Variation of prey responses to cues from a mesopredator and an apex predator

© 2014 Ecological Society of Australia 39 7 November 2014 10.1111/aec.12138 Original Articles Original Article © 2014 The Authors. Austral Ecology. Detection and avoidance of predator cues can be costly, so it is important for prey to balance the benefits of gaining food against the costs of avoiding predators. Balancing these factors becomes more complicated when prey are threatened by more than one type of predator. Hence, the ability to recognize species-specific predator odours and prioritize behaviours according to the level of risk is essential for survival. We investigated how rock rats, Zyzomys spp. modify their foraging behaviour and giving-up density (GUD) in the presence of an apex predator, the dingo Canis dingo, a mesopredator, the northern quoll Dasyurus hallucatus, a herbivore, the rock wallaby Petrogale brachyotis as a pungency control and water as a procedural control. Both dingoes and quolls consume rock rats, but because quolls can enter small crevices inhabited by rock rats, they pose a greater threat to rock rats than dingoes. Rock rats demonstrated a stronger avoidance to quoll odour than dingo odour, and no avoidance of the pungency control (rock wallaby) and the procedural control (water). GUD values declined significantly over the duration of the study, but did not differ between odour treatments. Our results support the hypothesis that prey vary behaviour according to perceived predator threat, and show stronger responses to potentially more dangerous predators

What is the probability that a random integral quadratic form in nn variables has an integral zero?

We show that the density of quadratic forms in $n$ variables over $\mathbb Z_p$ that are isotropic is a rational function of $p$, where the rational function is independent of $p$, and we determine this rational function explicitly. When real quadratic forms in $n$ variables are distributed according to the Gaussian Orthogonal Ensemble (GOE) of random matrix theory, we determine explicitly the probability that a random such real quadratic form is isotropic (i.e., indefinite). As a consequence, for each $n$, we determine an exact expression for the probability that a random integral quadratic form in $n$ variables is isotropic (i.e., has a nontrivial zero over $\mathbb Z$), when these integral quadratic forms are chosen according to the GOE distribution. In particular, we find an exact expression for the probability that a random integral quaternary quadratic form has an integral zero; numerically, this probability is approximately $98.3\%$.Comment: 17 pages. This article supercedes arXiv:1311.554

A preclinical evaluation of the PI3K alpha/delta dominant inhibitor BAY 80-6946 in HER2-positive breast cancer models with acquired resistance to the HER2-targeted therapies trastuzumab and lapatinib.

The PI3K pathway is a key mechanism of trastuzumab resistance, but early attempts to indirectly target this pathway with mTOR inhibitors have had limited success. We present the results of a preclinical study of the selective alpha/delta isoform dominant PI3K inhibitor BAY 80-6946 tested alone and in combination with HER2-targeted therapies in HER2-positive cell lines, including models with acquired resistance to trastuzumab and/or lapatinib. A panel of HER2-positive breast cancer cells were profiled for their mutational status using Sequenom MassARRAY, PTEN status by Western blot, and anti-proliferative response to BAY 80-6946 alone and in combination with the HER2-targeted therapies trastuzumab, lapatinib and afatinib. Reverse phase protein array was used to determine the effect of BAY 80-6946 on expression and phosphorylation of 68 proteins including members of the PI3K and MAPK pathways. The Boyden chamber method was used to determine if BAY 80-6946 affected cellular invasion and migration. BAY 80-6946 has anti-proliferative and anti-invasive effects when used alone in our panel of cell lines (IC50s 3.9-29.4 nM). BAY 80-6946 inhibited PI3K signalling and was effective in cells regardless of their PI3K, P53 or PTEN status. The combination of HER2-targeted therapies and BAY 80-6946 inhibited growth more effectively than either therapy used alone (with clear synergism in many cases), and can restore sensitivity to trastuzumab and lapatinib in cells with acquired resistance to either trastuzumab and/or lapatinib. The addition of BAY 80-6946 to HER2-targeted therapy could represent an improved treatment strategy for patients with refractory metastatic HER2-positive breast cancer, and should be considered for clinical trial evaluation

Elliptic Curves over Real Quadratic Fields are Modular

We prove that all elliptic curves defined over real quadratic fields are modular.Comment: 38 pages. Magma scripts available as ancillary files with this arXiv versio

Modular symbols in Iwasawa theory

This survey paper is focused on a connection between the geometry of $\mathrm{GL}_d$ and the arithmetic of $\mathrm{GL}_{d-1}$ over global fields, for integers $d \ge 2$. For $d = 2$ over $\mathbb{Q}$, there is an explicit conjecture of the third author relating the geometry of modular curves and the arithmetic of cyclotomic fields, and it is proven in many instances by the work of the first two authors. The paper is divided into three parts: in the first, we explain the conjecture of the third author and the main result of the first two authors on it. In the second, we explain an analogous conjecture and result for $d = 2$ over $\mathbb{F}_q(t)$. In the third, we pose questions for general $d$ over the rationals, imaginary quadratic fields, and global function fields.Comment: 43 page

The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration

This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened

Computations in non-commutative Iwasawa theory

We study special values of L-functions of elliptic curves over Q twisted by Artin representations that factor through a false Tate curve extension $Q(\mu_p^\infty,\sqrt[p^\infty]{m})/Q$. In this setting, we explain how to compute L-functions and the corresponding Iwasawa-theoretic invariants of non-abelian twists of elliptic curves. Our results provide both theoretical and computational evidence for the main conjecture of non-commutative Iwasawa theory.Comment: 60 pages; with appendix by John Coates and Ramdorai Sujath