On a foundation for Cournot equilibrium

We show in the context of a bilateral oligopoly where all agents are allowed to behave strategically the unexpected result that when the number of buyers becomes large the outcomes in a strategic market game do not converge to those at the Cournot equilibrium. However, convergence to Cournot outcomes is restored if the game is sequential: sellers move simultaneously as do buyers, but the former always move before the latter. This suggests that the ability to commit to supply decisions is an essential feature of Cournot equilibrium

Long subcutaneous tunnelling reduces infection rates in paediatric external ventricular drains

Purpose The aim of this study is to report the efficacy of long subcutaneous tunnelling of external ventricular drains in reducing rates of infection and catheter displacement in a paediatric population. Methods In children requiring external ventricular drainage, a long-tunnelled drain was placed and managed according to a locally agreed guideline. End points were novel CSF infection incurred during the time of drainage and re-operation to re-site displaced catheters. Data were compared to other published series. Results One hundred eighty-one long-tunnelled external ventricular drains (LTEVDs) were inserted. The mean age was 6.6 years (range 0-15.5 years). Reasons for insertion included intraventricular haemorrhage (47 %), infection (27 %), tumour-related hydrocephalus (7.2 %), as a temporising measure (17 %) and trauma (2.2 %). The overall new infection rate for LTEVD was 2.76 %. If the 48 cases where LTEVDs were inserted to treat an existing infection are excluded, the infection rate was 3.8 % (5/133). The mean duration of insertion was 10 days (range 0-42 days). Four LTEVDs (2.2 %) were inadvertently dislodged, requiring reinsertion. Thirteen patients required removal of EVD alone.There was a significant difference (p < 0.05) when comparing our infection rate to 14 publications of infection rates in short-tunnelled EVDs; however, there was no difference when comparing our data to three publications using LTEVDs. Conclusion The use of an antibiotic-impregnated LTEVD, managed according to a predefined guideline, is associated with significantly reduced infection and displacement rates when compared with contemporary series. It is suggested that this reduction is of both clinical and economic benefits

Grasses and the resource availability hypothesis: the importance of silica-based defences

The resource availability hypothesis (RAH) predicts that allocation of resources to anti-herbivore defences differs between species according to their growth rate. We tested this hypothesis by assessing the growth and defence investment strategies of 18 grass species and comparing them against vole feeding preferences. In addition, we assessed the effectiveness of silica, the primary defence in many grasses, in influencing vole feeding behaviour. Across species, we found that there was a strong negative relationship between the overall investment in defence and growth rate, thus supporting predictions of the RAH. However, no such relationship was found when assessing the various individual anti-herbivore defences, suggesting that different grass species show significant variation in their relative investment in strategies such as phenolic concentration, silica concentration and leaf toughness. Silica was the most influential defensive factor in determining vole feeding preference. Experimentally induced increases in leaf silica concentration deterred vole feeding in three of the five species tested, and altered feeding preference ranks between species. The strong positive relationship between silica concentration and leaf abrasiveness, when assessed both within and between species, suggests that increased abrasiveness is the mechanism by which silica deters feeding. Although grasses are often considered to be tolerant of herbivore damage rather then defended against it, they do follow predictions of defence allocation strategy based on their growth rates, and this affects the feeding behaviour of generalist grass-feeding herbivores

Moments of inertia of several airplanes

This paper, which is the first of a series presenting the results of such measurements, gives the momental ellipsoids of ten army and naval biplanes and one commercial monoplane. The data were obtained by the use of a pendulum method, previously described. The moments of inertia are expressed in coefficient as well as in dimensional form, so that those for airplanes of widely different weights and dimensions can be compared

Flight Tests to Determine the Effect of a Fixed Auxiliary Airfoil on the Lift and Drag of a Parasol Monoplane

Comparative flight tests were made with a small parasol monoplane in which the aerodynamic characteristics of the airplane were determined with the normal wing and with an auxiliary airfoil installed

The Doha Talks and the Bargaining Surplus in Agriculture

The Doha Round has been slow to achieve a reduction in the level of agricultural protection. This remains the case notwithstanding the substantial economic benefits that would arise from a more liberal agricultural trading regime. We provide one explanation for this slowness using a simple bargaining model. We demonstrate that the bargaining countries received a substantial fiscal gain from reducing government expenditures in the run-up to the Uruguay Round. This fiscal pressure was sufficient to block rent seekers who wanted farm payments to continue. Since the Uruguay Round these fiscal constraints have been reduced and the same pressure to reach a bargain and control rent-seeking behaviour is not present in the Doha Round.Doha Round, rent seeking, bargaining, International Relations/Trade,

Screening of the transcriptional regulatory regions of vascular endothelial growth factor receptor 2 (VEGFR2) in amyotrophic lateral sclerosis

Background Vascular endothelial growth factor (VEGF) has neurotrophic activity which is mediated by its main agonist receptor, VEGFR2. Dysregulation of VEGF causes motor neurone degeneration in a mouse model of amyotrophic lateral sclerosis (ALS), and expression of VEGFR2 is reduced in motor neurones and spinal cord of patients with ALS. Methods We have screened the promoter region and 4 exonic regions of functional significance of the VEGFR2 gene in a UK population of patients with ALS, for mutations and polymorphisms that may affect expression or function of this VEGF receptor. Results No mutations were identified in the VEGFR2 gene. We found no association between polymorphisms in the regulatory regions of the VEGFR2 gene and ALS. Conclusion Mechanisms other than genetic variation may downregulate expression or function of the VEGFR2 receptor in patients with ALS

Confidence regions for variance ratios in variance components models

Statistical mechanics for constructing confidence intervals for variance ratios in balanced and unbalanced experimental design

Rumpel-Leede phenomenon in a hypertensive patient due to mechanical trauma: a case report.

In this report, we present an interesting case of a patient with Rumpel-Leede phenomenon, a rare occurrence that can result in significant delays in medical treatment. This phenomenon is characterized by the presence of a petechial rash that results from acute dermal capillary rupture. In our patient, it occurred secondary to raised pressure in the dermal vessels caused by repeated inflation of a sphygmomanometer cuff. Contributory factors in Rumpel-Leede phenomenon include prevalent conditions such as diabetes mellitus, hypertension, thrombocytopenia, chronic steroid use, antiplatelets, and anticoagulants.A 58-year-old Russian woman with diabetes and hypertension presented to our hospital with a non-ST elevation myocardial infarction, and she subsequently developed a petechial rash on her distal upper limbs. A vasculitic screen was performed, with normal results.Given the timing and distribution of the rash, it was felt that this was an example of Rumpel-Leede phenomenon in a susceptible individual. This is an important diagnosis to be aware of in patients with vascular risk factors presenting for acute medical care who subsequently develop a petechial rash

Tensor distributions on signature-changing space-times

Irregularities in the metric tensor of a signature-changing space-time suggest that field equations on such space-times might be regarded as distributional. We review the formalism of tensor distributions on differentiable manifolds, and examine to what extent rigorous meaning can be given to field equations in the presence of signature-change, in particular those involving covariant derivatives. We find that, for both continuous and discontinuous signature-change, covariant differentiation can be defined on a class of tensor distributions wide enough to be physically interesting.Comment: 9 pages, LaTeX 2.0