Defensive Adaptations and Natural Enemies of a Case-Bearing Beetle, Exema canadensis (Coleoptera: Chrysomelidae)

The larval habit of constructing and carrying a portable case has evolved many times in the Holometabola. It is a widespread trait of the Trichoptera and Lepidoptera (e.g. the Coleophoridae and Psychidae). Among the Coleoptera, casebearing is found in four related subfamilies of the Chrysomelidae, the so-called camptosomates: Clytrinae, Cryptocephalinae, Chlamisinae, and Lamprosomatinae (B6ving and Craighead 1931). The larval case of many insects is thought to function primarily in defense by providing armor or camouflage (Otto and Svensson 1980). Here we describe the uses of the case and other defenses in a chlamisine beetle, Exerna canadensis Pierce, and speculate briefly on the evolution and consequences of the case-bearing habit. The genus Exema Lacordaire contains nine species in North America (Karren 1966). All of the species appear to be univoltine and to feed on a fairly restricted range of herbaceous or shrubby genera in the Asteraceae (Jenks 1940; Karren 1966, 1972). In central New York E. canadensis is commonly found on goldenrods (Sol# dago spp.) and asters (Aster spp.). Its life cycle was summarized by Messina and Root (1980). Le Sage (1982) recently described the immature stages

Care For Pastors: Learning From Clergy and Their Spouses

Pastors and their spouses face unique challenges because of the nature of pastoral work, and yet most manage these challenges successfully. Five studies are presented which help distinguish between intrapersonal, family, and community forms of care. Pastors rely heavily on intrapersonal forms of coping such as spiritual devotion, hobbies, exercise, and taking time away from work. The marriage relationship is also quite important for most clergy and spouses. Relationships outside the immediate family are not commonly identified as coping resources. Implications are discussed

Multi-scale Renormalisation Group Improvement of the Effective Potential

Using the renormalisation group and a conjecture concerning the perturbation series for the effective potential, the leading logarithms in the effective potential are exactly summed for $O(N)$ scalar and Yukawa theories.Comment: 19 pages, DIAS STP 94-09. Expanded to check large N limit, typo's corrected, to appear in Phys Rev

Systematic 1/N1/N corrections for bosonic and fermionic vector models without auxiliary fields

In this paper, colorless bilocal fields are employed to study the large $N$ limit of both fermionic and bosonic vector models. The Jacobian associated with the change of variables from the original fields to the bilocals is computed exactly, thereby providing an exact effective action. This effective action is shown to reproduce the familiar perturbative expansion for the two and four point functions. In particular, in the case of fermionic vector models, the effective action correctly accounts for the Fermi statistics. The theory is also studied non-perturbatively. The stationary points of the effective action are shown to provide the usual large $N$ gap equations. The homogeneous equation associated with the quadratic (in the bilocals) action is simply the two particle Bethe Salpeter equation. Finally, the leading correction in $1\over N$ is shown to be in agreement with the exact $S$ matrix of the model.Comment: 24 pages, uses REVTEX macros. Replaced with final version to appear in Phys. Rev.

The Kramers equation simulation algorithm II. An application to the Gross-Neveu model

We continue the investigation on the applications of the Kramers equation to the numerical simulation of field theoretic models. In a previous paper we have described the theory and proposed various algorithms. Here, we compare the simplest of them with the Hybrid Monte Carlo algorithm studying the two-dimensional lattice Gross-Neveu model. We used a Symanzik improved action with dynamical Wilson fermions. Both the algorithms allow for the determination of the critical mass. Their performances in the definite phase simulations are comparable with the Hybrid Monte Carlo. For the two methods, the numerical values of the measured quantities agree within the errors and are compatible with the theoretical predictions; moreover, the Kramers algorithm is safer from the point of view of the numerical precision.Comment: 20 pages + 1 PostScript figure not included, REVTeX 3.0, IFUP-TH-2

Three-Dimensional Quantum Percolation Studied by Level Statistics

Three-dimensional quantum percolation problems are studied by analyzing energy level statistics of electrons on maximally connected percolating clusters. The quantum percolation threshold \pq, which is larger than the classical percolation threshold \pc, becomes smaller when magnetic fields are applied, i.e., \pq(B=0)>\pq(B\ne 0)>\pc. The critical exponents are found to be consistent with the recently obtained values of the Anderson model, supporting the conjecture that the quantum percolation is classified onto the same universality classes of the Anderson transition. Novel critical level statistics at the percolation threshold is also reported.Comment: to appear in the May issue of J. Phys. Soc. Jp

Teachers as writers: a systematic review

This paper is a critical literature review of empirical work from 1990-2015 on teachers as writers. It interrogates the evidence on teachers’ attitudes to writing, their sense of themselves as writers and the potential impact of teacher writing on pedagogy or student outcomes in writing. The methodology was carried out in four stages. Firstly, educational databases keyword searches located 438 papers. Secondly, initial screening identified 159 for further scrutiny, 43 of which were found to specifically address teachers’ writing identities and practices. Thirdly, these sources were screened further using inclusion/exclusion criteria. Fourthly, the 22 papers judged to satisfy the criteria were subject to in-depth analysis and synthesis. The findings reveal that the evidence base in relation to teachers as writers is not strong, particularly with regard to the impact of teachers’ writing on student outcomes. The review indicates that teachers have narrow conceptions of what counts as writing and being a writer and that multiple tensions exist, relating to low self-confidence, negative writing histories, and the challenge of composing and enacting teacher and writer positions in school. However, initial training and professional development programmes do appear to afford opportunities for reformulation of attitudes and sense of self as writer

Exact and approximate dynamics of the quantum mechanical O(N) model

We study a quantum dynamical system of N, O(N) symmetric, nonlinear oscillators as a toy model to investigate the systematics of a 1/N expansion. The closed time path (CTP) formalism melded with an expansion in 1/N is used to derive time evolution equations valid to order 1/N (next-to-leading order). The effective potential is also obtained to this order and its properties areelucidated. In order to compare theoretical predictions against numerical solutions of the time-dependent Schrodinger equation, we consider two initial conditions consistent with O(N) symmetry, one of them a quantum roll, the other a wave packet initially to one side of the potential minimum, whose center has all coordinates equal. For the case of the quantum roll we map out the domain of validity of the large-N expansion. We discuss unitarity violation in the 1/N expansion; a well-known problem faced by moment truncation techniques. The 1/N results, both static and dynamic, are also compared to those given by the Hartree variational ansatz at given values of N. We conclude that late-time behavior, where nonlinear effects are significant, is not well-described by either approximation.Comment: 16 pages, 12 figrures, revte