Paleogenetic and taphonomic analysis of human bones from Moa, Beirada, and Zé Espinho Sambaquis, Rio de Janeiro, Brazil

The present paper discusses mtDNA and taphonomy of human remains from Moa, Beirada, and Zé Espinho sambaquis of Saquarema, state of Rio de Janeiro, Brazil. New human bone dating by 14C-AMS for Moa archeological site (3810+50 BP - GX-31826-AMS) is included. Preservation of microscopic lamellae and DNA is not related to the macroscopic integrity of the bones. Results here suggest that the preservation of amplifiable DNA fragments may have relation to the preservation of the lamellar arrangement as indicated by optical microscopic examination (polarized light). In 13 human bone fragments from Moa, Beirada, and Zé Espinho it was possible to sequence mtDNA from the 3 individuals of Moa, and from 1 of 4 individuals of Beirada, whose bones also show extensive areas with preserved lamellar structures. The 6 human bone fragments of Zé Espinho and 3 of the 4 fragments of Beirada showed extensive destruction of cortical microstructure represented by cavities, intrusive minerals, and agglomerated microscopic bodies of fungi and bacteria; it was not possible to extract mtDNA from these samples. The results support the hypothesis that the preservation of the microscopic osteon organization is a good predictor for DNA preservation. It was also confirmed the C haplogroup antiquity in Brazil.

Anti-flagellin antibody responses elicited in mice orally immunized with attenuated Salmonella enterica serovar Typhimurium vaccine strains

In the present study we investigated the flagellin-specific serum (IgG) and fecal (IgA) antibody responses elicited in BALB/c mice immunized with isogenic mutant derivatives of the attenuated Salmonella enterica serovar Typhimurium (S. Typhimurium) SL3261 strain expressing phase 1 (FliCi), phase 2 (FljB), or no endogenous flagellin. The data reported here indicate that mice orally immunized with recombinant S. Typhimurium strains do not mount significant systemic or secreted antibody responses to FliCi, FljB or heterologous B-cell epitopes genetically fused to FliCi. These findings are particularly relevant for those interested in the use of flagellins as molecular carriers of heterologous antigens vectored by attenuated S. Typhimurium strains.

Colour image processing

In the context of the round table the following topics related to image colour processing will be discussed: historical point of view. Studies of Aguilonius, Gerritsen, Newton and Maxwell. CIE standard (Commission International de lpsilaEclaraige). Colour models. RGB, HIS, etc. Colour segmentation based on HSI model. Industrial applications. Summary and discussion. At the end, video images showing the robustness of colour in front of B/W images will be presented

Estudi i aplicació de llibreries de física per a motors de videojocs

En el món dels videojocs el realisme és un punt molt important a tenir en compte ja que dónamés sensació a l’usuari d’estar immers en el videojoc. Això passa en part per aconseguir realisme en la dinàmica dels objectes i fer que aquests segueixin les lleis de la física de Newton. Per això s’han desenvolupat diverses llibreries que s’anomenen “motors de física” (physics engines), que empren variables com la massa, la velocitat, la fricció i la resistència del vent. Els objectius d’aquest projecte seran l’estudi de diferents llibreries físiques existents, la seva comparació i com s’integren en els motors de jocs. A més a més , la generació de contingut amb comportament que respongui a les funcions definides a aquestes llibreries no és trivial i per aquest motiu també es desenvoluparà una aplicació per generar murs de forma semiautomàtica que respongui a impactes. Per assolir aquests objectius caldrà: d’ una banda, comparar els cossos rígids, unions i funcionament en general de diferents llibreries físiques: Newton Game Dynamics, NVIDIA PhysX Technology, Open Dynamics Engine, Bullet PhysicsLibrary, Tokamak Physics Engine i Havok i d’ altra banda, implementar una aplicació que donant-li una imatge en planta d’una paret o conjunt de parets en format vectorial i les mides d’un maó, generi murs que puguin reaccionar de forma adequada quan rebin l’impacte d’una massa determinada. L’aplicació s’implementarà en C++ i amb l’entorn de desenvolupament Microsoft Visual Studio 2005. La visualització serà amb OpenGL

Blood pressure loci identified with a gene-centric array.

