Explanation for case-based reasoning via abstract argumentation

Case-based reasoning (CBR) is extensively used in AI in support of several applications, to assess a new situation (or case) by recollecting past situations (or cases) and employing the ones most similar to the new situation to give the assessment. In this paper we study properties of a recently proposed method for CBR, based on instantiated Abstract Argumentation and referred to as AA-CBR, for problems where cases are represented by abstract factors and (positive or negative) outcomes, and an outcome for a new case, represented by abstract factors, needs to be established. In addition, we study properties of explanations in AA-CBR and define a new notion of lean explanations that utilize solely relevant cases. Both forms of explanations can be seen as dialogical processes between a proponent and an opponent, with the burden of proof falling on the proponent

Arrestin1 Mediates Light-Dependent Rhodopsin Endocytosis and Cell Survival

SummaryBackground: Arrestins are pivotal, multifunctional organizers of cell responses to GPCR stimulation, including cell survival and cell death. In Drosophila norpA and rdgC mutants, endocytosis of abnormally stable complexes of rhodopsin (Rh1) and fly photoreceptor Arrestin2 (Arr2) triggers cell death, implicating Rh1/Arr2-bearing endosomes in pro-cell death signaling, potentially via arrestin-mediated GPCR activation of effector kinase pathways. In order to further investigate arrestin function in photoreceptor physiology and survival, we studied Arr2’s partner photoreceptor arrestin, Arr1, in developing and adult Drosophila compound eyes.Results: We report that Arr1, but not Arr2, is essential for normal, light-induced rhodopsin endocytosis. Also distinct from Arr2, Arr1 is essential for light-independent photoreceptor survival. Photoreceptor cell death caused by loss of Arr1 is strongly suppressed by coordinate loss of Arr2. We further find that Rh1 C-terminal phosphorylation is essential for light-induced endocytosis and also for translocation of Arr1, but not Arr2, from dark-adapted photoreceptor cytoplasm to photosensory membrane rhabdomeres. In contrast to a previous report, we do not find a requirement for photoreceptor myosin kinase NINAC in Arr1 or Arr2 translocation.Conclusions: The two Drosophila photoreceptor arrestins mediate distinct and essential cell pathways downstream of rhodopsin activation. We propose that Arr1 mediates an endocytotic cell-survival activity, scavenging phosphorylated rhodopsin and thereby countering toxic Arr2/Rh1 accumulation; elimination of toxic Arr2/Rh1 in double mutants could thus rescue arr1 mutant photoreceptor degeneration

Unknotting numbers and triple point cancelling numbers of torus-covering knots

It is known that any surface knot can be transformed to an unknotted surface knot or a surface knot which has a diagram with no triple points by a finite number of 1-handle additions. The minimum number of such 1-handles is called the unknotting number or the triple point cancelling number, respectively. In this paper, we give upper bounds and lower bounds of unknotting numbers and triple point cancelling numbers of torus-covering knots, which are surface knots in the form of coverings over the standard torus $T$. Upper bounds are given by using $m$-charts on $T$ presenting torus-covering knots, and lower bounds are given by using quandle colorings and quandle cocycle invariants.Comment: 26 pages, 14 figures, added Corollary 1.7, to appear in J. Knot Theory Ramification

Effects of Surface Soil Removal on Dynamics of Dissolved Inorganic Nitrogen in a Snow-Dominated Forest

To clarify the effect of vegetation and surface soil removal on dissolved inorganic nitrogen (N) dynamics in a snow-dominated forest soil in northern Japan, the seasonal fluctuation of N concentrations in soil solution and the annual flux of N in soil were investigated at a treated site (in which surface soil, including understory vegetation and organic and A horizons, was removed) and control sites from July 1998 to June 2000. Nitrate (NO3–) concentration in soil solution at the treated site was significantly higher than that of the control in the no-snow period, and it was decreased by dilution from melting snow. The annual net outputs of NO3– from soil at the treated site and control sites were 257 and –12 mmol m–2 year–1, and about 57% of the net output at the treated site occurred during the snowmelt period. NO3– was transported from the upper level to the lower level of soil via water movement during late autumn and winter, and it was retained in soil and leached by melt water in early spring. Removing vegetation and surface soil resulted in an increase in NO3– concentration of soil solution, and snowmelt strongly affected the NO3– leaching from treated soil and the NO3– restoration process in a snow-dominated region

Computing the Characteristic Polynomial of a Finite Rank Two Drinfeld Module

Motivated by finding analogues of elliptic curve point counting techniques, we introduce one deterministic and two new Monte Carlo randomized algorithms to compute the characteristic polynomial of a finite rank-two Drinfeld module. We compare their asymptotic complexity to that of previous algorithms given by Gekeler, Narayanan and Garai-Papikian and discuss their practical behavior. In particular, we find that all three approaches represent either an improvement in complexity or an expansion of the parameter space over which the algorithm may be applied. Some experimental results are also presented

Myosin V, Rab11, and dRip11 direct apical secretion and cellular morphogenesis in developing Drosophila photoreceptors

Sensory neuron terminal differentiation tasks apical secretory transport with delivery of abundant biosynthetic traffic to the growing sensory membrane. We recently showed Drosophila Rab11 is essential for rhodopsin transport in developing photoreceptors and asked here if myosin V and the Drosophila Rab11 interacting protein, dRip11, also participate in secretory transport. Reduction of either protein impaired rhodopsin transport, stunting rhabdomere growth and promoting accumulation of cytoplasmic rhodopsin. MyoV-reduced photoreceptors also developed ectopic rhabdomeres inappropriately located in basolateral membrane, indicating a role for MyoV in photoreceptor polarity. Binary yeast two hybrids and in vitro protein–protein interaction predict a ternary complex assembled by independent dRip11 and MyoV binding to Rab11. We propose this complex delivers morphogenic secretory traffic along polarized actin filaments of the subcortical terminal web to the exocytic plasma membrane target, the rhabdomere base. A protein trio conserved across eukaryotes thus mediates normal, in vivo sensory neuron morphogenesis

Evolutionary plasticity of developmental gene regulatory network architecture

Sea stars and sea urchins evolved from a last common ancestor that lived at the end of the Cambrian, approximately half a billion years ago. In a previous comparative study of the gene regulatory networks (GRNs) that embody the genomic program for embryogenesis in these animals, we discovered an almost perfectly conserved five-gene network subcircuit required for endoderm specification. We show here that the GRN structure upstream and downstream of the conserved network kernel has, by contrast, diverged extensively. Mesoderm specification is accomplished quite differently; the Delta–Notch signaling system is used in radically distinct ways; and various regulatory genes have been coopted to different functions. The conservation of the conserved kernel is thus the more remarkable. The results indicate types of network linkage subject to evolutionary change. An emergent theme is that subcircuit design may be preserved even while the identity of genes performing given roles changes because of alteration in their cis-regulatory control systems