The Complexity of Reasoning for Fragments of Default Logic

Default logic was introduced by Reiter in 1980. In 1992, Gottlob classified the complexity of the extension existence problem for propositional default logic as \SigmaPtwo-complete, and the complexity of the credulous and skeptical reasoning problem as SigmaP2-complete, resp. PiP2-complete. Additionally, he investigated restrictions on the default rules, i.e., semi-normal default rules. Selman made in 1992 a similar approach with disjunction-free and unary default rules. In this paper we systematically restrict the set of allowed propositional connectives. We give a complete complexity classification for all sets of Boolean functions in the meaning of Post's lattice for all three common decision problems for propositional default logic. We show that the complexity is a hexachotomy (SigmaP2-, DeltaP2-, NP-, P-, NL-complete, trivial) for the extension existence problem, while for the credulous and skeptical reasoning problem we obtain similar classifications without trivial cases.Comment: Corrected versio

A Modern Copyright Framework for the Internet of Things (IoT): Intellectual Property Scholars\u27 Joint Submission to the Canadian Government Consultation

In response to the Canadian government consultation process on the modernization of the copyright framework launched in the summer 2021, we hereby present our analysis and recommendations concerning the interaction between copyright and the Internet of Things (IoT). The recommendations herein reflect the shared opinion of the intellectual property scholars who are signatories to this brief. They are informed by many combined decades of study, teaching, and practice in Canadian, US, and international intellectual property law.In what follows, we explain:•The importance of approaching the questions raised in the consultation with a firm commitment to maintaining the appropriate balance of rights and interests in Canada’s copyright system, within the broader framework of the Constitution;•That the modernization of the Copyright Act requires a careful examination of the copyright framework within larger observable trends of dominant positions in the marketplace and anti-competitive practices, of the extraction of big (personal) data, and of market and legal infrastructures’ heavy reliance on non-negotiated standard form contracts;-That the growing prevalence of the IoT shows more clearly than ever before why Technological Protection Measures (TPMs) need to be recalibrated in keeping with the objectives of copyright, the Constitution, property rights, and of promoting competitive markets.As such, we recommend:-To narrow the scope of the TPM prohibitions under the Copyright Act, whereby the circumvention of access controls or copy controls for non-copyright-infringing purposes would be lawful, with a non-exhaustive list of such purposes to provide greater legal certainty. The same treatment would apply to the dealing in TPM circumvention technology enabling the exercise of non-copyright-infringing purposes.In the alternative, the Copyright Act should be amended to:-Introduce a new exception that would confirm that the TPM provisions (and other relevant exclusive rights in the Copyright Act) do not apply to the right to repair, including for maintenance and diagnostics purposes.-Introduce a new exception to encourage follow-on innovation.-Additionally, just as copyright holders should not be allowed to contract out of exceptions to copyright infringement through non-negotiated standard form agreements, neither should they be allowed to opt out of exceptions to TPM prohibitions by contract

A Modern Copyright Framework for Artificial Intelligence: IP Scholars\u27 Joint Submission to the Canadian Government Consultation

In response to the Canadian government consultation process on the modernization of the copyright framework launched in the summer 2021, we hereby present our analysis and recommendations concerning the interaction between copyright and artificial intelligence (AI). The recommendations herein reflect the shared opinion of the intellectual property scholars who are signatories to this brief. They are informed by many combined decades of study, teaching, and practice in Canadian and international intellectual property law.In what follows, we explain:- The importance of approaching the questions raised in the consultation with a firm commitment to maintaining the appropriate balance of rights and interests in Canada’s copyright system, consistent with a robust principle of technological neutrality.- The importance of ensuring that text and data mining (TDM) activity can be undertaken in Canada without the threat of potential copyright liability. We therefore propose both an opening up of Canada’s fair dealing doctrine to better accommodate TDM activities, and the enactment of a specific statutory provision to confirm that uses of copyright works and other subject matter for TDM (whether commercial or non-commercial) do not infringe copyright.- The importance of resisting calls to extend copyright protection to AI-generated outputs. We therefore propose maintaining and confirming the existing principled requirements of human authorship and original expression as preconditions of copyright protection, and we caution against any move to establish new neighbouring or sui generis rights in respect of AI outputs. Works generated by AI should remain in the public domain.As such, we recommend:- Enacting a broad statutory provision confirming that use of a work or other subject matter for TDM does not infringe copyright. This specific exception should be available to all users, apply to commercial and noncommercial uses, permit the retention and sharing of copies, and be protected from contractual override.- Amending section 29 of the Copyright Act to make the list of purposes an illustrative list (“for purposes such as”) and adding TDM or data/informational analysis as an enumerated purpose therein.- Confirming in section 2 of the Copyright Act that “author” means a human being/natural person; and confirming in section 5 of the Copyright Act that copyright shall not subsist in a work created without a human author

The Role of Actin in Spindle Orientation Changes during the Saccharomyces cerevisiae Cell Cycle

In the budding yeast Saccharomyces cerevisiae, the mitotic spindle must align along the mother-bud axis to accurately partition the sister chromatids into daughter cells. Previous studies showed that spindle orientation required both astral microtubules and the actin cytoskeleton. We now report that maintenance of correct spindle orientation does not depend on F-actin during G2/M phase of the cell cycle. Depolymerization of F-actin using Latrunculin-A did not perturb spindle orientation after this stage. Even an early step in spindle orientation, the migration of the spindle pole body (SPB), became actin-independent if it was delayed until late in the cell cycle