Raised blood pressure (BP) is a major risk factor for cardiovascular disease. Previous studies have identified 47 distinct genetic variants robustly associated with BP, but collectively these explain only a few percent of the heritability for BP phenotypes. To find additional BP loci, we used a bespoke gene-centric array to genotype an independent discovery sample of 25,118 individuals that combined hypertensive case-control and general population samples. We followed up four SNPs associated with BP at our p < 8.56 × 10(-7) study-specific significance threshold and six suggestively associated SNPs in a further 59,349 individuals. We identified and replicated a SNP at LSP1/TNNT3, a SNP at MTHFR-NPPB independent (r(2) = 0.33) of previous reports, and replicated SNPs at AGT and ATP2B1 reported previously. An analysis of combined discovery and follow-up data identified SNPs significantly associated with BP at p < 8.56 × 10(-7) at four further loci (NPR3, HFE, NOS3, and SOX6). The high number of discoveries made with modest genotyping effort can be attributed to using a large-scale yet targeted genotyping array and to the development of a weighting scheme that maximized power when meta-analyzing results from samples ascertained with extreme phenotypes, in combination with results from nonascertained or population samples. Chromatin immunoprecipitation and transcript expression data highlight potential gene regulatory mechanisms at the MTHFR and NOS3 loci. These results provide candidates for further study to help dissect mechanisms affecting BP and highlight the utility of studying SNPs and samples that are independent of those studied previously even when the sample size is smaller than that in previous studies.

Collectio sermonum de dominicis, de festis et de sanctis, ad usum Fratrum Minorum.

