The viral replication cycle is controlled by information transduced through both molecular and mechanical interactions. Viral infection mechanics remains largely unexplored, however, due to the complexity of cellular mechanical responses over the course of infection as well as a limited ability to isolate and probe these responses. Here, we develop an experimental system consisting of herpes simplex virus type 1 (HSV-1) capsids bound to isolated and reconstituted cell nuclei, which allows direct probing of capsid–nucleus mechanics with atomic force microscopy (AFM). Major mechanical transformations occur in the host nucleus when pressurised viral DNA ejects from HSV-1 capsids docked at the nuclear pore complexes (NPCs) on the nuclear membrane. This leads to structural rearrangement of the host chromosome, affecting its compaction. This in turn regulates viral genome replication and transcription dynamics as well as the decision between a lytic or latent course of infection. AFM probing of our reconstituted capsid–nucleus system provides high-resolution topographical imaging of viral capsid docking at the NPCs as well as force volume mapping of the infected nucleus surface, reflecting mechanical transformations associated with chromatin compaction and stiffness of nuclear lamina (to which chromatin is tethered). This experimental system provides a novel platform for investigation of virus–host interaction mechanics during viral genome penetration into the nucleus.

Hemostasis, a process which causes bleeding to stop, can be enhanced using chitosan; but the detailed mechanism is unclear. Red blood cells (RBCs) adhere to chitosan because of their opposite charges, but the adhesion force is small, 3.83 pN as measured here using an optical tweezer, such that the direct adhesion cannot be the sole cause for hemostasis. However, it was observed in this study that layer structures of aggregated RBCs were formed next to chitosan objects in both static and flowing environments, but not formed next to cotton and rayon yarns. The layer structure is the clue for the initiation of hemostatsis. Through the supporting measurements of zeta potentials of RBCs and pH's using blood-chitosan mixtures, it is proposed here that the formation of the RBC layer structure next to chitosan objects is due to the reduction of repulsive electric double layer force between RBCs, because of the association of H+ deprotonated from chitosan with COO− on RBC membrane, under the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results are beneficial for designing effective chitosan-based wound dressings, and also for general biomedical applications.

By limiting its objective to correcting dysmorphisms of the dento-alveolar arches, current treatment of malocclusions loses a great deal of effectiveness that technical procedures might otherwise achieve. An inadequate understanding of the mechanics of the facial envelope can allow the dysmorphisms and breathing dysfunctions associated with malocclusions to persist.

However, the oral fissure has a profound impact on the mechanical behavior of the facial envelope. Like an operational command, it transforms the local mechanics of the facial envelope by creating a phenomenon of a concentration of stress and deformations whose manifestations are visible not only on facial soft tissues, but also on their cartilage and osseous supports. This phenomenon also influences the physiology of the facial muscles by distorting them as they are forced to adapt to the fissure, and by guiding the functional adaptations of the envelope.

Basically, the impact of this phenomenon on the structural organization of the facial envelope is transformed by the oronasal morphophysiologic integration of the structures of the face and practitioners must necessarily adapt their therapy to address these problems. Finally, the functional relationship between the nasal mucosa and the cavernous sinus increasingly broadens orthopedic perspectives for therapy that will most importantly encompass the cephalic hypothalamic-pituitary axis.

The effectiveness of a procedure appropriately initiated by practitioners of DFO due to their specific expertise will require them to exercise a greater attentiveness to the global functionality of this complex into which the face is integrated.

The presence of strain distributions within semiconductor features influences many aspects of their behavior. For example, microelectronic technology that incorporates strained silicon improves device performance by increasing carrier mobility in the Si channels. Because current semiconductor fabrication contains multiple levels of metallic and dielectric structures, an understanding of the mechanical response of the constituent elements is critical to the prediction of the overall device performance. In addition, the interaction of strain fields between adjacent structures becomes greater as feature sizes decrease and the corresponding feature density increases. The use of synchrotron-based X-ray methods allows one to determine the interaction between strained features and their environment at a submicron resolution. Real-space mapping of strain distributions in pseudomorphically strained, raised SiGe structures revealed that elastic relaxation extends approximately 20 times the feature thickness from their edges. X-ray topographic methods were also applied to map the substrate deformation induced by overlying SiGe features. A formulation based on the classical Ewald-von Laue theory of dynamical diffraction was derived to match the measured diffraction profiles.

Motivated by recent experiments on the electro-hydrodynamic instability of spin-castpolymer films, we study the undulation instability of a thin viscoelastic polymer filmunder in-plane stress and in the presence of either a close by contactor or an electricfield, both inducing a normal stress on the film surface. We find that the in-plane stressaffects both the typical timescale of the instability and the unstable wavelengths. Thefilm stability is also sensitive to the boundary conditions used at the film-substrateinterface. We have considered two conditions, either rigidly attaching the film to thesubstrate or allowing for slip.