Phosphorylation of bamboo mosaic virus satellite RNA (satBaMV)-encoded protein P20 downregulates the formation of satBaMV-P20 ribonucleoprotein complex

Bamboo mosaic virus (BaMV) satellite RNA (satBaMV) depends on BaMV for its replication and encapsidation. SatBaMV-encoded P20 protein is an RNA-binding protein that facilitates satBaMV systemic movement in co-infected plants. Here, we examined phosphorylation of P20 and its regulatory functions. Recombinant P20 (rP20) was phosphorylated by host cellular kinase(s) in vitro, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and mutational analyses revealed Ser-11 as the phosphorylation site. The phosphor-mimic rP20 protein interactions with satBaMV-translated mutant P20 were affected. In overlay assay, the Asp mutation at S11 (S11D) completely abolished the self-interaction of rP20 and significantly inhibited the interaction with both the WT and S11A rP20. In chemical cross-linking assays, S11D failed to oligomerize. Electrophoretic mobility shift assay and subsequent Hill transformation analysis revealed a low affinity of the phospho-mimicking rP20 for satBaMV RNA. Substantial modulation of satBaMV RNA conformation upon interaction with nonphospho-mimic rP20 in circular dichroism analysis indicated formation of stable satBaMV ribonucleoprotein complexes. The dissimilar satBaMV translation regulation of the nonphospho- and phospho-mimic rP20 suggests that phosphorylation of P20 in the ribonucleoprotein complex converts the translation-incompetent satBaMV RNA to messenger RNA. The phospho-deficient or phospho-mimicking P20 mutant of satBaMV delayed the systemic spread of satBaMV in co-infected Nicotiana benthamiana with BaMV. Thus, satBaMV likely regulates the formation of satBaMV RNP complex during co-infection in planta

Advances in gene therapy for muscular dystrophies

Duchenne muscular dystrophy (DMD) is a recessive lethal inherited muscular dystrophy caused by mutations in the gene encoding dystrophin, a protein required for muscle fibre integrity. So far, many approaches have been tested from the traditional gene addition to newer advanced approaches based on manipulation of the cellular machinery either at the gene transcription, mRNA processing or translation levels. Unfortunately, despite all these efforts, no efficient treatments for DMD are currently available. In this review, we highlight the most advanced therapeutic strategies under investigation as potential DMD treatments

Representing Fitness Landscapes by Valued Constraints to Understand the Complexity of Local Search

Local search is widely used to solve combinatorial optimisation problems and to model biological evolution, but the performance of local search algorithms on different kinds of fitness landscapes is poorly understood. Here we introduce a natural approach to modelling fitness landscapes using valued constraints. This allows us to investigate minimal representations (normal forms) and to consider the effects of the structure of the constraint graph on the tractability of local search. First, we show that for fitness landscapes representable by binary Boolean valued constraints there is a minimal necessary constraint graph that can be easily computed. Second, we consider landscapes as equivalent if they allow the same (improving) local search moves; we show that a minimal normal form still exists, but is NP-hard to compute. Next we consider the complexity of local search on fitness landscapes modelled by valued constraints with restricted forms of constraint graph. In the binary Boolean case, we prove that a tree-structured constraint graph gives a tight quadratic bound on the number of improving moves made by any local search; hence, any landscape that can be represented by such a model will be tractable for local search. We build two families of examples to show that both the conditions in our tractability result are essential. With domain size three, even just a path of binary constraints can model a landscape with an exponentially long sequence of improving moves. With a treewidth two constraint graph, even with a maximum degree of three, binary Boolean constraints can model a landscape with an exponentially long sequence of improving moves

Induction of vacuolar invertase inhibitor mRNA in potato tubers contributes to cold-induced sweetening resistance and includes spliced hybrid mRNA variants

Cold storage of tubers of potato (Solanum tuberosum L.) compromises tuber quality in many cultivars by the accumulation of hexose sugars in a process called cold-induced sweetening. This is caused by the breakdown of starch to sucrose, which is cleaved to glucose and fructose by vacuolar acid invertase. During processing of affected tubers, the high temperatures involved in baking and frying cause the Maillard reaction between reducing sugars and free amino acids, resulting in the accumulation of acrylamide. cDNA clones with deduced proteins homologous to known invertase inhibitors were isolated and the two most abundant forms, termed INH1 and INH2, were shown to possess apoplastic and vacuolar localization, respectively. The INH2 gene showed developmentally regulated alternative splicing, so, in addition to the INH2α transcript encoding the full-length protein, two hybrid mRNAs (INH2β*A and INH2β*B) that encoded deduced vacuolar invertase inhibitors with divergent C-termini were detected, the result of mRNA splicing of an upstream region of INH2 to a downstream region of INH1. Hybrid RNAs are common in animals, where they may add to the diversity of the proteome, but are rarely described in plants. During cold storage, INH2α and the hybrid INH2β mRNAs accumulated to higher abundance in cultivars resistant to cold-induced sweetening than in susceptible cultivars. Increased amounts of invertase inhibitor may contribute to the suppression of acid invertase activity and prevent cleavage of sucrose. Evidence for increased RNA splicing activity was detected in several resistant lines, a mechanism that in some circumstances may generate a range of proteins with additional functional capacity to aid adaptability