Multiple Contact Points Research Articles

Results of locking compression plate in the management of fracture distal end of femur in adults

Introduction: The use of locking compression plate in fractures of distal femur in our study seems to be associated with a good functional outcome and early recovery. The DF-LCP is a good implant to use for fractures of the distal femur particularly intra-articular type and osteoporotic fractures. Recent advances in technology for treatment of fractures distal end femur with locking compression plate become popular and has clear biomechanical advantages when compared with conventional plating and other method of fixation. When combined with minimally invasive surgical techniques, locking compression plate may cause substantially less iatrogenic tissue damage when compared with conventional plating. Locking compression plates offers multiple points of fixed-angle contact between the plate and screws, theoretically reducing the tendency for varus collapse that is seen with traditional lateral plates. The commonly observed complications of fracture distal end of femur are knee stiffness, implant failure and loss of reduction are minimal with it. Surgical exposure for plate placement requires significantly less periosteal stripping and soft tissue exposure than that of normal plates. Materials and Methods: This prospective study was conducted which included 30 patients with fracture distal end of femur (Extra & intra articular type A and C based on AO classification) treated with open reduction and internal fixation with distal femoral locking compression plate (DF-LCP) between November 2011 to October 2013 at in the department of orthopaedics, Govt. Medical college & associated MBS hospital, Kota and followed-up for a minimum period of 6 months. The patient’s ages ranged from 18 to 78 with a mean of 42 years. The duration of follow up ranged from 6 months to 21 months. The clinical assessment was conducted at least 6 months post-operatively using the Schatzker & Lambert scoring system. Results: Result showed that 9 patients had excellent results, 17 good, 2 fair and 2 failures. Conclusion: The use of locking compression plate in fractures of distal femur in our study seems to be associated with a good functional outcome and early recovery and is a good implant to use for fractures of the distal femur particularly intra-articular type and osteoporotic fractures.

Personal Resilience as a Predictor of Professional Development Engagement and Career Satisfaction of Agriscience Teachers

The profession of teaching is inherently stressful. Resilience, or the ability to adapt and develop competence despite exposure to disruptive change, has been shown to be beneficial for teachers. The purpose of this study was to determine if personal resilience is a predictor of professional development engagement and career satisfaction of agriscience teachers. A census of agriscience teachers in four purposefully selected states was taken. Data were collected using the TailoredDesign Method, using multiple points of contact with multiple modes to minimize survey error. The overall response rate was 72.5% (n = 892). The linear combination of independent variables in a stepwise backwards regression model explained 13.7% of the variance of professional development engagement and 21.4% of the variance of career satisfaction. These findings suggested that increasing the resilience of agriscience teachers, specifically in the areas of positive: world and focused, could lead to increased engagement in professional development and career satisfaction, which has been shown to be a factor that increases teacher efficacy. Additional research is needed to explore how to increase the resilience of agriscience teachers and the relationship between teacher resilience and student outcome variables.

Zeno chattering of rigid bodies with multiple point contacts

Ideally rigid objects establish sustained contact with one another via complete chatter (a.k.a. Zeno behavior), i.e. an infinite sequence of collisions accumulating in finite time. Alternatively, such systems may also exhibit a finite sequence of collisions followed by separation (sometimes called incomplete chatter). Earlier works concerning the chattering of slender rods in two dimensions determined the exact range of model parameters, where complete chatter is possible. We revisit and slightly extend these results. Then the bulk of the paper examines the chattering of three-dimensional objects with multiple points hitting an immobile plane almost simultaneously. In contrast to rods, the motion of these systems is complex, nonlinear, and sensitive to initial conditions and model parameters due to the possibility of various impact sequences. These difficulties explain why we model this phenomenon as a nondeterministic discrete dynamical system. We simplify the analysis by assuming linearized kinematics, frictionless interaction, by neglecting the effect of external forces, and by investigating objects with rotational symmetry. Application and extension of the theory of common invariant cones of multiple linear operators enable us to find sufficient conditions of the existence of initial conditions, which give rise to complete chatter. Additional analytical and numerical investigations predict that our sufficient conditions are indeed exact, moreover solving a simple eigenvalue problem appears to be enough to judge the possibility of complete chatter. \keywords{contact dynamics \and chattering \and Zeno behavior \and common invariant cone

A Compact Single-Cantilever Multicontact RF-MEMS Switch With Enhanced Reliability

