Absolute Timing of the Crab Pulsar with RXTE

We have monitored the phase of the main X-ray pulse of the Crab pulsar with the Rossi X-ray Timing Explorer (RXTE) for almost eight years, since the start of the mission in January 1996. The absolute time of RXTE's clock is sufficiently accurate to allow this phase to be compared directly with the radio profile. Our monitoring observations of the pulsar took place bi-weekly (during the periods when it was at least 30 degrees from the Sun) and we correlated the data with radio timing ephemerides derived from observations made at Jodrell Bank. We have determined the phase of the X-ray main pulse for each observation with a typical error in the individual data points of 50 us. The total ensemble is consistent with a phase that is constant over the monitoring period, with the X-ray pulse leading the radio pulse by 0.0102+/-0.0012 period in phase, or 344+/-40 us in time. The error estimate is dominated by a systematic error of 40 us in the radio data, arising from uncertainties in the variable amount of pulse delay due to interstellar scattering and instrumental calibration. The statistical error is 0.00015 period, or 5 us. The separation of the main pulse and interpulse appears to be unchanging at time scales of a year or less, with an average value of 0.4001+/-0.0002 period. There is no apparent variation in these values with energy over the 2-30 keV range. The lag between the radio and X-ray pulses may be constant in phase (rotational) or constant in time (linear pathlength). We are not (yet) able to distinguish between these two interpretations.Comment: 11 pages, 2 figure

C1− Continuous crack propagation for mixed-mode fracture problems

In this work a C1− continuous crack propagation algorithm is proposed to improve the numerical simulation of localized deformation patterns, using higher order elements. The algorithm is applied for a standard smeared crack model and is validated by a mixed-mode fracture problem. From the results a reduction of mesh-induced directional bias is observed

Khoros software specification format and interoperability

Khoros defines formats for User Interface Specification (UIS) and Program Specification (PS) files. From such files, its code generator, Ghostwriter, creates source files and documentation. The great advantage of the system is that the code fragments that make up part of the PS file are purely generic. All Khoros-related code is created by the code generator; this includes all user interface code. As a matter of fact, both specification files are very generic in nature. Thus, one could imagine using it as the basis for other software systems. A case is made that writing a code generator that would create IRAF-compatible code from the Khoros UIS and PS files is fairly trivial. Another aspect of the Khoros system conventions concerns the way execution commands are generated by the user interface and the actual syntax of those commands. The protocols are such that interoperability at the level of executable modules is readily possible

A structured data transfer protocol

The transfer of data between different computers and programs can be a major obstacle during data analysis. We present a new data transfer protocol which is based on a simple structure containing a value, an error, and a unit. Each of these members can be arrays or another structure. The ability to nest structures allows for the concept of objects. When using an object-oriented language such as C++, reference can be made to the object name instead of each element explicitly. Prototype code has been written which implements the basic design with enhancements planned for the future

Advances of epigenetic editing

Epigenetic editing refers to the locus-specific targeting of epigenetic enzymes to rewrite the local epigenetic landscape of an endogenous genomic site, often with the aim of transcriptional reprogramming. Implementing clustered regularly interspaced short palindromic repeat-dCas9 greatly accelerated the advancement of epigenetic editing, yielding preclinical therapeutic successes using a variety of epigenetic enzymes. ,CRISPR/dCas9 Here, were review the current applications of these epigenetic editing tools in mammalians and shed light on biochemical improvements that facilitate versatile applications

Modeling the Structural Response of Reinforced Glass Beams using an SLA Scheme

This paper investigates whether a novel computational sequentially linear analysis(SLA) technique, which is especially developed for modeling brittle materialresponse, is applicable for modeling the structural response of metal reinforcedglass beams. To do so, computational SLA results are compared with experimentalresults of four-point bending tests. The results show similarities in loaddisplacementcurves and to some extent also in cracking behaviour. Overall, it isconcluded that the SLA scheme is a very promising technique to model thestructural response of reinforced glass beams, which will be even further improvedin future research

Chemical enrichment of the complex hot ISM of the Antennae galaxies: I. Spatial and spectral analysis of the diffuse X-ray emission

We present an analysis of the properties of the hot interstellar medium (ISM) in the merging pair of galaxies known as The Antennae (NGC 4038/39), performed using the deep, coadded ~411 ks Chandra ACIS-S data set. These deep X-ray observations and Chandra's high angular resolution allow us to investigate the properties of the hot ISM with unprecedented spatial and spectral resolution. Through a spatially resolved spectral analysis, we find a variety of temperatures (from 0.2 to 0.7 keV) and Nh (from Galactic to 2x10^21 cm^-2). Metal abundances for Ne, Mg, Si, and Fe vary dramatically throughout the ISM from sub-solar values (~0.2) up to several times solar.Comment: 33 pages, 18 figures, revised version accepted by Astrophysical Journal Supplement Serie