Measuring the upset of CMOS and TTL due to HPM-signals

To measure the performance of electronic components when stressed by High Power Microwave signals a setup was designed and tested which allows a well-defined voltage signal to enter the component during normal operation, and to discriminate its effect on the component.</p><p style=&quot;line-height: 20px;&quot;> The microwave signal is fed to the outside conductor of a coaxial cable and couples into the inner signal line connected to the device under test (DUT). The disturbing HF-signal is transferred almost independent from frequency to maintain the pulse shape in the time domain. The configuration designed to perform a TEM-coupling within a 50 Ohm system prevents the secondary system from feeding back to the primary system and, due to the geometrical parameters chosen, the coupling efficiency is as high as 50–90%. Linear dimensions and terminations applied allow for pulses up to a width of 12ns and up to a voltage level of 4–5 kV on the outside conductor. These pulse parameters proved to be sufficient to upset the DUTs tested so far.</p><p style=&quot;line-height: 20px;&quot;> In more than 400 measurements a rectangular pulse of increasing voltage level was applied to different types of CMOS and TTL until the individual DUT was damaged. As well the pulse width (3, 6 or 12 ns) and its polarity were varied in single-shot or repetitive-shot experiments (500 shots per voltage at a repetition rate of 3 Hz). The state of the DUT was continuously monitored by measuring both the current of the DUT circuit and that of the oscillator providing the operating signal for the DUT.</p><p style=&quot;line-height: 20px;&quot;> The results show a very good reproducibility within a set of identical samples, remarkable differences between manufacturers and lower thresholds for repetitive testing, which indicates a memory effect of the DUT to exist for voltage levels significantly below the single-shot threshold

Energy spread of ultracold electron bunches extracted from a laser cooled gas

Ultrashort and ultracold electron bunches created by near-threshold femtosecond photoionization of a laser-cooled gas hold great promise for single-shot ultrafast diffraction experiments. In previous publications the transverse beam quality and the bunch length have been determined. Here the longitudinal energy spread of the generated bunches is measured for the first time, using a specially developed Wien filter. The Wien filter has been calibrated by determining the average deflection of the electron bunch as a function of magnetic field. The measured relative energy spread $\frac{\sigma_{U}}{U} = 0.64 \pm 0.09\%$ agrees well with the theoretical model which states that it is governed by the width of the ionization laser and the acceleration length

A high-throughput screen identifying sequence and promiscuity characteristics of the loxP spacer region in Cre-mediated recombination

BACKGROUND: Cre-loxP recombination refers to the process of site-specific recombination mediated by two loxP sequences and the Cre recombinase protein. Transgenic experiments exploit integrative recombination, where a donor plasmid carrying a loxP site and DNA of interest integrate into a recipient loxP site in a target genome. Unfortunately, integrative recombination is highly inefficient because the insert is flanked by two loxP sites, which themselves become targets for Cre and lead to subsequent excision of the insert. A small number of mutations have been discovered in parts of the loxP sequence, specifically the spacer and inverted repeat segments, that increase the efficiency of integrative recombination. In this study we introduce a high-throughput in vitro assay to rapidly detect novel loxP spacer mutants and describe the sequence characteristics of successful recombinants. RESULTS: We created synthetic loxP oligonucleotides that contained a combination of inverted repeat mutations (the lox66 and lox71 mutations) and mutant spacer sequences, degenerate at 6 of the 8 positions. After in vitro Cre recombination, 3,124 recombinant clones were identified by sequencing. Included in this set were 31 unique, novel, self-recombining sequences. Using network visualization tools, we recognized 12 spacer sets with restricted promiscuity. We observed that increased guanine content at all spacer positions save for position 8 resulted in increased recombination. Interestingly, recombination between identical spacers was not preferred over non-identical spacers. We also identified a set of 16 pairs of loxP spacers that reacted at least twice with another spacer, but not themselves. Further, neither the wild-type P1 phage loxP sequence nor any of the known loxP spacer mutants appeared to be kinetically favoured by Cre recombinase. CONCLUSION: This study approached loxP spacer mutant screening in an unbiased manner, assuming nothing about candidate loxP sites save for the conserved 4 and 5 spacer positions. Candidate sites were free to recombine with any other sequence in the pool of all possible sites. The subset of loxP sites identified here are candidates for in vivo serial recombination as they have already demonstrated limited promiscuity with other loxP spacer and stability in the presence of Cre

Mapping by Cooperative Mobile Robots.