« Sermo adaptabillis b. Laurentio... Dispersit, dedit pauperibus... Quia secundum b. Dionixium in De ecclesiastica Yerarchia... » (1-2) ; — « Sermo de assumptione b. Marie... Quid hoc audio de te... Quid nos tantilly... » (2v-3), suivi d'une note à l'usage des prédicateurs : « Nota quod ne sermo sit deffectuosus... » (3) ; — « Sermo de conceptione b. Marie. Que est ista que progreditur... Karissimi, predicator evangelicus, beatitudinis eterne preco... » (3v-4v) ; — « Sermo de quatuor festis principalibus b. Marie... Que est ista que progreditur... Verba ista sunt tocius curie celestis... » (4v-5v) ; — « Sermo de Purificatione. In mansuetudine suscipite... Secundum b. Gregorium, Mor. 23... » (6-7) ; — « Sermo de b. Francischo... Cujus est ymago hec et superscriptio... Secundum b. Gregorium, omelia 30... » (7v-8v) ; — « Sermo in dominica [in Quinquagesima]. Ecce ascendimus Jerosolimam... Karissimi, sicut scitis, finis est... » (9-10) ; — [Sermo in dominica IIa post Epiphaniam] « Tu servasti vinum bonum usque adhuc... In verbis istis spiritualiter intellectus... » (10-10v) ; — « Sermo de b. Francischo. Ad ymaginem similitudinis sue... Verba ista ad litteram scripta... » (11-12) ; — « Sermo de b. Johane Baptista. Magnus es tu et faciens mirabilia... Secundum Gregorium quia tute... » (12v-13) ; — « Sermo de angelis. Inmittit angelus Domini... Sanctus ille David, acceptus de ovibus... » (13v-14) ; — « In ascensione Domini. Exultavit ut gigas... Duo sunt inter cetera Christi misteria... » (14v-16) ; — « De asumpcione Domine nostre. Ad preceptum tuum elevabitur aquila... Quia, karissimi, Mater Domini... » [FRANCISCUS DE MAYRONIS] ; cf. éd. Bâle, 1498, f. CIV-CIIIV, avec variantes (16v-18) ; — « De Maria Magdalena. Permittuntur [sic pro : Remittuntur] tibi peccata tua... Sicut solent maximi principes... » [Idem], sermon abrégé ; cf. éd. cit., f. LXXXVIIIV-XCI (18-19v) ; — « De s. Johane Evangelista. Dillectus meus michi... Ostenditur b. Johannes prout inflamatus... » [Idem], résumé ; cf. éd. cit., f. XXIX-XXIXV (20) ; — « In festo apostolorum Petri et Pauli. Accepimus gratiam et apostolatum... Gloriosissimi christiane fidei religionis... » (20v-23v) ; — « Sermo de gratia divina acquirenda. Accepimus gratiam etc. Vivat, obsecro, anima mea ... quoniam... » (24) ; — « Accepimus gratiam etc. Restat ostendere via physionomica... » (24v-26) ; — « Sermo de beatitudine, sive gloria celesti, sive in festo Omnium sanctorum. Fons sapientie verbum Dei... Ecce ego sto prope fontem... In hoc festo precipue et anno... » (26-29) ; — « De nativitate Domine nostre. Egredietur virga de radice Jesse... Percutiet terram virga... Clementissimus pastor ovium... » (29v-32) ; — « Sermo de uno confessore pontifice. Rector fratrum et stabilimentum populi... Inter viros eximie sanctitatis... » (32v) ; — « De nativitate Domini. Transeamus usque Bethelem... Innocencius in quodam sermone de predicatione... » (34v-36) ; — « In die nativitatis Domini. Sol ortus est et humiles exaltati sunt... Beatus Augustinus, De Civitate Dei : Anima participacione... » (36-37v) ; — « Dominica infra octavas Nativitatis. Ecce positus est hic in ruinam... Secundum doctrinam Philosophi in diversis locis... » (38-38v) ; — « Dominica quarta in quadragesima. Sequebatur eum multitudo magna... Secundum Damascenum libro primo, capitulo XV°, diversitas actionum... » (39-40v) ; — « De Canane[a], dominica secunda [sic] in quadragesima [Feria 5a post dom. Ia in XLa]. Dimitte illam quia clamat... Si attendamus ordinem generacionis... » (41-42v) ; — « Dominica de Passione. Si veritatem dico vobis... Secundum sententiam Phylosophi primo Metaphysice... » (43-43v) ; — « In cena Domini. Hodie est rex et cras morietur... Omne agens ordinate prius inquirit... » (44-45) ; — « De resurectione. Hec dies quam fecit Dominus... Scilicet est ex dictis Philosophi in diversis locis... » (45v-47) ; — « Dominica in Quadragesima. Ecce nunc tempus acceptabile... Ut dicit Philosophus, secundo de Celo et mundo... » (47-48v) ; — « De b. Clara. Sicut lux meridiana clara est... Secundum Philosophum tertio Methaphysice, si res creatas... » (48v-49v) ; — « Sermo de Cruce. Vidit mulier quod bonum esset lignum... Sicut ex doctrina Philosophi primo Ethicorum... » (50-51) ; — « De s. Anthonio. Misit servum suum hora cene... Sicut in rebus naturalibus docet experiencia... » (51v-52v) ; — « De b. Johane Batista. Tu puer propheta Altissimi... Secundum doctrinam Hugonis in commento de angelica Jerarchia... » (53-54) ; — « De b. Bertholameo [sic]. Dedit illi contra inimicos potenciam... Racio docet et experiencia manifestat... » (54v-55) ; — « De b. Francischo. Amice, ascende superius... Dicit Philosophus quinto Physicorum quod motus... » (55v-56) ; — [De b. Bernardo] « Omnia parata sunt, venite ad nupcias... Sicut videmus in motu naturali... » (56v-57) ; — « De sacerdote novo. Vos elegit Dominus... Ut potest haberi ex dictis Dyonisii... » (57v-58v) ; — « De assumpcione Virginis gloriose. Elevetur tronus David super Israel... Videmus quod triplici racione aliqua corpora... » (58v-59v) ; — « De assumpcione Virginis. Veni de Libano sponsa mea... Secundum testimonium Scripturarum et humane consuetudinis... » (59v-61) ; — « De Trinitate. Tripliciter sol exurens montes... Secundum quod dicit Philosophus, tota nostra noticia... » (61-61v) ; — « De b. Francischo. Hic beatus in facto suo erit... Post doctrinam philosophorum et experienciam... » (62-62v) ; — [De b. Eligio] « Provideat rex virum sapientem... Secundum sententiam (secundum) sapientis primo Metaphysice . » (63-64) ; — « De resurrectione Domini. Tercia dies est hodie... Tripliciter alicujus rei non vise accipimus fidem certam... » (64-65) ; — «Stetit in medio discipulorum et dixit : Pax vobis... Ut dicit b. Augustinus undevicesimo de Civitate Dei... » (65v-67) ; — « De Omnibus sanctis... Gloriosa dicta sunt de te... Aperta est civitas... Doctore egregio Bernardo scilicet attestante... » (67-69) ; — « De b. Johane Batista. Hic venit in testimonium... Sicut potest probari ex dictis Philosophi et exemplis... » (69v-70) ; — « De b. Petro apostolo. Tu pasce populum meum Israel... Secundum sententiam Philosophi tertio Politicorum... » (70v-71) ; — « De assumpcione Virginis gloriose. Transibo in locum tabernaculi... Triplici ratione secundum philosophorum doctrinam aliqua moventur... » (71v-72v) ; — [De b. Francisco] « Adolescens, tibi dico surge... Consideranti sciderum revolucionem... » (73-74v) ; — [De s. Michaele] « Michael et angeli preliabantur... Sicut ex doctrina Phylosophi in pluribus locis patet... » (74v-76) ; — « De b. Nicholao. Petra fundebat michi rivos olei... Secundum philosophicam doctrinam, diversitas effectuum... » (76-77) ; — « In festo apostolorum Petri et Pauli. Fecit Deus duo luminaria magna... Secundum sententiam Philosophi secundo Methaphysice... » (77v-78) ; — « De b. Bertholameo. Vidi angelum fortem... Secundum dictum Philosophi, omnes transferentes... » (78v-79) ; — « Dominica in Quadragesima. Ductus est Jhesus in desertum... Sicut naturalium operationum multiplex experiencia... » (79v-80v) ; — « De s. Thoma apostolo. Ecce cognovi quoniam Deus meus es... Bernardus in sermone : Deus noverim me... » (81-81v) ; — « De sacerdote novo. Misit Dominus servum suum... Secundum quod dicit Philosophus primo Ethicorum, diversarum operationum... » (82-82bis) ; — « In purificatione Virginis. Parasti ante faciem omnium populorum... Si attendamus formationem rerum temporalium... » (82bisv-83v) ; — « De uno martire. Esto vir fortis, et prelia bella Domini... Secundum consuetudinem hominum... » (84-85) ; — « De festo Purificacionis. Lucerna splendens super candelabrum... Doctrina philosophorum et tradit... » (85v-86v) ; — « Feria quarta Cinerum. Cum jejunas unge caput tuum... Morum Philosophi doctrinam perlegens et attendens... » (87-88v) ; — « In quarta feria Cinerum. Cum jejunatis, nolite fieri sicut ypocrite... Sicut ex doctrina Philosophi primo Ethicorum potest colligi... » (88v-89v) ; — « In festo b. Lodovici [episcopi]. Surrexit rex de solio suo... Ut dicit Philosophus quarto Methaphysicorum... » (90-91v) ; — « De b. Jacobo. Vox tonitrui tui in rota... Secundum doctrinam philosophicam formarum naturalium... » (91v-92v) ; — [In festo Annunciationis] « Ecce concipies in utero... Secundum doctrinam Philosophi septimo de Animalibus, ad generationem... » (93-94) ; — « De s. Ludovico [episcopo]. Reposita est michi corona justitie... Secundum sententiam Philosophi secundo Phisicorum, omne agens... » (94-96).