We study molecular motor-induced microtubule self-organization in dilute and semi-dilutefilament solutions. In the dilute case, we use a probabilistic model of microtubuleinteraction via molecular motors to investigate microtubule bundle dynamics. Microtubulesare modeled as polar rods interacting through fully inelastic, binary collisions. Ourmodel indicates that initially disordered systems of interacting rods exhibit anorientational instability resulting in spontaneous ordering. We study the existence anddynamic interaction of microtubule bundles analytically and numerically. Our resultsreveal a long term attraction and coalescing of bundles indicating a clear coarsening inthe system; microtubule bundles concentrate into fewer orientations on a slow logarithmictime scale. In semi-dilute filament solutions, multiple motors can bind a filament toseveral others and, for a critical motor density, induce a transition to an ordered phasewith a nonzero mean orientation. Motors attach to a pair of filaments and walk along thepair bringing them into closer alignment. We develop a spatially homogenous, mean-fieldtheory that explicitly accounts for a force-dependent detachment rate of motors, which inturn affects the mean and the fluctuations of the net force acting on a filament. We showthat the transition to the oriented state can be both continuous and discontinuous whenthe force-dependent detachment of motors is important.

Effective conditioning requires a correlation between the experimenter's definition of a response and an organism's, but an animal's perception of its behavior differs from ours. These experiments explore various definitions of the response, using the slopes of learning curves to infer which comes closest to the organism's definition. The resulting exponentially weighted moving average provides a model of memory that is used to ground a quantitative theory of reinforcement. The theory assumes that: incentives excite behavior and focus the excitement on responses that are contemporaneous in memory. The correlation between the organism's memory and the behavior measured by the experimenter is given by coupling coefficients, which are derived for various schedules of reinforcement. The coupling coefficients for simple schedules may be concatenated to predict the effects of complex schedules. The coefficients are inserted into a generic model of arousal and temporal constraint to predict response rates under any scheduling arrangement. The theory posits a response-indexed decay of memory, not a time-indexed one. It requires that incentives displace memory for the responses that occur before them, and may truncate the representation of the response that brings them about. As a contiguity-weighted correlation model, it bridges opposing views of the reinforcement process. By placing the short-term memory of behavior in so central a role, it provides a behavioral account of a key cognitive process.

Ces descriptions schématiques d'actions de Recherche et Technologie, sont situées dans un parcours collatéral en relation avec les débuts des projets Ariane. Elles ont été conduites à l'aide de groupements interdisciplinaires dont les GdR du CNRS, et comportant des acteurs scientifiques, enseignants-chercheurs, ingénieurs, technologues et industriels. La démarche technologique et industrielle de construction est présentée à l'aide des fonctions techniques en mécanique. L'objet technique est visé, à partir de conditions initiales des objectifs affichés comme projet, par la mise en œuvre des flux d'énergies, de produits, d'acteurs, et d'informations industrielles. Ceci s'associe à la maîtrise du comportement en utilisation effective et à l'utilisation des connaissances exprimées par la recherche et l'enseignement. On incorpore donc au long du déroulé opératoire des repères, lieu de couplages amont/aval et aval/amont.

Time-resolved high-resolution transmission electron microscopy at a spatial resolution of 0.2 nm and a time resolution of 1/60 sec using a piezo-driving specimen holder is reported here. Various types of atomic processes in mechanical interaction, such as contact, bonding, deformation, and fracture, in nanometer-sized gold crystallites and carbon nanotubes are demonstrated.

Two models for the heating responsible for granite generation during convergent deformation may be distinguished on the basis of the length- and time-scales associated with the thermal perturbation, namely: (1) long-lived, lithospheric-scale heating as a conductive response to the deformation, and (2) transient, localised heating as a response to advective heat sources such as mantle-derived melts. The strong temperature dependence of lithospheric rheology implies that the heat advected within rising granites may affect the distribution and rates of deformation within the developing orogen in a way that reflects the thermal regime attendant on granite formation; this contention is supported by numerical models of lithospheric deformation based on the thin-sheet approximation. The model results are compared with geological and isotopic constraints on granite genesis in the southern Adelaide Fold Belt where intrusion spans a 25 Ma convergent deformation cycle, from about 516 to 490 Ma, resulting in crustal thickening to 50–55 km. High-T metamorphism in this belt is spatially restricted to an axis of magmatic activity where the intensity and complexity of deformation is significantly greater, and may have started earlier, than in adjacent low-grade areas. The implication is that granite generation and emplacement is a causative factor in localising deformation, and on the basis of the results of the mechanical models suggests that granite formation occurred in response to localised, transient crustal heating by mantle melts. This is consistent with the Nd- and Sr-isotopic composition of the granites which seems to reflect mixed sources with components derived both from the depleted contemporary mantle and the older crust.