Context. PKS 1510-089 is one of only a few flat spectrum radio quasars detected in the VHE (very-high-energy, > 100 GeV) gamma-ray band. Aims. We study the broadband spectral and temporal properties of the PKS 1510-089 emission during a high gamma-ray state. Methods. We performed VHE gamma-ray observations of PKS 1510-089 with the MAGIC telescopes during a long high gamma-ray state in May 2015. In order to perform broadband modelling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state. Results. PKS 1510-089 has been detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, due to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to the ones obtained during previous measurements of the source. The observed flux variability sets for the first time constraints on the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.

This paper presents the first formal analysis of the official memory consistency model for the NVIDIA PTX virtual ISA. Like other GPU memory models, the PTX memory model is weakly ordered but provides scoped synchronization primitives that enable GPU program threads to communicate through memory. However, unlike some competing GPU memory models, PTX does not require data race freedom, and this results in PTX using a fundamentally different (and more complicated) set of rules in its memory model. As such, PTX has a clear need for a rigorous and reliable memory model testing and analysis infrastructure. We break our formal analysis of the PTX memory model into multiple steps that collectively demonstrate its rigor and validity. First, we adapt the English language specification from the public PTX documentation into a formal axiomatic model. Second, we derive an up-to-date presentation of an OpenCL-like scoped C++ model and develop a mapping from the synchronization primitives of that scoped C++ model onto PTX. Third, we use the Alloy relational modeling tool to empirically test the correctness of the mapping. Finally, we compile the model and mapping into Coq and build a full machine-checked proof that the mapping is sound for programs of any size. Our analysis demonstrates that in spite of issues in previous generations, the new NVIDIA PTX memory model is suitable as a sound compilation target for GPU programming languages such as CUDA. CCS Concepts • Hardware → Theorem proving and SAT solving; • Software and its engineering → Consistency.

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We present AHIR, an intermediate representation (IR), that acts as a transition layer between software compilation and hardware synthesis. Such a transition layer is intended to take advantage of optimisations available in the software compiler flow, and also to provide freedom to the low-level synthesiser, to explore options for application-specific implementations. Two operations become possible -reuse of computational resources across different modules in the design, and generation of an application-specific memory subsystem for faster data accesses.AHIR presents a decoupled view of the program, in terms of control flow, data flow and memory accesses. Each module in AHIR is a triplet consisting of a control-path, datapath and a symbolic association between the two. Memory is represented only by load-store operators, while the memory subsystem is separately designed by the implementor.In the program-to-hardware flow, a module in AHIR corresponds to a function in C. A complete program is a callgraph of functions, which is translated to a set of modules. The call-graph is restricted to be a DAG; recursion is not allowed. The representation is generated by a back-end in the software compiler, which runs after all source-level optimisations have been performed by relevant passes.

Abstract-Several solutions exist to bridge the last-mile gap in rural telecom. These extend a point of presence from a town to kiosks in surrounding villages. In this paper, we deal with extending teleconnectivity from these kiosks to various points inside the village. Since laying additional PSTN lines is expensive, we use a single PSTN line connected to a software exchange, and VoIP calls are carried over Ethernet or WiFi. We use soft-phones on computing devices or analog phones with adapters to make or receive calls from different parts of the village. As proofof-concept, we deploy the proposed solution in a rural test-bed and report our experience.