103,158 research outputs found
Webscience, 'social machines' and principles for redesigning theories of agency: a prolegomenon
No full textThis paper argues that the advent of the WWW and the principles now developing for the move ‘social machines’ has posed serious challenges to traditional social theory. In particular, it is argued that the concept of social machines and the forms of distributed agency they imply amplify ‘deep flaws’ in the underlying principles of current agency theories that make empirical work using such frameworks ‘undecidable’. The occasioning of social machines and the WWW here are examined for the ways in which the traditional models of agency, involving reflexivity/skill dynamics, can be dismantled and new principles for re-designed agency theory posed. One key problem and three re-design principles are identified
The Ability of Cyanobacterial Cells to Restore UV-B Radiation Induced Damage to Photosystem II is Influenced by Photolyase Dependent DNA Repair
Get PDFDamage of DNA and Photosystem-II are among the most significant effects of UV-B irradiation in photosynthetic organisms. Both damaged DNA and Photosystem-II can be repaired, which represent important defense mechanisms against detrimental UV-B effects. Correlation of Photosystem-II damage and repair with the concurrent DNA damage and repair was investigated in the cyanobacterium Synechocystis PCC6803 using its wild type and a photolyase deficient mutant, which is unable to repair UV-B induced DNA damages. A significant amount of damaged DNA accumulated during UV-B exposure in the photolyase mutant concomitant with decreased Photosystem-II activity and D1 protein amount. The transcript level of psbA3, which is a UV-responsive copy of the psbA gene family encoding the D1 subunit of the Photosystem-II reaction center, is also decreased in the photolyase mutant. The wild-type cells, however, did not accumulate damaged DNA during UV-B exposure, suffered smaller losses of Photosystem-II activity and D1 protein, and maintained higher level of psbA3 transcripts than the photolyase mutant. It is concluded that the repair capacity of Photosystem-II depends on the ability of cells to repair UV-B-damaged DNA through maintaining the transcription of genes, which are essential for protein synthesis-dependent repair of the Photosystem-II reaction center
Correction to: The possibilities and practicalities of professional learning in support of Indigenous student experiences in schooling: A systematic review
No full textCorrection to: The Australian Educational Researcher https://doi.org/10.1007/s13384-019-00313-7
In the original publication of the article, the author group was incorrectly published without the co-authors. The correct author group is “Greg Vass, Kevin Lowe, Cathie Burgess, Neil Harrison, Nikki Moodie”.No Full Tex
Regular Separators for {VASS} Coverability Languages
Get PDFWe study regular separators of vector addition systems (VASS, for short) with coverability semantics. A regular language R is a regular separator of languages K and L if K ⊆ R and L ∩ R = ∅. It was shown by Czerwiński, Lasota, Meyer, Muskalla, Kumar, and Saivasan (CONCUR 2018) that it is decidable whether, for two given VASS, there exists a regular separator. In fact, they show that a regular separator exists if and only if the two VASS languages are disjoint. However, they provide a triply exponential upper bound and a doubly exponential lower bound for the size of such separators and leave open which bound is tight.
We show that if two VASS have disjoint languages, then there exists a regular separator with at most doubly exponential size. Moreover, we provide tight size bounds for separators in the case of fixed dimensions and unary/binary encodings of updates and NFA/DFA separators. In particular, we settle the aforementioned question.
