Temperature-dependent elasticity of microtubules

Central to the biological function of microtubules is their ability to modify their length which occurs by addition and removal of subunits at the ends of the polymer, both in vivo and in vitro. This dynamic behavior is strongly influenced by temperature. Here, we show that the lateral interaction between tubulin subunits forming microtubule is strongly temperature dependent. Microtubules deposited on prefabricated substrates were deformed in an atomic force microscope during imaging, in two different experimental geometries. Microtubules were modeled as anisotropic, with the Young's modulus corresponding to the resistance of protofilaments to stretching and the shear modulus describing the weak interaction between the protofilaments. Measurements involving radial compression of microtubules deposited on flat mica confirm that microtubule elasticity depends on the temperature. Bending measurements performed on microtubules deposited on lithographically fabricated substrates show that this temperature dependence is due to changing shear modulus, implying that the lateral interaction between the protofilaments is strongly determined by the temperature. These measurements are in good agreement with previously reported measurements of the disassembly rate of microtubules, demonstrating that the mechanical and dynamic properties of microtubules are closely related.

Super M, un videojoc per practicar les matemàtiques

Desenvolupament d'un videojoc per a Android i un videojoc per a navegador; tots dos relacionats amb la pràctica de les matemàtiques.

Robert Holcot, Postilla super librum Sapientiae.

Ecrit par le copiste Bertrand (f. 170v).

Commentarii super Aristotelem [dont: Isagoge (1-16v), Categoriae decem (19bis-54v)].

Ex-libris "S. Cornelii Compendiensis Congr. S. Mauri", suivi du chiffre 91B, XVIIe s., f. 1. Compiègne.

Fulgentius, Mythologie, phisica expositio super XII libros eneidorum (16), expositio sermonum ad Calcidium (20 v°). - Pauli et Senece epistole (22 v°). - Xenia M. Valerii Martialis (23). - Honorius, philosophia mundi (26 v°). - Prologus quorumdam juridicorum tractatuum (54 v°). - Ex Ausonio (55). -

Cordeliers.

Expositio Alani de Rupe super regulam b. Augustini.

Jacobins de la rue Saint-Honoré.

Postilla super epistolas et evangelia : tam de tempore quam de sancti : per totum anni circulum ([Reprod.]) / Hugonis de Sancto Charo

Collection : French books before 1601 ; 66.1

Michaelis Scoti super auctorem spherae cum quaestionibus... ([Reprod.])

Collection : Italian books before 1601 ; 59.5

Dialogua familiaris Alani et sodalis super deploratione calamitatis gallicane.

Franc. Philelfi orationes (34). - Philelfus Francisco Sforcie (92). - Guarinus Veron. Conrado Alcaldo (96). - De matrimonio inter Stephanum Salvanum et Margaritam Pontam (96 v°). - Plutarchus, de liberis educandis, interprete Garino Veron. (101).

Mercado Calú & Ângela e Palácio Finícia Controlo Interno como suporte estratégico de Gestão nas Empresas: os casos dos Super Mercado Calú & Ângela e Palácio Finícia

O presente trabalho intitula-se «Controlo Interno como suporte estratégico na Gestão das Empresas», pressupõe que todas as instituições devem ter um departamento de controlo interno para que possam desempenhar as suas actividades com eficiência e eficácia para alcançarem os objectivos estabelecidos pela administração. Porem, este trabalho teve como o principal objectivo definir e ampliar uma visão da importância do controlo interno nas instituições, pondo o foco no estudo de caso do Grupo Calú & Ângela, e Palácio Finícia. O controlo interno define-se como um conjunto de normas, procedimentos, instrumentos e acções utilizados pelas instituições ou empresas de uma forma sistematizada com o objectivo de assegurar o comprimento das normas e regulamentos internos.Partindo do pressuposto que, o controlo interno é uma ferramenta essencial para a gestão das instituições que prima pela salvaguarda dos seus activos e de prever eventuais riscos que possa pôr em causa a credibilidade das instituições, como, fraude, receptação de mercadorias diteoradas e fora do prazo, essas empresas devem ter um sistema de controlo interno robusta capaz de detectar essas situações constrangedoras. Portanto, os objectivos traçados e alcançados no trabalho é de uma interacção com o quotidiano das empresas comerciais em cabo verde, uma aproximação da teoria aprendida, e a prática desenvolvida durante o estágio curricular que teve uma metodologia virada pela pesquisas bibliográficas, pesquisas na internet, e aplicação do questionário.

HIV-1 co/super-infection in intravenous drug users.

BACKGROUND: The frequency of HIV-1 co/super-infection is unknown despite their implications for public health and vaccine development. This issue was addressed during an epidemic of both CRF11 and B subtype among intravenous drug users (IVDUs). METHODS: Bulk sequencing of reverse transcriptase, protease and C2V3 regions and subtype-specific nested polymerase chain reaction (PCR) in plasma and proviral DNA were performed using baseline and follow-up samples collected in recently infected IVDUs between 1998-2002 and in IVDUs with chronic infection living in the same area and presenting an unexpected rise of viremia (> 1 log10). RESULTS: In 58 recently infected patients, three B/CRF-11 co-infections, 25 B, 28 CRF-11 and two other subtypes were detected at baseline. In the three co-infected patients, both CRF-11 and B were detected in plasma and proviral DNA and persisted during follow-up. B- and CFR-11-specific PCR performed on follow-up samples of 40 of 58 recently infected patients (median follow-up, 14.5 months) revealed a transient B super-infection in a patient initially infected by CRF-11. Five of 156 chronic IVDUs (total follow-up: 346 years) had an unexpected rise of viremia. In two of them, aviremic without treatment for years after an initial B infection, a symptomatic CRF-11 super-infection occurred and was associated with high viral load and a fall of CD4 cell count. CONCLUSIONS: In recently infected IVDUs, co-infection B/CRF-11 is relatively frequent (5%). In chronically infected IVDUs super-infection may be transient and may occur in patients controlling efficiently HIV infection by the initial strain.