This letter presents a novel cantilever and electrode biasing design of a metal-contact radio frequency microelectromechanical systems (RF-MEMS) switch to integrate multiple contact points in a single cantilever to improve the reliability of the switch. In the design presented in this letter, multiple contact points are integrated in a single cantilever. The contact points are used to conduct RF current one by one until one point fails. To switch between the contact points, two actuator electrodes are placed under the cantilever and biased with different voltages and the touching point between the cantilever and bottom RF electrode are changed. The parasitic capacitance of the switch is kept to be the same with that of a single contact point RF-MEMS switch. The OFF-state isolation will not be worsen, while accumulation of the lifetime of each contact point can improve the overall lifetime of the switch. Without the need of shrinking the actuator to maintain small parasitics capacitance, the contact force is also not sacrificed when comparing to the case of putting several miniature switches together. The performance and reliability improvement of the switch are experimentally demonstrated. The insertion losses of the switch of different contact points are <1 dB, and the isolation is better than 10 dB up to 20 GHz.

Transitions and singularities during slip motion of rigid bodies

The dynamics of moving solids with unilateral contacts are often modelled by assuming rigidity, point contacts, and Coulomb friction. The canonical example of a rigid rod with one endpoint slipping in two dimensions along a fixed surface (sometimes referred to as Painlevé rod) has been investigated thoroughly by many authors. The generic transitions of that system include three classical transitions (slip-stick, slip reversal, and liftoff) as well as a singularity called dynamic jamming, i.e., convergence to a codimension 2 manifold in state space, where rigid body theory breaks down. The goal of this paper is to identify similar singularities arising in systems with multiple point contacts, and in a broader setting to make initial steps towards a comprehensive list of generic transitions from slip motion to other types of dynamics. We show that – in addition to the classical transitions – dynamic jamming remains a generic phenomenon. We also find new forms of singularity and solution indeterminacy, as well as generic routes from sliding to self-excited microscopic or macroscopic oscillations.

Bioinspired sutured materials for strength and toughness: Pullout mechanisms and geometric enrichments

Hard structural elements in nature are often joined with sutures lines, as seen in human skull, cephalopods or turtle shell. These sutures can arrest cracks, and can provide flexibility for respiration, locomotion or growth. In this paper we introduce a morphometric method to capture the complex shape of sutured interfaces using only a few parameters. The method is simple, and can capture relatively complex suture geometries with re-entrants, interlocking features. The study starts with a simple jigsaw-like model which is enriched with additional features (plateau regions in dovetail-like sutures, multiple locking sites). For each case, closed form and finite elements solutions are developed to capture the full nonlinear pullout response and to predict the maximum stress (and potential fracture) in the solid material. These models were then used to identify the geometries and interface properties (friction) that lead to optimum combinations of strength and energy absorption. Suture designs that reduced frictional stress with low coefficient of friction or with multiple contact points were the most efficient. The results can serve as guidelines to design and optimization of non-adhesive sutures with arbitrary shapes made of arc of circles and lines. We found that the best designs involve low coefficient of friction, which raises an interesting hypothesis on the function of the protein layer in natural sutured lines: This soft layer could act as “lubricant” to prevent the fracture of the solid structures.