Constructing a system of intelligent robotic mapping agents that can function in an unstructured and unknown environment is a challenging task. With the exploration of our solar system as well as our own planet requiring more robust mapping agents, and with the drastic drop in the price of technology versus the gains in performance, robotic mapping is becoming a focus of research like never before. Efforts are underway to send mobile robots to map bodies within our solar system. While much of the research in robotic map construction has been focused on building maps used by the robotic agents themselves, very little has been done in building maps usable by humans. And yet it is the human that drives the need for mapping solutions. We propose a computational framework for building mobile robotic mapping systems to be deployed in unknown environments. This is the first work known to address the general problem of mapping in unknown terrain under the affect of error in readings, operations and systems that employs more than a single robot. The system draws upon the strengths from research in various robotic related areas by selecting those components and ideas that show promise when applied to mapping for human reading via a distributed network of heterogeneous mobile robots. This application of multiple mobile robots and the application to human end-users is a new direction in robotics research. We also propose and develop a new paradigm for storing mapping-agent generated data in a way that allows rapid map construction and correction to compensate for detected errors. We experimentally test the paradigm on a simulated robotic environment and analyze the results and show that there is a definite gain from correction, particularly in error rich environments. We also develop methods by which to apply corrections to the map and test their effectiveness. Finally we propose some extensions to this work and suggest research in areas not completely covered by our discussion

Constructing large DNA segments by iterative clone recombination

Methods for constructing large contiguous segments of DNA will be enabling for Synthetic Biology, where the assembly of genes encoding circuits, biosynthetic pathways or even whole microbial organisms is of interest. Currently, in vitro approaches to DNA synthesis are adequate for generating DNAs that are up to 10s of kbp in length, and in vivo recombination strategies are more suitable for building DNA constructs that are 100 kbp or larger. We have developed a vector system for efficient assembly of large DNA molecules by iterative in vivo recombination of fosmid clones. Two custom fosmid vectors have been built, pFOSAMP and pFOSKAN, that support antibiotic switching. Using this technique we rebuilt two non-contiguous regions of the Haemophilus influenzae genome as episomes in recombinogenic Escherichia coli host cells. These regions together comprise190 kbp, or 10.4% of the H. influenze genome

High-throughput sequencing: a failure mode analysis

BACKGROUND: Basic manufacturing principles are becoming increasingly important in high-throughput sequencing facilities where there is a constant drive to increase quality, increase efficiency, and decrease operating costs. While high-throughput centres report failure rates typically on the order of 10%, the causes of sporadic sequencing failures are seldom analyzed in detail and have not, in the past, been formally reported. RESULTS: Here we report the results of a failure mode analysis of our production sequencing facility based on detailed evaluation of 9,216 ESTs generated from two cDNA libraries. Two categories of failures are described; process-related failures (failures due to equipment or sample handling) and template-related failures (failures that are revealed by close inspection of electropherograms and are likely due to properties of the template DNA sequence itself). CONCLUSIONS: Preventative action based on a detailed understanding of failure modes is likely to improve the performance of other production sequencing pipelines