Prevalence of plasmid-mediated quinolone resistance determinants among oxyiminocephalosporin-resistant Enterobacteriaceae in Argentina

High quinolone resistance rates were observed among oxyiminocephalosporin-resistant enterobacteria. In the present study, we searched for the prevalence of plasmid-mediated quinolone resistance (PMQR) genes within the 55 oxyiminocephalosporin-resistant enterobacteria collected in a previous survey. The main PMQR determinants were aac(6')-Ib-cr and qnrB, which had prevalence rates of 42.4% and 33.3%, respectively. The aac(6')-Ib-crgene was more frequently found in CTX-M-15-producing isolates, while qnrB was homogeneously distributed among all CTX-M producers.

L'aportació de Tomàs Cerdà en la introducció del càlcul diferencial i integral a l'Espanya del segle XVIII

El desenvolupament del càlcul diferencial i integral com a disciplina científica a Europa durant el segle XVIII no és un tema nou. Però s’ha acostumat a enfocar la visió d’aquesta formació molt sovint des del “centre” i a partir de les grans figures com Isaac Newton o Gottfried Wilhelm Leibniz. En el present treball el protagonista potser, per a molts, no és una figura de primera línia; Tomàs Cerdà, és un ensenyant a Barcelona i a Madrid durant la segona meitat del segle XVIII, que “tradueix” al castellà autors anglesos, però que amb la seva pràctica està realment introduint el nou càlcul a Espanya i donant, de fet, una orientació d’aquesta nova disciplina als seus deixebles. El com i per què Cerdà decideix quin serà el seu guia en la introducció del càlcul diferencial i integral i quines seran les seves pròpies aportacions en aquesta labor seran els temes centrals del nostre treball. La nostra tasca ha anat, així doncs, a entendre millor, el procés de divulgació del coneixement científic, veient-lo en tot moment com formant part activa del mateix procés de construcció d’aquest coneixement.