Jerónima's Divided Self: Role-play in El amor médico

Jerónima's Divided Self:Role-play in El amor médico Robert L. Turner III El amor médico is a self-contradictory play about a self-contradictory dama that simultaneously promotes Jerónima's independence and mocks her behavior. On one hand, Jerónima proves to the world that she is an intelligent and independent woman whose learning is the equal to that of any man. On the other, Jerónima chooses to marry a man whom she has only fitfully chased and in marrying him, relinquishes her freedom. The tension between her desire for autonomy and her love of Gaspar is emblematic of the internal division she embodies. Historically, this text has lacked attention. Little scholarship exists on El amor médico, and what scholarship there is tends towards either comparative, historical, or reception studies. For example, Yvonne David-Peyre discusses Tirso's use of medical texts and his medical knowledge while in "Del vergonzoso en palacio a El amor médico: El camino hacia la ironía de Tirso de Molina frente a Lope de Vega," and "Tirso contra Lope: Imitación irónica de La portuguesa y Dicha del amor forastero en El amor médico" Elvezio Canónica argues that both El vergonzoso en palacio and El amor médico have multiple points of contact with Lope's La portuguesa y Dicha del amor forastero. Blanca Oteiza explores how this play was presented and received in the nineteenth century and Ruth Kennedy deals with the historical aspects of the text, but not its literary content. Likewise, a recent article by Henry Sullivan and Luciana de Cunha Monteiro delves deeply into Tirso's family tree and Portuguese connections, but only touches upon the text lightly. These articles exemplify the common tone of the research dedicated to the play. Much of the remaining criticism focuses on the debate surrounding the date of the play's composition. The earliest extant version of the play comes from the Cuarta parte de las comedias del maestro Tirso de Molina in 1635 (Bushee 93); there is no manuscript copy. There are several proposed composition dates, including 1619 (Oteiza 23–29), 1621 (Blanca de los Ríos in Obras dramáticas completas 961), and 1625–26 (Kennedy 11–33). Some few studies address the theme of cross-dressing and disguise. Henry Sullivan's, "Tirso de Molina: Dramaturgo andrógino," is an exploration of lesbian tendencies in the play, where he argues that Jerónima's use of cross-dressing can be read as the manifestation of her inclinations. In Robert Ter Horst's "Aspects of Love and Learning in El amor médico," he presents the play as a confirmation of feminine rights, asserting, "The feminism of El [End Page 2] amor médico is authentic; it is profound" (297). With the article, "Do Clothes Make the Man?" Anita K. Stoll addresses the use of disguise in this play, as well as in Don Gil de las calzas verdes, and La celosa de sí misma. The article begins and ends with a Lacanian reading (through Stroud) of cross-dressing from a gendered perspective, in which Stoll discusses the use of disguise, with cross-dressing presented as a secondary element. Later in "Cross-dressing in Tirso's El amor médico [Love, the Doctor] and El Aquiles [Achilles]," Stoll uses this text, in conjunction with El Aquiles, to discuss the arbitrary nature of gender as a societal and personal construction. The most detailed analysis of the text in the last few decades belongs to Melveena McKendrick, in her 1974 monograph Woman and Society in the Spanish Drama of the Golden Age: A Study of the Mujer Varonil. McKendrick views Jerónima's actions in feminist terms, while explicitly rejecting a sexualized reading (316). She bases her views on the assertiveness of Jerónima's character and active pursuit of her goal. "[L]ike so many of Tirso's heroines, she translates her desires into immediate action" (236). This text laid the ground for much of the criticism that followed and for the purposes of this article, McKendrick's reading is still the most pertinent, since I wish to examine how the use...

Arte e Psicologia em Vergílio Ferreira

In this article, we select the thoughts that Vergilio Ferreira had about Psychology, especially in his essay work, with a particular focus, but not exclusively, in his first book of essays, from 1957, Do Mundo Original. From his critical view on this science, we will try to reveal how, some decades later, the third wave of behavioral and cognitive therapies make similar criticisms and try to respond to these. Finally, we will also try to show the multiple points of contact between some of those therapies, namely with Acceptance and Commitment Therapy and Mindfulness based therapies, and the idea of experiencing Art, defended by Vergilio Ferreira as an alternative to the psychological vision of the human being, aiming at his full realization.

Non-peptide CRF-Receptor Antagonists: Allosterism, Kinetics and Translation to Efficacy in Human Disease.

G-Protein coupled receptors (GPCRs) have been, and remain a key target of drug discovery programs for human disease. While many drugs have been developed that interact with these proteins in the simple classic manner - that is - physically blocking the cognate ligand from simply binding to its target receptor, drug discovery approaches have elucidated alternative more complex methods by which small molecules can interact with these receptors and block their function. This is most evident in the Class B GPCRs where the cognate ligands are relatively large peptides with multiple points of contact on the GPCR spanning both hydrophilic and hydrophobic domains on the same protein to elicit function. It has therefore been difficult to precisely determine not only the mechanism by which a small molecule can inhibit the function of a large peptide but also the nature of that mechanism that drives the differences in efficacy. This review will examine in detail the nature of small molecule inhibition of corticotropin-releasing factor receptors and illustrate the role that allosteric binding and kinetics play in the functional inhibition of this Class B GPCR.