Störunempfindlichkeit von Ethernet in der Luftfahrt

In der Luftfahrzeugtechnik wurden früher viele einzelne Signalleitungen als Punkt-zuPunkt Verbindung verwendet. In der Regel hatten diese Signale eine gemeinsame Referenzmasse. Um die EMV zu verbessern, wurde eine Routentrennung eingeführt: Einzelne Leitungen werden nach Empfindlichkeit und Störpotential zusammengefasst und getrennt verlegt. Routentrennung ist auch außerhalb der Luftfahrt z. B. im Schiffbau eine bewährte EMV Maßnahme zusätzlich zur Gerätequalifikation. Das heißt die separate Führung einzelner Signalleitungen führt nicht systematisch zu einer Lockerung der Spezifikation angeschlossener Geräte. In modernen Luftfahrzeugen befindet sich eine steigende Anzahl elektronischer Systeme. Diese sind in zunehmend untereinander vernetzt. Mit erhöhter Anzahl und Komplexität der Flugzeugsysteme sind einzelne Signalleitungen nicht mehr Stand der Technik denn der Installationsraum ist begrenzt, und Gewichtsanforderungen sprechen dagegen. Aus diesem Grund werden Datenbusse und Netzwerke verlegt. Aus EMV Sicht hat der Übergang zu modernen Bussystemen den großen Vorteil einer erheblich gesteigerten Störfestigkeit der Signalübertragung. Die gesamte Anzahl der Leitungen in einem modernen Luftfahrzeug ist dennoch sehr hoch. Dementsprechend erfordert eine Routentrennung eine sehr aufwändige Leitungsarchitektur. Angesichts einer möglichst störfesten Auslegung moderner Bussysteme stellt sich die Frage, inwieweit Routentrennung als zur Absicherung der Störfestigkeit von Datenübertragungsleitungen überhaupt noch notwendig ist. Um zu belegen, dass für ein bestimmtes Übertragungsverfahren keine besondere Routenführung zur Sicherstellung der EMV erforderlich ist, muss gezeigt werden, dass die übertragenen Signale unter dem Einfluss der Flugzeugumgebung und benachbarter Störsignale hinreichend stabil sind und nicht signifikant beeinträchtigt werden. Die Grundlage dafür ist die tatsächliche elektromagnetische Flugzeugumgebung (EM environment). Diese Umgebung ist in der Form standardisierter EMV-Prüfungen und maximaler Störgrößen bekannt. Per Definition arbeitet qualifiziertes Gerät in dieser Umgebung störungsfrei. Wenn Daten in dieser Umgebung ebenfalls störungsfrei übertragen werden, ist eine Routentrennung für dieses Übertragungsverfahren überflüssig. Eine allgemeine Regel zur Routenführung eines gegebenen Standards erfordert die Betrachtung der eingekoppelten Störgrößen im Verhältnis zur Signalgröße. In diesem Paper wird exemplarisch Fast Ethernet nach dem IEEE 802.3 Standard auf Störfestigkeit gegen Leitungskopplung geprüft und zwar niederfrequentes Nebensprechen und HIRF (high intensity radiated fields). Es zeigt sich, dass die Gerätequalifikation ausreicht, um die Störfestigkeit der Ethernet Verbindung unabhängig von der Route nachzuweisen. In gleicher Weise können alle Bussysteme analysiert werden, um die Kabelverlegung massiv zu vereinfachen. Die vorliegende Arbeit beschränkt sich auf die EMV. Es ist zu beachten, dass es außerhalb der EMV andere Zwänge für die Routentrennung geben kann, z.B. Redundanz

Long-Read Sequencing of an Advanced Cancer Cohort Resolves Rearrangements, Unravels Haplotypes, and Reveals Methylation Landscapes

The Long-Read Personalized OncoGenomics (POG) dataset comprises a cohort of 189 patient tumors and 41 matched normal samples sequenced using the Oxford Nanopore Technologies PromethION platform. This dataset from the POG program and the Marathon of Hope Cancer Centres Network includes DNA and RNA short-read sequence data, analytics, and clinical information. We show the potential of long-read sequencing for resolving complex cancer-related structural variants, viral integrations, and extrachromosomal circular DNA. Long-range phasing facilitates the discovery of allelically differentially methylated regions (aDMRs) and allele-specific expression, including recurrent aDMRs in the cancer genes RET and CDKN2A. Germline promoter methylation in MLH1 can be directly observed in Lynch syndrome. Promoter methylation in BRCA1 and RAD51C is a likely driver behind homologous recombination deficiency where no coding driver mutation was found. This dataset demonstrates applications for long-read sequencing in precision medicine and is available as a resource for developing analytical approaches using this technology

Cloning whole bacterial genomes in yeast

Most microbes have not been cultured, and many of those that are cultivatable are difficult, dangerous or expensive to propagate or are genetically intractable. Routine cloning of large genome fractions or whole genomes from these organisms would significantly enhance their discovery and genetic and functional characterization. Here we report the cloning of whole bacterial genomes in the yeast Saccharomyces cerevisiae as single-DNA molecules. We cloned the genomes of Mycoplasma genitalium (0.6 Mb), M. pneumoniae (0.8 Mb) and M. mycoides subspecies capri (1.1 Mb) as yeast circular centromeric plasmids. These genomes appear to be stably maintained in a host that has efficient, well-established methods for DNA manipulation