Search results for "circular"

On the regularity of circular splicing languages : A survey and new developments

2009

Circular splicing has been introduced to model a specific recombinant behaviour of circular DNA, continuing the investigation initiated with linear splicing. In this paper we focus on the relationship between regular circular languages and languages generated by finite circular splicing systems. We survey the known results towards a characterization of the intersection between these two classes and provide new contributions on the open problem of finding this characterization. First, we exhibit a non-regular circular language generated by a circular simple system thus disproving a known result in this area. Then we give new results related to a restrictive class of circular splicing systems…

Marked systems and circular splicing

2007

Splicing systems are generative devices of formal languages, introduced by Head in 1987 to model biological phenomena on linear and circular DNA molecules. In this paper we introduce a special class of finite circular splicing systems named marked systems. We prove that a marked system S generates a regular circular language if and only if S satisfies a special (decidable) property. As a consequence, we show that we can decide whether a regular circular language is generated by a marked system and we characterize the structure of these regular circular languages.

Circular sturmian words and Hopcroft’s algorithm

2009

AbstractIn order to analyze some extremal cases of Hopcroft’s algorithm, we investigate the relationships between the combinatorial properties of a circular sturmian word (x) and the run of the algorithm on the cyclic automaton Ax associated to (x). The combinatorial properties of words taken into account make use of sturmian morphisms and give rise to the notion of reduction tree of a circular sturmian word. We prove that the shape of this tree uniquely characterizes the word itself. The properties of the run of Hopcroft’s algorithm are expressed in terms of the derivation tree of the automaton, which is a tree that represents the refinement process that, in the execution of Hopcroft’s alg…

Electrically Driven Magnetic Domain Wall Rotation in Multiferroic Heterostructures to Manipulate Suspended On-Chip Magnetic Particles

2015

In this work, we experimentally demonstrate deterministic electrically driven, strain-mediated domain wall (DW) rotation in ferromagnetic Ni rings fabricated on piezoelectric [Pb(Mg1/3Nb2/3)O3]0.66-[PbTiO3]0.34 (PMN-PT) substrates. While simultaneously imaging the Ni rings with X-ray magnetic circular dichroism photoemission electron microscopy, an electric field is applied across the PMN-PT substrate that induces strain in the ring structures, driving DW rotation around the ring toward the dominant PMN-PT strain axis by the inverse magnetostriction effect. The DW rotation we observe is analytically predicted using a fully coupled micromagnetic/elastodynamic multiphysics simulation, which v…

The new 5- or 6-azapyrimidine and cyanuric acid derivatives of L-ascorbic acid bearing the free C-5 hydroxy or C-4 amino group at the ethylenic space…

2011

Abstract We report on the synthesis of the novel types of cytosine and 5-azacytosine (1–9), uracil and 6-azauracil (13–18) and cyanuric acid (19–22) derivatives of l -ascorbic acid, and on their cytostatic activity evaluation in human malignant tumour cell lines vs. their cytotoxic effects on human normal fibroblasts (WI38). The CD spectra analysis revealed that cytosine (5 and 6), uracil (14–16), 6-azauracil (17) and cyanuric acid (21) derivatives of l -ascorbic acid bearing free amino group at ethylenic spacer existed as a racemic mixture of enantiomers, whereas L-ascorbic derivatives containing the C-5 substituted hydroxy group at the ethylenic spacer were obtained in (4R, 5S) enantiomer…

On the interaction of doxorubicin with polynucleotides

2014

The interaction of doxorubicin (DX) with model polynucleotides poly(dG-dC)·poly(dG-dC) (polyGC), poly(dA-dT)·poly(dA-dT) (poly-AT), and calf thymus DNA has been studied by several spectroscopic techniques in phosphate buffer aqueous solutions. UV−vis, circular dichroism, and fluorescence spectroscopic data confirm that intercalation is the prevailing mode of interaction, and also reveal that the interaction with AT-rich regions leads to the transfer of excitation energy to DX not previously documented in the literature. Moreover, the DX affinity for AT sites has been found to be on the same order of magnitude as that reported for GC sites.

Scale-up of electrodialysis with bipolar membrane (EDBM) unit for valorisation of waste brine by experimental analysis

2022

Reflections on the Hohmann Transfer

2004

Walter Hohmann was a civil engineer who studied orbital maneuvers in his spare time. In 1925, he published an important book (Ref. 1) containing his main result, namely, that the most economical transfer from a circular orbit to another circular orbit is achieved via an elliptical trajectory bitangent to the terminal orbits. With the advent of the space program some three decades later, the Hohmann transfer maneuver became the most fundamental maneuver in space. In this work, we present a complete study of the Hohmann transfer maneuver. After revisiting its known properties, we present a number of supplementary properties which are essential to the qualitative understanding of the maneuver.…

Life cycle assessment of a new industrial process for sustainable construction materials

2023

One of the key sectors for the green transition of European countries is construction, that is more and more asked to evolve towards innovative ecological binders and green cost-effective processes. The construction sector is highly energy intensive, and the cement production is one of the main sources of environmental pollution in the world. In this regard, GeoPolymers (GP) seem to be promising for a sustainable replacement of cementitious materials. Therefore, the Life Cycle Assessment (LCA) of the industrial production of different formulations of Geopolymer Concrete (GC) was performed in this study after scaling up the Life Cycle Inventory (LCI) from a laboratory scale to an industrial …

The creative class: do jobs follow people or do people follow jobs?

2017

Accepted manuscript version. Published version available in Regional Studies, DOI: 10.1080/00343404.2016.1254765 Regional adjustment models are applied to explore causal interaction between two types of people distinguished by educational attainment, and two types of jobs: creative class jobs and other jobs. Data used are for labour market regions in Finland, Norway and Sweden from the 2000s. Creative class jobs follow people with high educational attainment (one way causation), but creative class jobs also follow other jobs and vice versa (circular causation). The results suggest that stimulating creative class job growth could be accomplished through attracting people with higher educatio…