Feasibility of using a video diary methodology with older African Americans living alone

Objectives The goal of this research was to determine whether video diary, a qualitative, self-recorded, video-ethnographic method, is feasible for use among older African Americans (AAs) who live alone. The research, which stems from a larger study on aging in place, focuses specifically on the pros and cons of the video diary and provides recommendations for improving the methodology. Methods Twelve participants were engaged in a 90-minute training on how to record videos using tablet computers, seven days of recording video diaries, and one in-person interview. Results While all participants reported being comfortable with using tablet computers to record video diaries, many participants expressed the need for additional training and assistance. In addition, video diaries recorded by participants commonly exhibited issues (e.g. framing, gaze, and audibility) that compromised video quality. Discussion Video diary may be an effective method for collecting information from older African Americans. However, some suggestions for improving this methodology are providing in-depth video diary and additional camera training, establishing multiple points of contact for technical support, and providing male participants with additional practice.

Oxidation−Stable Plasmonic Copper Nanoparticles in Photocatalytic TiO2 Nanoarchitectures

We describe the incorporation of plasmonic copper (Cu) nanoparticles into titania (TiO2) aerogels and demonstrate surface plasmon resonance (SPR)–driven photoelectrochemical oxidation of methanol under visible light. Copper could provide a more abundant, less expensive alternative to gold and silver as a visible light–active plasmonic metal, however, the propensity of Cu to oxidize at the expense of its plasmonic character greatly limits its potential applications. Most reports of supported, plasmonic Cu nanoparticles describe the necessity of preventing Cu oxidation by maintaining strictly anoxic environments or relying on surface-obscuring chemical stabilizers. We stabilize plasmonic Cu nanoparticles by establishing extensive interfacial contact between Cu nanoparticles and a TiO2 aerogel support. The multiple points of contact between 2–3 nm Cu nanoparticles photodeposited at the networked ~10 nm TiO2 particulates of the aerogel stabilizes Cu against oxidation to an extent that preserves the plasmonic behavior of the nanoparticles, even after long-term exposure to ambient air. The wavelength dependence of photoelectrochemical methanol oxidation at Cu/TiO2 aerogel photoanodes verifies the plasmonic origin of the photoelectrochemistry. Plasmonic behavior is not seen for Cu photodeposited at a commercially available, non-networked TiO2 nanopowder in which the primary particle size is ~10× greater than the size of the supported Cu particle. The divergent behavior of Cu when a 3D Cu||oxide interface is formed on aerogel supports compared to the 1D junction between Cu on commercial TiO2 nanopowder supports highlights the importance of the interfacial design motif on preserving plasmonic Cu.

Flow behavior analysis of two-phase (gas/water) flowback and early-time production from hydraulically-fractured shale gas wells using a hybrid numerical/analytical model

In recent years, quantitative analysis of flowback and early-time production data for interpretation of hydraulic fracture properties in shale has received significant attention. With high-resolution phase rates and flowing pressures, analysis of flowback and early-time production data provides an early opportunity to determine key parameters for well performance forecasting. The main purpose of this paper is to quantify flow characteristics associated with two-phase flowback and early-time production of shale gas wells exhibiting both planar fractures and a complex fracture network using a rigorous and efficient flow model.To study flow characteristics of this complex system, a hybrid numerical/analytical model is developed in which matrix and hydraulic fracture flow is accounted for. The finite-difference method is used to numerically model unsteady-state two-phase fracture flow. The analytical matrix flow model, derived using the line-source function, is dynamically coupled with the fracture flow model by imposing continuity of pressure and flux on the fracture surface. The main advantage of the hybrid solution over more conventional numerical simulation is reduced model setup and run time, without loss of the important physics.Detailed flow regime analysis reveals that the gas/water flowback and early-production of a horizontal well with a planar fracture geometry may the following complex sequence of flow-regime: 1) radial flow of water in the fracture; 2) a first transient linear flow of water in the fracture; 3) a second transient linear flow of water in the fracture; 4) boundary-dominated flow of water in the fracture and gas linear flow in matrix. Water primarily depletes in the first three flow periods. Development of the water boundary-dominated flow and gas linear flow indicates the system indicate that the system is at the end of flowback period and proceeds early-time production. Specially, the second water linear flow period develops when both gas and water production are dominating the system, and is caused by the pressure maintenance associated with gas flux from matrix. A complex fracture network with the same total fracture length as a planar fracture system will exhibit the same sequence of flow regimes. Due to the accelerated water drainage caused by multiple contact points between fractures and the wellbore in complex fracture network, the system also exhibits a shortened second water transient linear flow period and earlier water boundary-dominated flow.Finally, the new model is also applied to match flowback data obtained from a multi-fractured horizontal well completed in the Marcellus Shale. The results demonstrate the practical application of the new model for deriving reservoir/fracture properties from flowback data and for forecasting.

