Divergence instabilities of nonuniformly prestressed travelling webs

The phenomenon of edge-buckling in an axially moving stretched thin elastic web is described as a nonstandard singularly perturbed bifurcation problem, which is then explored through the application of matched asymptotic techniques. Previous numerical work recently reported in the literature is re-evaluated in this context by approaching it through the lens of asymptotic simplifications. This allows us to identify two distinct regimes characterised by qualitative differences in the corresponding eigen-deformations; some simple approximate formulae for the critical eigenvalues are also proposed. The obtained analytical results capture the intricate relationship between the critical speeds, the background tension, and other relevant physical and geometric parameters that feature in the mathematical model

Wrinkling structures at the rim of an initially stratched circular thin plate subjected to transverse pressure

Short-wavelength wrinkles that appear on an initially stretched thin elastic plate under transverse loading are examined. As the degree of loading is increased so wrinkles appear and their structure at the onset of buckling takes on one of three distinct forms depending on the size of the imposed stretching. With relatively little stretching, the wrinkles sit off the rim of the plate at a location which is not known a priori, but which is determined via a set of consistency conditions. These take the form of constraints on the solutions of certain coupled nonlinear differential equations that are solved numerically. As the degree of stretching grows, so an asymptotic solution of the consistency conditions is possible which heralds the structure that governs a second regime. Now the wrinkle sits next to the rim where its detailed structure can be described by the solution of suitably scaled Airy equations. In each of these first two regimes the Föppl–von Kármán bifurcation equations remain coupled, but as the initial stretching becomes yet stronger the governing equations separate. Further use of singular-perturbation arguments allows us to identify the wavelength wrinkle which is likely to be preferred in practice

INFECTION WITH PASTEURELLA SPP. IN A NEW ZEALAND RABBIT COLONY

ABSTRACT The purpose of the research was to establish the etiology and to fight against the acute respiratory syndrome to New Zealand rabbits, of all ages to which the morbidity and mortality were high, from a farm with intensive breeding. Clinical 760 rabbits were examined, adults, young and new born raised in wire net cages in a closed stable, without draught. The necropsy examination was performed in laboratory on 57 dead rabbits with acute respiratory and also cultivations from trachea, lung, liver and spinal marrow were carried out. We used the bacterioscopic technique, cultivation on usual and selective media for Pasteurella, Mycoplasma and Streptococcus for isolation and identification of the micro-organisms present in the respiratory tract. Out of the 57 examined samples, 28 ones were positive and identified as Pasteurella spp., of which 21 were isolated from trachea, lung and liver and 7 from spinal marrow. Seventeen samples of the 28 examined ones contained both Pasteurella spp. and Mycoplasma spp. and 11 samples Pasteurella spp. and Streptococcus spp. also isolated and identified in trachea and lung. The antibiogram test used bio-discs with penicillin, amoxicillin, gentamicin, spectinomicin, oxytetracycline, erythromycin, enrofloxacin and cefaclor. The rabbits were divided into two groups: the first group was treated with enrofloxacin for 5 days, and the second group was treated with oxytetracycline for 5 days, both administered in drinking water. One day after the beginning of the treatment the rabbits got better and the mortality stopped after the fourth day of treatment

On the asymptotic reduction of a bifurcation equation for edge-buckling instabilities

Weakly clamped uniformly stretched thin elastic plates can experience edge buckling when subjected to a transverse pressure. This situation is revisited here for a circular plate, under the assumption of finite rotations and negligible bending stiffness in the pre-buckling range. The eigenproblem describing this instability is formulated in terms of two singularly perturbed fourth-order differential equations involving the non-dimensional bending stiffness ε>0. By using an extension of the asymptotic reduction technique proposed by Coman and Haughton (Acta Mech 55:179–200, 2006), these equations are formally reduced to a simple second-order ordinary differential equation in the limit ε→0+. It is further shown that the predictions of this reduced problem are in excellent agreement with the direct numerical simulations of the original bifurcation equations

Pluripolarity of Graphs of Denjoy Quasianalytic Functions of Several Variables

In this paper we prove pluripolarity of graphs of Denjoy quasianalytic functions of several variables on the spanning se

Increasing seedstock production of domesticated giant tiger prawns

Given the rationale that pond systems are likely the most cost-effective system for large-scale production of P. monodon broodstock, this project aimed to determine whether pond-rearing poses a significant risk for broodstock production. The gross reproductive development of males reared in low-density broodstock ponds was found comparable to sibling males reared in controlled-environment tanks. Furthermore,none of the environmental ‘stressors’ and dietary manipulations examined impacted on male reproductive tract development. Thus, within the boundaries of the parameters tested, we can state that rearing of male broodstock in low-density ponds does not pose inherent risks of gross reproductive tract impairment. Given the typically lower costs of constructing and managing broodstock in large-scale pond systems, as compared to smaller raceway and tank systems, the incorporation of a pond-rearing phase in broodstock production could clearly increase cost-effectiveness of broodstock production at a commercial scale