Blood pressure loci identified with a gene-centric array.

Raised blood pressure (BP) is a major risk factor for cardiovascular disease. Previous studies have identified 47 distinct genetic variants robustly associated with BP, but collectively these explain only a few percent of the heritability for BP phenotypes. To find additional BP loci, we used a bespoke gene-centric array to genotype an independent discovery sample of 25,118 individuals that combined hypertensive case-control and general population samples. We followed up four SNPs associated with BP at our p < 8.56 × 10(-7) study-specific significance threshold and six suggestively associated SNPs in a further 59,349 individuals. We identified and replicated a SNP at LSP1/TNNT3, a SNP at MTHFR-NPPB independent (r(2) = 0.33) of previous reports, and replicated SNPs at AGT and ATP2B1 reported previously. An analysis of combined discovery and follow-up data identified SNPs significantly associated with BP at p < 8.56 × 10(-7) at four further loci (NPR3, HFE, NOS3, and SOX6). The high number of discoveries made with modest genotyping effort can be attributed to using a large-scale yet targeted genotyping array and to the development of a weighting scheme that maximized power when meta-analyzing results from samples ascertained with extreme phenotypes, in combination with results from nonascertained or population samples. Chromatin immunoprecipitation and transcript expression data highlight potential gene regulatory mechanisms at the MTHFR and NOS3 loci. These results provide candidates for further study to help dissect mechanisms affecting BP and highlight the utility of studying SNPs and samples that are independent of those studied previously even when the sample size is smaller than that in previous studies.

New delay-dependent stability criteria for uncertain neutral systems with mixed time-varying delays and nonlinear perturbations

The problem of stability analysis for a class of neutral systems with mixed time-varying neutral, discrete and distributed delays and nonlinear parameter perturbations is addressed. By introducing a novel Lyapunov-Krasovskii functional and combining the descriptor model transformation, the Leibniz-Newton formula, some free-weighting matrices, and a suitable change of variables, new sufficient conditions are established for the stability of the considered system, which are neutral-delay-dependent, discrete-delay-range dependent, and distributeddelay-dependent. The conditions are presented in terms of linear matrix inequalities (LMIs) and can be efficiently solved using convex programming techniques. Two numerical examples are given to illustrate the efficiency of the proposed method

Theoretical study of the second-order vibrational Stark effect

The behaviour of the harmonic infrared frequency of diatomic molecules subjected to moderate static uniform electric fields is analysed. The potential energy expression has been developed as a function of a static uniform electric field, which brings about a formulation describing the frequency versus field strength curve. With the help of the first and second derivatives of the expressions obtained, which correspond to the first- and second-order Stark effects, it was possible to find the maxima of the frequency versus field strength curves for a series of molecules using a Newton-Raphson search. A method is proposed which requires only the calculation of a few energy derivatives at a particular value of the field strength. At the same time, the expression for the dependence of the interatomic distance on the electric field strength is derived and the minimum of this curve is found for the same species. Derived expressions and numerical results are discussed and compared with other studi

Orthotropic active strain models for the numerical simulation of cardiac biomechanics

An active strain formulation for orthotropic constitutive laws arising in cardiac mechanics modeling is introduced and studied. The passive mechanical properties of the tissue are described by the Holzapfel-Ogden relation. In the active strain formulation, the Euler-Lagrange equations for minimizing the total energy are written in terms of active and passive deformation factors, where the active part is assumed to depend, at the cell level, on the electrodynamics and on the specific orientation of the cardiac cells. The well-posedness of the linear system derived from a generic Newton iteration of the original problem is analyzed and different mechanical activation functions are considered. In addition, the active strain formulation is compared with the classical active stress formulation from both numerical and modeling perspectives. Taylor-Hood and MINI finite elements are employed to discretize the mechanical problem. The results of several numerical experiments show that the proposed formulation is mathematically consistent and is able to represent the main key features of the phenomenon, while allowing savings in computational costs.

Effects of long-term averaging of quantitative blood pressure traits on the detection of genetic associations.

