Moving striations and anode effects in an argon glow discharge

Moving striations and anode oscillations were studied over a wide range of gas pressures and discharge currents in an argon glow discharge. Striation spacing, frequency and velocity were measured as a function of discharge current from low currents to the current for extinction of moving striations, for pressures from 1 to 16 mm Hg. Striation frequency was also measured as a function of pressure for various radii discharge tubes. The anode spot light oscillations were eliminated by use of an auxiliary anode discharge, which brought the positive column in contact with the anode and eliminated the oscillat­ing anode fall in potential. This change in the anode region produced no significant change in the striation parameters, but greatly reduced and altered the frequency of the poten­tial oscillations across the discharge tube. The potential oscillations now followed the wave form and frequency of the striation oscillations instead of the frequency of the anode spot oscillations. By use of a discharge tube, constructed with sections of different radius, moving striations in the positive column were isolated from both cathode and anode by sections of homogenous positive column in which no voltage oscillations were detectable by floating probes. This leads to the con­clusion that striations are due to an inherent instability of the positive column, and not to the effects developed by the anode or cathode.http://www.archive.org/details/movingstriations00habeCaptain, United States ArmyCaptain, United States ArmyApproved for public release; distribution is unlimited

Finite Automata for the Sub- and Superword Closure of CFLs: Descriptional and Computational Complexity

We answer two open questions by (Gruber, Holzer, Kutrib, 2009) on the state-complexity of representing sub- or superword closures of context-free grammars (CFGs): (1) We prove a (tight) upper bound of $2^{\mathcal{O}(n)}$ on the size of nondeterministic finite automata (NFAs) representing the subword closure of a CFG of size $n$. (2) We present a family of CFGs for which the minimal deterministic finite automata representing their subword closure matches the upper-bound of $2^{2^{\mathcal{O}(n)}}$ following from (1). Furthermore, we prove that the inequivalence problem for NFAs representing sub- or superword-closed languages is only NP-complete as opposed to PSPACE-complete for general NFAs. Finally, we extend our results into an approximation method to attack inequivalence problems for CFGs

Producing territory: territorial organizing of movements in Buenos Aires

In this paper we analyze the territorial organizing of two dissimilar social movements across Greater Buenos Aires, showing how urban struggles produce territory as a key element of their political practice. Through their relational, contested character, these Latin American territories foreground an alternative to state-centric, Anglo-American models of territorial politics. First, the unemployed workers' movements in the urban periphery show how the territorial organization of production and reproduction creates new social relations, and second, an assembly-organized market emphasizes the relationality of territory in constructing solidarity economies. This paper contributes to debates on urban social movements by showing that these movements use practices of territorial organizing to produce urban territory in distinct ways, and that territorial organizing is relational, contested, and central to movements' praxis

A digitally printed optoelectronic nose for the selective trace detection of nitroaromatic explosive vapours using fluorescence quenching

We report on a fluorescent optoelectronic nose for the trace detection of nitroaromatic explosive vapours. The sensor arrays, fabricated by aerosol-jet printing, consist of six different commercially available polymers as transducers. We assess the within-batch reproducibility of the printing process and we report that the sensor polymers show efficient fluorescence quenching capabilities with detection limits of a few parts-per-billion in air. We further demonstrate the nose\u27s ability to discriminate between several nitroaromatics including nitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene at three different concentrations using linear discriminant analysis. Our approach enables the realization of highly integrated optical sensor arrays in optoelectronic noses for the sensitive and selective detection of nitroaromatic explosive trace vapours using a potentially low-cost digital printing technique suitable for high-volume fabrication

Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap

We characterise the performance of a surface-electrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanical-system (MEMS) microfabrication processes which are in principle scalable to much larger ion trap arrays, as proposed for implementing ion trap quantum information processing. We measure rf ion micromotion parallel and perpendicular to the plane of the trap electrodes, and find that on-package capacitors reduce this to <~ 10 nm in amplitude. We also measure ion trapping lifetime, charging effects due to laser light incident on the trap electrodes, and the heating rate for a single trapped ion. The performance of this trap is found to be comparable with others of the same size scale.Comment: 6 pages, 10 figure