Enhanced Adhesion of Mosquitoes to Rough Surfaces.

Insects and small animals capable of adhering reversibly to a variety of surfaces employ the unique design of the distal part of their legs. In the case of mosquitoes, their feet are composed of thousands of micro- and nanoscale protruding structures, which impart superhydrophobic properties. Previous research has shown that the superhydrophobic nature of the feet allows mosquitoes to land on water, which is necessary for their reproduction cycle. Here, we show that van der Waals interactions are the main adhesion mechanism employed by mosquitoes to adhere to various surfaces. We further demonstrate that the judicious creation of surface roughness on an opposing surface can increase the adhesion strength because of the increased number of surface elements interacting with the setae through multiple contact points. Although van der Waals forces are shown to be the predominant mechanism by which mosquitoes adhere to surfaces, capillary forces can also contribute to the total adhesion force when the opposing surface is hydrophilic and under humid conditions. These fundamental properties can potentially be applied in the development of superior Long Lasting Insecticidal Nets (LLINs), which represent one of the most effective methods to mitigate mosquito-transmitted infectious diseases such as Malaria, Filaria, Zika, and Dengue.

A General Friction Model of Discrete Interactions for Tendon Actuated Dexterous Manipulators

Continuum robots present the great dexterity and compliance as dexterous manipulators to accomplish complex positioning tasks in confined anatomy during minimally invasive surgery. Tendon actuation is one of the most popular approaches, which is to insert the tendon to eccentrically go through and interact with the flexible backbone to accomplish compliant bends. However, hysteresis of tip trajectory of tendon actuated dexterous manipulators (TA–DMs) has been observed during the loading and unloading procedure, which is mainly caused by the hindered friction at discrete interactions between the actuation tendon and conduits. This paper aims to propose a general friction model to describe the interactions and friction profile at the multiple discrete contact points for tendon actuated dexterous manipulators under the history-dependent tendon tension. The friction model was integrated into the beam theory to describe the hysteresis and loading history-dependent behavior by solving the profiles of tendon force, normal force, and friction force, as well as the deflection of the dexterous manipulator. Experiments were carried out to validate the effectiveness of the proposed friction model. Results indicate that the friction model can successfully describe the discrete interaction and predict the deflection of dexterous manipulator subject to the different tendon loading histories. Furthermore, the effects of discrete friction to the tendon force propagation and the loading history-dependent behavior are discussed.

Contribution of Nano- to Microscale Roughness to Heterogeneity: Closing the Gap between Unfavorable and Favorable Colloid Attachment Conditions.

Surface roughness has been reported to both increase as well as decrease colloid retention. In order to better understand the boundaries within which roughness operates, attachment of a range of colloid sizes to glass with three levels of roughness was examined under both favorable (energy barrier absent) and unfavorable (energy barrier present) conditions in an impinging jet system. Smooth glass was found to provide the upper and lower bounds for attachment under favorable and unfavorable conditions, respectively. Surface roughness decreased, or even eliminated, the gap between favorable and unfavorable attachment and did so by two mechanisms: (1) under favorable conditions attachment decreased via increased hydrodynamic slip length and reduced attraction and (2) under unfavorable conditions attachment increased via reduced colloid-collector repulsion (reduced radius of curvature) and increased attraction (multiple points of contact, and possibly increased surface charge heterogeneity). Absence of a gap where these forces most strongly operate for smaller (<200 nm) and larger (>2 μm) colloids was observed and discussed. These observations elucidate the role of roughness in colloid attachment under both favorable and unfavorable conditions.

Awareness of Paid Sick Leave among New York City Restaurant Workers.

Restaurant workers are less likely to have paid sick leave (PSL) benefits than other professions, despite the fact that they handle food and interact with the public. In this study, we collected and analyzed quantitative and qualitative data on PSL awareness among New York City's restaurant workers and the factors that produced these levels of awareness. We found that 62% of surveyed workers were aware of NYC's law, and that successful outreach requires building broad awareness and ensuring trustworthy sources of information with multiple points of contact. Our research also highlights the importance of immigrant populations in PSL outreach.

