The effect of environmental stressors on the development and behaviour of larval Oryzias latipes

Elevated water temperature and dissolved carbon dioxide (CO2) are two environmental stressors that freshwater organisms face in the Anthropocene. Larval fishes are particularly susceptible to elevation in water parameters, as they are often confined to rearing habitats where temperature and CO2 are nearing species-specific maxima. In this study, 240 freshwater Japanese medaka (Oryzias latipes) eggs were exposed to either control conditions (27˚C, ~ 500 μatm pCO2), elevated water temperature (36˚C), elevated CO2 (~1500 μatm pCO2) or both elevated temperature and CO2 (36˚C, ~1500 μatm pCO2). Exposures were applied either during the early, middle or late developmental stages and the morphological and behavioural data was collected ten days post-hatch. I predicted that elevated temperature and CO2 would decrease hatching success, and produce abnormalities in the swim bladder, spine or heart. In addition, I predicted that fish exposed to the stressors would show a change in swimming behaviour. Of the behavioural parameters observed, a significant difference was found in the distance travelled among the larval fish exposed to the treatments. There was no significant change between treatments or time intervals for hatching success, length or morphology. As rising CO2 and warming are likely to have a consequential impact on freshwater species, further research dedicated to understanding the ramification of climate-induced stressors is imperative.Honours Thesis Course, Department of Biolog

The metric dimension and metric independence of a graph

A vertex x of a graph G resolves two vertices u and v of G if the distance from x to u does not equal the distance from x to v. A set S of vertices of G is a resolving set for G if every two distinct vertices of G are resolved by some vertex of S. The minimum cardinality of a resolving set for G is called the metric dimension of G. The problem of nding the metric dimension of a graph is formulated as an integer pro- gramming problem. It is shown how a relaxation of this problem leads to a linear programming problem and hence to a fractional version of the metric dimension of a graph. The linear programming dual of this problem is considered and the solution to the corresponding integer programming problem is called the metric independence of the graph. It is shown that the problem of deciding whether, for a given graph G, the metric dimension of G equals its metric independence is NP- complete. Trees with equal metric dimension and metric independence are characterized. The metric independence number is established for various classes of graphs.Preprin

A family of formulas with reversal of high avoidability index

We present an infinite family of formulas with reversal whose avoidability index is bounded between 4 and 5, and we show that several members of the family have avoidability index 5. This family is particularly interesting due to its size and the simple structure of its members. For each k ∈ {4,5}, there are several previously known avoidable formulas (without reversal) of avoidability index k, but they are small in number and they all have rather complex structure.http://dx.doi.org/10.1142/S021819671750024

Attainable lengths for circular binary words avoiding k-powers

We show that binary circular words of length n avoiding 7/3+ powers exist for every sufficiently large n. This is not the case for binary circular words avoiding k+ powers with k < 7/3https://projecteuclid.org/download/pdf_1/euclid.bbms/113379334

Avoidability index for binary patterns with reversal

For every pattern $p$ over the alphabet $\{x,y,x^R,y^R\}$, we specify the least $k$ such that $p$ is $k$-avoidable.Comment: 15 pages, 1 figur

On the Andrews congruence for the Fibonacci quotient

We show that a congruence discovered by George E. Andrews in 1969 for the Fibonacci quotient directly implies a simpler congruence found by Hugh C. Williams in 1991

Binary words avoiding xx^Rx and strongly unimodal sequences

In previous work, Currie and Rampersad showed that the growth of the number of binary words avoiding the pattern xxx^R was intermediate between polynomial and exponential. We now show that the same holds for the growth of the number of binary words avoiding the pattern xx^Rx. Curiously, the analysis for xx^Rx is much simpler than that for xxx^R. We derive our results by giving a bijection between the set of binary words avoiding xx^Rx and a class of sequences closely related to the class of "strongly unimodal sequences."Comment: 4 page

Horse and Herald: Posidippus' Equestrian Angelia

Posidippus’ epigrams for equestrian victors (the Hippika, AB 71–88) build on epinician convention by maintaining the central role of the herald’s proclamation— the angelia—in the representation of athletic achievement. In a few of these epigrams, however, Posidippus embeds the horse itself in postvictory rituals. For example, the horse brings the crown to the victor, replacing the figure of the herald who announced and crowned victors; or, in a narrative of the race’s aftermath, the horse, incredibly, chooses the victor. Posidippus’ horses, therefore, act as causal agents for the glory of their owners, and his detailed descriptions transform the horse from flesh-and-blood equine to everlasting (literary) monument. Les épigrammes de Posidippe sur les victoires équestres (les Hippiques, 71-88 A.-B.) s’appuient sur une convention poétique propre aux épinicies qui maintient le rôle de la proclamation du héraut – l’angelia – dans la représentation de la réussite athlétique. Cependant, dans quelques-unes de ces épigrammes, Posidippe intègre le cheval lui-même au rituel marquant la victoire. Par exemple, le cheval apporte la couronne au vainqueur en remplacement de la figure du héraut qui annonce et couronne les vainqueurs ; ou encore, dans le récit de l’après-course, le cheval choisit, de façon surprenante, le vainqueur. Les chevaux de Posidippe interviennent donc en tant qu’agents causaux dans la gloire de leur propriétaire. Ses descriptions détaillées transforment ainsi l’être de chair et de sang qu’est le cheval en un monument (littéraire) éternel.https://www.utpjournals.press/doi/full/10.3138/mous.16.3.00