the genus Botrylloides in the Mediterranean Sea, complemented with new samples. Based on our custom reference database, all published sequences of B. leachii corresponded to B. diegensis, although this NIS has hardly been reported at all in the Mediterranean region. Such database errors are unfortunate, as the barcoding approach is a powerful tool to identify the recognized Botrylloides species currently present in European seas. This is of particular importance because a trait often used during field assessment, i.e., single-color vs. two-color colonies, is misleading to distinguish B. violaceus and B. diegensis respectively: a substantial proportion of the single-color morph are actually B. diegensis in both the Mediterranean Sea and the English Channel. Altogether, this study exemplifies the advantages and disadvantages of molecular barcoding in NIS surveys and studies. The limitations that were identified are all easy to resolve once proper vouchers and collections are set up

Raisonnements dans la résolution de problèmes d'électrocinétique par les étudiants de licence

La résolution d'un problème de physique doit-elle consister en un exercice de calcul formel ou bien prendre en compte la signification attribuée aux symboles utilisés? Nous tentons de répondre à cette question à partir d'exercices d'électrocinétique (niveau bac+2) mettant en jeu les concepts de résistance équivalente et de tension.Is the problem solving in physics only an exercise of calculus with mathematic symbols (algebric reasoning) or is it necessary to know the significant of the symbols to solve the problem (qualitative reasoning) ? We try to answer this question with students at university level. We ask them exercises using the concepts of voltage and shunt

Enumerating Isolated Cliques in Temporal Networks

Isolation is a concept from the world of clique enumeration that is mostly used to model communities that do not have much contact to the outside world. Herein, a clique is considered isolated if it has few edges connecting it to the rest of the graph. Motivated by recent work on enumerating cliques in temporal networks, we lift the isolation concept to this setting. We discover that the addition of the time dimension leads to six distinct natural isolation concepts. Our main contribution is the development of fixed-parameter enumeration algorithms for five of these six clique types employing the parameter "degree of isolation". On the empirical side, we implement and test these algorithms on (temporal) social network data, obtaining encouraging preliminary results

Time to Virological Failure of 3 Classes of Antiretrovirals after Initiation of Highly Active Antiretroviral Therapy: Results from the EuroSIDA Study Group

Objective. The purpose of the present study was to determine the prevalence and incidence of virological triple drug-class failure (TCF) and to summarize the clinical outcome for patients who started receiving highly active antiretroviral therapy (HAART). Methods. The present study is an observational longitudinal study of 3496 treatment-experienced (TE) and treatment-naive (TN) patients monitored from the time they started receiving HAART (baseline) until TCF occurred (as determined on the basis of viral loads), until AIDS was newly diagnosed, or until death. Results. Four hundred forty-five patients (12.7%) had TCF; 370 (16.6%) of 2230 patients were TE, and 75 (5.9%) of 1266 patients were TN. At 6 years after starting HAART, 21.4% of TE and 11.2% of TN patients had TCF (P < .0001). The prevalence of TCF at or after 2002 was 15.5% in TE patients and 4.8% in TN patients. TN patients had a 32% annual increase in the incidence of TCF (95% confidence interval [CI], 14%-54%; P < .0001); at 5 years after starting HAART, the rate was comparable for TE and TN patients (3.3 and 3.4 cases/100 person-years of follow-up [PYFU], respectively). The incidence of new cases of AIDS or death was 2.7 cases/100 PYFU in patients who did not experience TCF and 5.0 cases/100 PYFU in patients who did experience TCF, an estimated 36% increase with each category of TCF (95% CI, 19%-56%; P < .0001). Conclusion. The prevalence of TCF was low after patients started receiving HAART, particularly among TN patients. Despite the influx of patients who had started receiving HAART more recently, the prevalence of TCF increased over calendar time. Patients with TCF had a higher incidence of newly diagnosed AIDS or death. Treatment of patients with TCF deserves further investigatio

Evaluating signatures of glacial refugia for North Atlantic benthic marine taxa

A goal of phylogeography is to relate patterns of genetic differentiation to potential historical geographic isolating events. Quaternary glaciations, particularly the one culminating in the Last Glacial Maximum ;21 ka (thousands of years ago), greatly affected the distributions and population sizes of temperate marine species as their ranges retreated southward to escape ice sheets. Traditional genetic models of glacial refugia and routes of recolonization include these predictions: low genetic diversity in formerly glaciated areas, with a small number of alleles/ haplotypes dominating disproportionately large areas, and high diversity including ‘‘private’’ alleles in glacial refugia. In the Northern Hemisphere, low diversity in the north and high diversity in the south are expected. This simple model does not account for the possibility of populations surviving in relatively small northern periglacial refugia. If these periglacial populations experienced extreme bottlenecks, they could have the low genetic diversity expected in recolonized areas with no refugia, but should have more endemic diversity (private alleles) than recently recolonized areas. This review examines evidence of putative glacial refugia for eight benthic marine taxa in the temperate North Atlantic. All data sets were reanalyzed to allow direct comparisons between geographic patterns of genetic diversity and distribution of particular clades and haplotypes including private alleles. We contend that for marine organisms the genetic signatures of northern periglacial and southern refugia can be distinguished from one another. There is evidence for several periglacial refugia in northern latitudes, giving credence to recent climatic reconstructions with less extensive glaciation