Philosophy's Folds: Seneca, Cavarero, and the History of Rectitude

This article takes as its stimulus Adriana Cavarero's recent investigation of the postures of rectitude and inclination in the Western philosophical tradition (Cavarero 2013). To showcase how this book might catalyze productive interactions between feminist critics in different areas of the humanities, I will bring Cavarero into dialogue with a thinker she mentions in passing who extensively develops “rectitude as a general principle” (Veyne 2003): Seneca. I argue that a gendered ontology of rectitude is increasingly put under pressure and transformed in Seneca'sEpistles, and propose that the letters are a laboratory for developing a new model of inclination that arises from an urgent need to confront the consequences of political impotence and threats to bodily integrity for Roman aristocratic manhood in the 60sce. The playful, densely literaryEpistlesoffer multiple points of contact with Cavarero's own philosophical strategies, and emerge as a highly stimulating text for feminist thinkers interested in the ethical and political implications of acknowledging vulnerability. Reading Seneca alongside Cavarero reminds us that such investigations have a (tortuous, buried) history in Roman antiquity whose recovery is itself politically significant.

The Emergent Field of Organizational Frontlines

Advances in frontline interface technologies and devices are profoundly disrupting how organizations and customers interact to create and exchange value. Where once customer interactions were limited in variety, multiplicity, and complexity, today’s broadband Internet and wireless connection technologies defy limitations to enable organization-customer interactions of ever-increasing diversity and consistency across multiple points of customer contact. No longer are the frontlines inert backgrounds for organizational action involving customers; rather, they are evolving as sites of vibrant innovations and interventions that engage customers, enhance customer experiences, and motivate value (co)creation. To anchor this emergent field, we define organizational frontlines at the intersection of interfaces and interactions that connect organizations and their customers. We historically trace the use of “organizational frontlines” from its initial application in military and management domains through its current and proposed position in both academic and practitioner contexts. We illustrate our definition to highlight research opportunities and underscore the strategic implications for effectively managing organizational frontlines to secure competitive advantage. We conclude with a discussion of special issue articles and the exciting agenda they collectively engage.

Bibliotherapy as a Bullying and Aggressive Behavior Intervention in Schools

Background: Bullying and aggressive behavior continue to create concern across communities as well as for parents, students and faculty within schools. Bullying routinely impacts children and youth. Many social sciences, education, and healthcare groups are interested in developing a standard definition for bullying and aggressive behavior and means to interrupt and change patterns. The purpose of the paper is to recommend a universal strategy to address bullying and aggressive behavior. Methods: A review of the literature indicates universal school-based interventions are effective in reducing the type and level of bullying and aggressive behavior. Bibliotherapy can be considered a universal school-based intervention. Results: Bibliotherapy has been utilized to modify patterns of behavior for the past 40 years. Bibliotherapy has been recommended as an effective means of transforming poor family dynamic, negative individual perception of self, addictive and destructive patterns of behavior, and conflict within community settings. In addition, bibliotherapy has been successful in altering the behavior of both bullies and victims. Therefore, bibliotherapy is recommended as a universal strategy in the elementary school setting. Conclusions: Universal school-based interventions are effective. While there are many interventions that include the youth, families, communities, and schools to address the issue of bullying and victimization, bibliotherapy is ideal. The book series allows the child or youth to develop better skills at social interaction, effective problem-solving and empathy for others. Strategies and interventions that bring multiple points of contact to the child are more effective than a single strategy, such as punishing the bully. It is important for all involved in bullying activities, whether the instigator, the victim, or the observer to learn together how to function as a social group.

Multi-contact haptic exploration and grasping with tactile sensors

Haptic exploration has received a great deal of attention of late thanks to the variety of commercially available tactile sensors. While the majority of previous works consider control of a single contact point at a time, we tackle simultaneous control of multiple contact points on several links. In addition, we use information from the existing tactile signals to increase the number of points in contact. We demonstrate the usefulness of this form of control to speed up exploration, scanning and to compliantly grasp unknown objects. Our controller requires to know only the parts of the robot on which it is desirable to make contact and does not need a model of the environment besides the robot itself. We validate the algorithm in a set of experiments using a robotic hand covered with tactile sensors and arm. In a grasping application, the active adaptation of the fingers to the shape of the object ensures that the hand encloses the object with multiple contact points. We show that this improves the robustness of the grasp compared to simple enclosing strategies. When combined with an exploration strategy, our multi-contact approach offers an efficient use of tactile sensors on the whole surface of robotic fingers, and enables the robot to perform a rapid exploration of complex, non convex shapes while maintaining low contact forces. It is robust to variation in the approach angle and to changes in the geometry and orientation of the object.