Apache Spark is a popular framework for data analytics with attractive features such as fault tolerance and interoperability with the Hadoop ecosystem. Unfortunately, many analytics operations in Spark are an order of magnitude or more slower compared to native implementations written with high performance computing tools such as MPI. There is a need to bridge the performance gap while retainin...

T he technology for generating and detecting electromagnetic waves has evolved significantly over the last 120 years. In the early 1890s, Guglielmo Marconi used a spark-gap transmitter to build a wireless telegraphy system. In his design, he charged a capacitor to a high dc voltage and connected it to a parallel combination of an inductor, a second capacitor, and an antenna through an air gap. ...

SUMMARY The electromagnetic fields emitted from an electrostatic discharge (ESD) event occurring between charged metals cause seriously damage high-tech equipment. In order to clarify the generation mechanism of such ESD fields and also to reduce them, we previously proposed a finite-difference time-domain (FDTD) algorithm based on a delta-gap feeding method and a frequency dispersion character...

Although the MapReduce programming model has so far been highly successful, not all applications are well suited to this model. Spark bridges this gap by providing seamless support for iterative and interactive jobs that are hard to express using the acyclic data flow model pioneered by MapReduce. While benchmarking Spark, we identified that the default broadcast mechanism implemented in the Sp...

A non-stationary polar gap model first proposed by Ruderman & Sutherland (1975) is modified and applied to spark–associated pulsar emission at radio wavelengths. It is argued that under physical and geometrical conditions prevailing above pulsar polar cap, highly non-stationary spark discharges do not occur at random positions. Instead, sparks should tend to operate in well determined preferred...

Two types of gap phenomena (types I and II ) have been described in human hearts and their electrophysiologic bases have been delineated. In both types of gap phenomena relatively early premature atrial impulses are blocked within some portion of the His-Purkinje system (HPS). By increasing the prematurity of the atrial depolarization, conduction to the ventricles resumes due to delay of the pr...