Blood pressure (BP) is a heritable, quantitative trait with intraindividual variability and susceptibility to measurement error. Genetic studies of BP generally use single-visit measurements and thus cannot remove variability occurring over months or years. We leveraged the idea that averaging BP measured across time would improve phenotypic accuracy and thereby increase statistical power to detect genetic associations. We studied systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP) averaged over multiple years in 46,629 individuals of European ancestry. We identified 39 trait-variant associations across 19 independent loci (p < 5 × 10(-8)); five associations (in four loci) uniquely identified by our LTA analyses included those of SBP and MAP at 2p23 (rs1275988, near KCNK3), DBP at 2q11.2 (rs7599598, in FER1L5), and PP at 6p21 (rs10948071, near CRIP3) and 7p13 (rs2949837, near IGFBP3). Replication analyses conducted in cohorts with single-visit BP data showed positive replication of associations and a nominal association (p < 0.05). We estimated a 20% gain in statistical power with long-term average (LTA) as compared to single-visit BP association studies. Using LTA analysis, we identified genetic loci influencing BP. LTA might be one way of increasing the power of genetic associations for continuous traits in extant samples for other phenotypes that are measured serially over time.

Total knee arthroplasty - a clinical and numerical study of the micromovements of the tibial implant

Introduction The importance of the micromovements in the mechanism of aseptic loosening is clinically difficult to evaluate. To complete the analysis of a series of total knee arthroplasties (TKA), we used a tridimensional numerical model to study the micromovements of the tibial implant.Material and Methods Fifty one patients (with 57 cemented Porous Coated Anatomic TKAs) were reviewed (mean follow-up 4.5 year). Radiolucency at the tibial bone-cement interface was sought on the AP radiographs and divided in 7 areas. The distribution of the radiolucency was then correlated with the axis of the lower limb as measured on the orthoradiograms.The tridimensional numerical model is based on the finite element method. It allowed the measurement of the cemented prosthetic tibial implant's displacements and the microvements generated at bone-ciment interface. A total load (2000 Newton) was applied at first vertically and asymetrically on the tibial plateau, thereby simulating an axial deviation of the lower limbs. The vector's posterior inclination then permitted the addition of a tangential component to the axial load. This type of effort is generated by complex biomechanical phenomena such as knee flexion.Results 81 per cent of the 57 knees had a radiolucent line of at least 1 mm, at one or more of the tibial cement-epiphysis jonctional areas. The distribution of these lucent lines showed that they came out more frequently at the periphery of the implant. The lucent lines appeared most often under the unloaded margin of the tibial plateau, when axial deviation of lower limbs was present.Numerical simulations showed that asymetrical loading on the tibial plateau induced a subsidence of the loaded margin (0-100 microns) and lifting off at the opposite border (0-70 microns). The postero-anterior tangential component induced an anterior displacement of the tibial implant (160-220 microns), and horizontal micromovements with non homogenous distribution at the bone-ciment interface (28-54 microns).Discussion Comparison of clinical and numerical results showed a relation between the development of radiolucent lines and the unloading of the tibial implant's margin. The deleterious effect of lower limbs' axial deviation is thereby proven. The irregular distribution of lucent lines under the tibial plateau was similar of the micromovements' repartition at the bone-cement interface when tangential forces were present. A causative relation between the two phenomenaes could not however be established.Numerical simulation is a truly useful method of study; it permits to calculate micromovements which are relative, non homogenous and of very low amplitude. However, comparative clinical studies remain as essential to ensure the credibility of results.

L'equilibri en la força

Aquesta unitat didàctica desenvolupada durant el Màster de Professorat de Secundària està pensada per ser impartida a l’assignatura Física i Química de 4t d’ESO, més concretament a la part de física, com introducció a la Dinàmica. Es parteix de les idees prèvies de l’alumnat sobre situacions quotidianes on hi actuen forces. Es contrasten aquestes amb una posada en comú i amb l’explicació del professor, que va introduint progressivament conceptes nous com l’equilibri o els vectors, a mesura que es fan necessaris. En les sessions posteriors s’insisteix en el caràcter vectorial de les forces i es centra l’atenció en dos casos particulars: la força de fregament i la força elàstica. Sobre aquestes dues es treballa resolent un cas i fent una experiència pràctica, fomentant la competència comunicativa. La finalitat de la metodologia és acabar construint les Lleis de Newton, les quals hauran d’exposar en una presentació al final de la unitat.