The key ingredient in the upper bound is a structural analysis of separating automata based on the concept of basic separators, which was recently introduced by Czerwiński and the second author. This allows us to determinize (and thus complement) without the powerset construction and avoid one exponential blowup
Non-Elementary Complexities for Branching VASS, MELL, and Extensions
Get PDFWe study the complexity of reachability problems on branching extensions of
vector addition systems, which allows us to derive new non-elementary
complexity bounds for fragments and variants of propositional linear logic. We
show that provability in the multiplicative exponential fragment is Tower-hard
already in the affine case -- and hence non-elementary. We match this lower
bound for the full propositional affine linear logic, proving its
Tower-completeness. We also show that provability in propositional contractive
linear logic is Ackermann-complete.Comment: Fixed Fig. 3 thanks to Hiromi Tanak
Correction to: ‘Aboriginal Voices’: An overview of the methodology applied in the systematic review of recent research across ten key areas of Australian Indigenous education (The Australian Educational Researcher, (2019), 46, 2, (213-229), 10.1007/s13384-019-00307-5)
Get PDFIn the original publication of the article, the author name “Cathie Burgess” was inadvertently missed in the author group. The correct author group is “Kevin Lowe · Christine Tennent · John Guenther · Neil Harrison · Cathie Burgess · Nikki Moodie · Greg Vass”. Cathie Burgess coordinates Aboriginal Studies, Aboriginal Community Engagement and the Master of Education: Leadership in Aboriginal Education programs at the University of Sydney. Cathie’s research involves community-led initiatives positioning Aboriginal cultural educators as experts through projects such as Learning from Country in the City, Aboriginal Voices: Insights into Aboriginal Education and Redfern Cultural Program. The original article has been corrected
An algorithm constructing the semilinear for 2-dim Reset/Transfer VASS (Extended Abstract)
No full textThe main result of this paper is a proof that the reachability set (post*) of any 2-dim Reset/Transfer Vector Addition System with States is an effectively computable semilinear set. Our result implies that numerous boundedness and reachability properties are decidable for this class. Since the traditional Karp and Miller's algorithm does not terminate when applied to 2-dim Reset/Transfer VASS, we introduce, as a tool for the proof, a new technique to construct a finite coverability tree for this class
Social justice and race critical education research (Editorial)
No full text‘Consider, for example, educators’ and educational researchers’ concerns with assimilation, civilization, vocational training, IQ, poverty, cultural difference, remedial education, school readiness, achievement gaps, accountability, and standardization – all of these conversations were and still are intimately connected to race and racism regardless of whether we name them as such’ (Brayboy, Castagno, & Maughan, 2007, p. 159). The roll-out of national testing in Australia, and the subsequent yearly discussions of educational achievements, has contributed to reigniting concerns regarding the presence and effects of race in education. In part, this is because comparisons based on the results of these tests, for example, between Indigenous Australian and non-Indigenous Australian students (Ford, 2013), or LBOTE (language background other than English) and non-LBOTE students (Creagh, 2014), invite critique regarding the pervasive and pernicious ongoing impact of racism on the engagement and experiences of learners in schools (Lingard, Creagh, & Vass, 2012; Sarra, 2011; Walton, Priest, & Paradies, 2013). The growing impact and pressure associated with standardised and often ‘high-stakes’ testing, coupled with heightened concern about race and racism in education, is also a significant issue in settings such as the USA and UK, as indicated in the quote that opens this editorial.No Full Tex
Regular Separability in Büchi VASS
Get PDFWe study the (ω-)regular separability problem for Büchi VASS languages: Given two Büchi VASS with languages L₁ and L₂, check whether there is a regular language that fully contains L₁ while remaining disjoint from L₂. We show that the problem is decidable in general and PSPACE-complete in the 1-dimensional case, assuming succinct counter updates. The results rely on several arguments. We characterize the set of all regular languages disjoint from L₂. Based on this, we derive a (sound and complete) notion of inseparability witnesses, non-regular subsets of L₁. Finally, we show how to symbolically represent inseparability witnesses and how to check their existence
Polyphase deformation and fluid flow in the Internal Ligurian Units, Italy
Get PDFWe studied the Internal Ligurian Unit (ILU) of the Northern Apennines, Italy. Field observations, fold axes, stylo-
lites and crenulation cleavages indicate that the first folding had a direction of NW-SE, whereas the second main
folding was in the direction of NE-SW. These orientations are in accordance with previous studies attributing the
first folding to a E-SE-dipping, early subduction, and the second (main) folding to the accretion of the sequence
towards the NE in a W-SW-dipping subduction zone. The unfolding of conjugate veins along the second folding
axes showed the rotation of the main horizontal stresses. Oldest conjugates formed during the deformation in the
SE-dipping subduction zone. As the subduction polarity-flip occurred and the subduction zone migrated towards
its current strike direction, NW-SE, the main horizontal stresses also rotated forming conjugates triggered by E-W,
NE-SW and N-S compression. Tectonic stylolites found in the Val Lavagna Shale also reflect these compression
directions. In addition to conjugates, several other vein types (e.g. bed-parallel and perpendicular, folding-related
veins, blobs of mineralization) were observed in the Palombini and Val Lavagna Shale. As the veins intensity was
increasing towards the Palombini-Val Lavagna boundary that is considered a fault-contact, we propose that fluid
flow along the fault was responsible for the veining. Microstructural evidence, however, also suggested that diffu-
sion from the host rock and dissolution of the veins could have contributed locally to material transport. Early veins
show combinations of layer parallel and perpendicular veins and probably represent fluid overpressures. However
these features are relatively local
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