Verifying programs by induction on their data structure: General format and applications

As a static object, a program presents two axes of complexity: the control structure and the data structure. The invariant assertion method is used to prove programs by induction on their control structure: The correctness of complex control structures is deduced from the correctness of their components, which are, in some sense, simpler. Orthogonally, one may want to prove programs by induction on their data structure: the correctness of the program on complex data items is deduced from its correctness on simpler data items. A general theorem of correctness by induction on the data structure is given. This theorem is applied with two distinct definitions of complexity (i.e., two distinct ordering relations on the space of the program) yielding, respectively, the subgoal induction method and the intermittent assertion method.     

Computation of time-domain response of URC networks

Computer-simulation results of the evaluation of the step response of uniformly distributed RC networks (URC networks) are presented, using Liou's procedure. The advantages of using the procedure include obviating the finding of poles of the transfer function and ease of accommodating boundary conditions, as well as good numerical control.     

Sinus aspergillosis after an endodontic treatment. Presentation of a clinical case

Aspergillosis is an opportunistic deep mycosis that occurs in immunocompromised patients, often in the paranasal sinuses. However, it sometimes occurs in healthy subjects, producing symptoms similar to those of a chronic sinusitis that is unresponsive to conventional treatment. A possible entry point for Aspergillus is the oroantral communication originated by perforation of the dental root cavity during root canal of a molar with penetration of material. We report the clinical case of a patient with symptoms of chronic sinusitis who was diagnosed as sinus aspergillosis after radiological and histological study. The origin may have been a third upper molar in which a root canal was performed.     

Stressed Skin Design Versus Braced Frame Design Through Efficient Numerical Modelling

International Journal of Steel Structures - Steel frame structures are traditionally designed with bracings that stabilize the main bearing structure. Another approach is to apply the...     

New access modes of parallel memory subsystem for sub-pixel motion estimation

Accessing pixels in memory is a well-known bottleneck of SIMD (single instruction multiple data) processors in video/imaging. To tackle it, we propose new block and row access modes of parallel on-chip memory subsystem, which enable a higher processing throughput and lower energy consumption than the access modes of the state-of-the-art subsystems. The new access modes significantly reduce the number of on-chip memory accesses, and thereby accelerate one of key video/imaging kernels: sub-pixel block-matching motion estimation. The main idea is to exploit spatial overlaps of blocks/rows accessed for pixel interpolation, which are known at the subsystem design-time, and merge multiple accesses into a single one by accessing somewhat more pixels at a time than with other parallel memories. To avoid the need for a wider, and, therefore, more costly SIMD datapath, we propose new memory read operations that split all pixels accessed at a time into multiple SIMD-wide blocks/rows, in a convenient way for further processing. As a proof of concept, we describe a parametric, scalable, and cost-efficient architecture that supports the new access modes. The architecture is based on a previously proposed set of memory banks with multiple pixels per bank word, and a previously proposed shifted scheme for arranging pixels in the banks. We analytically and experimentally demonstrate advantages of this work on a case study of sub-pixel motion estimation for video frame-rate conversion. The implemented motion estimator processes 2160p video at 60 fps in real time, while clocked at 600 MHz. Compared to the implementations based on the state-of-the-art subsystems, this work enables 40–70 % higher throughput, consumes 17–44 % less energy and has similar silicon area and off-chip memory bandwidth costs. That is 1.8–2.9 times more efficient than the prior art, considering the throughput and all costs, i.e., consumption, area, and off-chip bandwidth. Such a higher efficiency is the result of the new access modes, which reduced the number of on-chip memory accesses by 1.6–2.1 times, and the cost-efficient architecture.     

Cross Pharmacological,Biochemical and Computational Studies of a Human Kv3.1b Inhibitor from Androctonus australis Venom

The voltage-gated K⁺ channels Kv3.1 display fast activation and deactivation kinetics and are known to have a crucial contribution to the fast-spiking phenotype of certain neurons. AahG50, as a natural product extracted from Androctonus australis hector venom, inhibits selectively Kv3.1 channels. In the present study, we focused on the biochemical and pharmacological characterization of the component in AahG50 scorpion venom that potently and selectively blocks the Kv3.1 channels. We used a combined optimization through advanced biochemical purification and patch-clamp screening steps to characterize the peptide in AahG50 active on Kv3.1 channels. We described the inhibitory effect of a toxin on Kv3.1 unitary current in black lipid bilayers. In silico, docking experiments are used to study the molecular details of the binding. We identified the first scorpion venom peptide inhibiting Kv3.1 current at 170 nM. This toxin is the alpha-KTx 15.1, which occludes the Kv3.1 channel pore by means of the lysine 27 lateral chain. This study highlights, for the first time, the modulation of the Kv3.1 by alpha-KTx 15.1, which could be an interesting starting compound for developing therapeutic biomolecules against Kv3.1-associated diseases.     

Gold nanocluster distribution on faceted and kinked Si nanowires

Si nanowires were grown on (111) substrates by ultra high vacuum chemical vapor deposition using the Au-catalyzed vapor-liquid-solid (VLS) technique. Depending on the growth temperature, the nanowires can be straight in the <111> direction or kinked towards <112>. We present a transmission electron microscopy investigation of the <112> Si nanowires. Results exhibit the relationship between the morphology of nanowires and the distribution of gold on sidewalls bounding the nanowires. The distribution of Au nanoclusters is used as a probe to investigate the growth mechanisms of the VLS process. Our observations are consistent with the model of nucleation and step flow related to the oscillatory behavior of the catalyst droplet.