Extreme geomagnetic disturbances due to shocks within CMEs

We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth\u27s magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense geomagnetic storm is the 30 September 2012 event, which strongly depleted the outer radiation belt. We discuss the potential of shocks inside CMEs to cause large geomagnetic effects at Earth, including magnetopause shadowing

Paving the way for culturally competent robots: a position paper

Cultural competence is a well known requirement for an effective healthcare, widely investigated in the nursing literature. We claim that personal assistive robots should likewise be culturally competent, aware of general cultural characteristics and of the different forms they take indifferent individuals, and sensitive to cultural differences while perceiving, reasoning, and acting. Drawing inspiration from existing guidelines for culturally competent healthcare and the state-of-the-art in culturally competent robotics, we identify the key robot capabilities which enable culturally competent behaviours and discuss methodologies for their development and evaluation

Solar cycle effects in planetary geomagnetic activity: Analysis of 36‐year long OMNI dataset

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94796/1/grl13462.pd

Axiomatic systems and topological semantics for intuitionistic temporal logic

We propose four axiomatic systems for intuitionistic linear temporal logic and show that each of these systems is sound for a class of structures based either on Kripke frames or on dynamic topological systems. Our topological semantics features a new interpretation for the `henceforth' modality that is a natural intuitionistic variant of the classical one. Using the soundness results, we show that the four logics obtained from the axiomatic systems are distinct. Finally, we show that when the language is restricted to the `henceforth'-free fragment, the set of valid formulas for the relational and topological semantics coincide

Towards concolic testing for hybrid systems

Hybrid systems exhibit both continuous and discrete behavior. Analyzing hybrid systems is known to be hard. Inspired by the idea of concolic testing (of programs), we investigate whether we can combine random sampling and symbolic execution in order to effectively verify hybrid systems. We identify a sufficient condition under which such a combination is more effective than random sampling. Furthermore, we analyze different strategies of combining random sampling and symbolic execution and propose an algorithm which allows us to dynamically switch between them so as to reduce the overall cost. Our method has been implemented as a web-based checker named HYCHECKER. HYCHECKER has been evaluated with benchmark hybrid systems and a water treatment system in order to test its effectiveness.CPCI-S(ISTP)[email protected]; [email protected]

Long‐lived geomagnetic storms and coronal mass ejections

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94830/1/jgra18071.pd

Complete blockage of the mevalonate pathway results in male gametophyte lethality

Plants have two isoprenoid biosynthetic pathways: the cytosolic mevalonate (MVA) pathway and the plastidic 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. Since the discovery of the MEP pathway, possible metabolic cross-talk between these pathways has prompted intense research. Although many studies have shown the existence of such cross-talk using feeding experiments, it remains to be determined if native cross-talk, rather than exogenously applied metabolites, can compensate for complete blockage of the MVA pathway. Previously, Arabidopsis mutants for HMG1 and HMG2 encoding HMG-CoA reductase (HMGR) were isolated. Although it was shown that HMGR1 is a functional HMGR, the enzyme activity of HMGR2 has not been confirmed. It is demonstrated here that HMG2 encodes a functional reductase with similar activity to HMGR1, using enzyme assays and complementation experiments. To estimate the contribution of native cross-talk, an attempt was made to block the MVA pathway by making double mutants lacking both HMG1 and HMG2, but no double homozygotes were detected in the progeny of self-pollinated HMG1/hmg1 hmg2/hmg2 plants. hmg1 hmg2 male gametophytes appeared to be lethal based on crossing experiments, and microscopy indicated that ∼50% of the microspores from the HMG1/hmg1 hmg2/hmg2 plant appeared shrunken and exhibited poorly defined endoplasmic reticulum membranes. In situ hybridization showed that HMG1 transcripts were expressed in both the tapetum and microspores, while HMG2 mRNA appeared only in microspores. It is concluded that native cross-talk from the plastid cannot compensate for complete blockage of the MVA pathway, at least during male gametophyte development, because either HMG1 or HMG2 is required for male gametophyte development