Geometry-dependent electrostatics near contact lines

Long-ranged electrostatic interactions in electrolytes modify their contact angles on charged substrates in a scale and geometry dependent manner. For angles measured at scales smaller than the typical Debye screening length, the wetting geometry near the contact line must be explicitly considered. Using variational and asymptotic methods, we derive new transcendental equations for the contact angle that depend on the electrostatic potential only at the three phase contact line. Analytic expressions are found in certain limits and compared with predictions for contact angles measured with lower resolution. An estimate for electrostatic contributions to {\it line} tension is also given.Comment: 3 .eps figures, 5p

Hennessy-Milner Logic with Greatest Fixed Points as a Complete Behavioural Specification Theory

There are two fundamentally different approaches to specifying and verifying properties of systems. The logical approach makes use of specifications given as formulae of temporal or modal logics and relies on efficient model checking algorithms; the behavioural approach exploits various equivalence or refinement checking methods, provided the specifications are given in the same formalism as implementations. In this paper we provide translations between the logical formalism of Hennessy-Milner logic with greatest fixed points and the behavioural formalism of disjunctive modal transition systems. We also introduce a new operation of quotient for the above equivalent formalisms, which is adjoint to structural composition and allows synthesis of missing specifications from partial implementations. This is a substantial generalisation of the quotient for deterministic modal transition systems defined in earlier papers

Multicore liquid perfluorocarbon-loaded multimodal nanoparticles for stable ultrasound and ¹⁹ F MRI applied to in vivo cell tracking

Ultrasound is the most commonly used clinical imaging modality. However, in applications requiring cell-labeling, the large size and short active lifetime of ultrasound contrast agents limit their longitudinal use. Here, 100 nm radius, clinically applicable, polymeric nanoparticles containing a liquid perfluorocarbon, which enhance ultrasound contrast during repeated ultrasound imaging over the course of at least 48 h, are described. The perfluorocarbon enables monitoring the nanoparticles with quantitative 19 F magnetic resonance imaging, making these particles effective multimodal imaging agents. Unlike typical core–shell perfluorocarbon-based ultrasound contrast agents, these nanoparticles have an atypical fractal internal structure. The nonvaporizing highly hydrophobic perfluorocarbon forms multiple cores within the polymeric matrix and is, surprisingly, hydrated with water, as determined from small-angle neutron scattering and nuclear magnetic resonance spectroscopy. Finally, the nanoparticles are used to image therapeutic dendritic cells with ultrasound in vivo, as well as with 19 F MRI and fluorescence imaging, demonstrating their potential for long-term in vivo multimodal imaging. </p

Safe sessions of channel actions in Clojure: A tour of the Discourje Project

To simplify shared-memory concurrent programming, in addition to low-level synchronisation primitives, several modern programming languages have started to offer core support for higher-level communication primitives as well, in the guise of message passing through channels. Yet, a growing body of evidence suggests that channel-based programming abstractions for shared memory also have their issues. The Discourje project aims to help programmers cope with message-passing concurrency bugs in Clojure programs, based on run-time verification and dynamic monitoring. The idea is that programmers write not only implementations, but also specifications (of sessions of channel actions). Discourje then offers a library to ensure that implementations run safely relative to specifications (= “bad” channel actions never happen). This paper gives a tour of the current state of Discourje, by example; it is intended to serve both as a general overview for readers who are unfamiliar with previous work on Discourje, and as an introduction to new features for readers who are familiar

Circular Coinduction with Special Contexts

Coinductive proofs of behavioral equivalence often require human ingenuity, in that one is expected to provide a "good" relation extending one's goal with additional lemmas, making automation of coinduction a challenging problem. Since behavioral satisfaction is a 0 2 -hard problem, one can only expect techniques and methods that approximate the behavioral equivalence. Circular coinduction is an automated technique to prove behavioral equivalence by systematically exploring the behaviors of the property to prove: if all behaviors are circular then the property holds. Empirical evidence shows that one of the major reasons for which circular coinduction does not terminate in practice is that the circular behaviors may be guarded by a context. However, not all contexts are safe. This paper proposes a large class of contexts which are safe guards for circular behaviors, called special contexts, and extends circular coinduction appropriately. The resulting technique has been implemented in the CIRC prover and experiments show that the new technique can prove many interesting behavioral properties fully automatically

Circular Coinduction with Special Contexts

Coinductive proofs of behavioral equivalence often require human ingenuity, in that one is expected to provide a "good" relation extending one's goal with additional lemmas, making automation of coinduction a challenging problem. Since behavioral satisfaction is a 0 2 -hard problem, one can only expect techniques and methods that approximate the behavioral equivalence. Circular coinduction is an automated technique to prove behavioral equivalence by systematically exploring the behaviors of the property to prove: if all behaviors are circular then the property holds. Empirical evidence shows that one of the major reasons for which circular coinduction does not terminate in practice is that the circular behaviors may be guarded by a context. However, not all contexts are safe. This paper proposes a large class of contexts which are safe guards for circular behaviors, called special contexts, and extends circular coinduction appropriately. The resulting technique has been implemented in the CIRC prover and experiments show that the new technique can prove many interesting behavioral properties fully automatically