Foundations for decision problems in separation logic with general inductive predicates

Abstract. We establish foundational results on the computational com-plexity of deciding entailment in Separation Logic with general induc-tive predicates whose underlying base language allows for pure formulas, pointers and existentially quantified variables. We show that entailment is in general undecidable, and ExpTime-hard in a fragment recently shown to be decidable by Iosif et al. Moreover, entailment in the base language is ΠP2-complete, the upper bound even holds in the presence of list predicates. We additionally show that entailment in essentially any fragment of Separation Logic allowing for general inductive predicates is intractable even when strong syntactic restrictions are imposed.

Languages ordered by the subword order

We consider a language together with the subword relation, the cover relation, and regular predicates. For such structures, we consider the extension of first-order logic by threshold- and modulo-counting quantifiers. Depending on the language, the used predicates, and the fragment of the logic, we determine four new combinations that yield decidable theories. These results extend earlier ones where only the language of all words without the cover relation and fragments of first-order logic were considered

Investigating migration and mobility in the Early Roman frontier: The case of the Batavi in the Dutch Rhine delta (c. 50/30 BC–AD 40)

The study of migration is essential for understanding the earliest phases of the Roman period in the Lower Rhine delta. This paper applies an integrated and interdisciplinary approach, combining and comparing historical, archaeological and science-based evidence and methodologies, allowing a more detailed reconstruction of immigration during this period. Our study suggests that various groups migrated to our region, probably over a longer period of time, originating from different regions and arriving in a land with a (probably limited) residual population. This marked and varied immigration should be understood in the context of Roman frontier policy and the (ethnic) recruitment of Germanic groups by the Roman military.Material Culture Studie

Photoluminescence and Electron Spin Resonance of ilicon Dioxide Crystal with Rutile Structure (Stishovite)

This work was supported by ERANET MYND. Also, financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2017/2 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. The authors express our gratitude to R.I. Mashkovtsev for help in ESR signal interpretation. The authors are appreciative to T.I. Dyuzheva, L.M. Lityagina, N.A. Bendeliani for stishovite single crystals and to K. Hubner and H.-J. Fitting for stishovite powder of Barringer Meteor Crater.An electron spin resonance (ESR) and photoluminescence signal is observed in the as grown single crystal of stishovite indicating the presence of defects in the non‐irradiated sample. The photoluminescence of the as received stishovite single crystals exhibits two main bands – a blue at 3 eV and an UV at 4.75 eV. Luminescence is excited in the range of optical transparency of stishovite (below 8.75 eV) and, therefore, is ascribed to defects. A wide range of decay kinetics under a pulsed excitation is observed. For the blue band besides the exponential decay with a time constant of about 18 μs an additional ms component is revealed. For the UV band besides the fast component with a time constant of 1–3 ns a component with a decay in tens μs is obtained. The main components (18 μs and 1–3 ns) possess a typical intra‐center transition intensity thermal quenching. The effect of the additional slow component is related to the presence of OH groups and/or carbon molecular defects modifying the luminescence center. The additional slow components exhibit wave‐like thermal dependences. Photo‐thermally stimulated creation–destruction of the complex comprising host defect and interstitial modifiers explains the slow luminescence wave‐like thermal dependences.ERANET MYND; ISSP UL Nr. SJZ/2017/2 ; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

On the complexity of resource-bounded logics

We revisit decidability results for resource-bounded logics and use decision problems for vector addition systems with states (VASS) to characterise the complexity of (decidable) model-checking problems. We show that the model-checking problem for the logic RB+-ATL is 2EXPTIME-complete by using recent results on alternating VASS. In addition, we establish that the model-checking problem for RBTL is decidable and has the same complexity as for RBTL* (the extension of RBTL with arbitrary path formulae), namely EXPSPACE-complete, proving a new decidability result as a by-product of the approach. Finally, we establish that the model-checking problem for RB+-ATL* is decidable by a reduction to parity games, and show how to synthesise values for resource parameters