A Process Calculus for Spatially-explicit Ecological Models

We propose PALPS, a Process Algebra with Locations for Population Systems. PALPS allows us to produce spatially-explicit, individual-based models and to reason about their behavior. Our calculus has two levels: at the first level we may define the behavior of an individual of a population while, at the second level, we may specify a system as the collection of individuals of various species located in space, moving through their life cycle while changing their location, if they so wish, and interacting with each other in various ways such as preying on each other. Furthermore, we propose a probabilistic temporal logic for reasoning about the behavior of PALPS processes. We illustrate our framework via models of dispersal in metapopulations.Comment: In Proceedings MeCBIC 2012, arXiv:1211.347

Interactions between piperonyl butoxide analogues and metabolic enzymes conferring insecticide resistance

The insecticide synergist, piperonyl butoxide (PBO), has been used to reduce resistance factors and to characterise metabolic resistance resulting from mixed function oxidases (MFOs). Studies have also shown that PBO can interact with resistance-associated esterases. It is well-documented that the mechanism by which PBO inhibits P450s is the interaction of the methylenedioxyphenyl (MDP) moiety of PBO molecule with the haem moiety of the enzyme. To investigate the interactions between PBO and esterases, a structure activity relationship (SAR) study was carried out using analogues of PBO and E4, a resistanceassociated esterase from the peach-potato aphid Myzus persicae. Results indicate that the polyether and the alkyl chain were fundamentally important in this interaction. Removing one oxygen atom from the MDP moiety of PBO did not affect the binding affinity, but increased affinities resulted from the replacement of the polyether with an alkynyl ether chain or by increasing the length of the alkyl chain. An analogue, EN 16/5-1, that retains the ability to interact with esterases but loses the ability to act on P450s, due to a modification to the MDP moiety, was used in conjunction with PBO to facilitate characterisation of metabolic resistance in M. persicae and pollen beetle Meligethes aeneus. Selected analogues of PBO containing the alkynyl ether side chain exhibited high synergistic effects in vivo and were found to be potent inhibitors of O-deethylation of 7-ethoxycoumarin when tested against pyrethroid resistant M. aeneus. The capability of some of the analogues to act as insecticide synergists was investigated in vivo against two M. persicae clones possessing different metabolic resistance profiles. Finally, the potential of PBO analogues to provide potent and/or specific synergism to overcome insecticide resistance and reduce insecticide titre applied to crops is considered

Active surveillance of prostate cancer: a questionnaire survey of urologists, clinical oncologists and urology nurse specialists across three cancer networks in the United Kingdom

Abstract Background Active surveillance is considered a mainstream strategy in the management of patients with low-risk prostate cancer. A mission-critical step in implementing a robust active surveillance program and plan its resource and service requirements, is to gauge its current practice across the United Kingdom. Furthermore it is imperative to determine the existing practices in the context of the recommendations suggested by the recent National Institute for Health and Clinical Excellence guidance on active surveillance of prostate cancer. Methods An internet questionnaire was circulated to urologists, clinical oncologists and urology nurse specialists across three geographically distinct cancer networks. Twenty five questions across four domains were assessed. (i) hospital resources (staff and clinical areas) utilised for active surveillance (ii) enrolment criteria (iii) follow up (iv) criteria that trigger conversion to active treatment. Results We received 35 responses, 20 of which were from urologists. The survey data suggests that there is marked heterogeneity in enrolment criteria with patients having features of intermediate-risk prostate cancer often recruited into Active Surveillance programs. Only 60 % of our respondents use multiparametric MRI routinely to assess patient suitability for active surveillance. In addition, marked variation exists in how patients are followed up with regard to PSA testing intervals and timing of repeat biopsies. Only 40 % undertake a repeat biopsy at 12 months. Tumour upgrading on repeat biopsy, an increase in tumour volume or percentage of core biopsies involved would prompt a recommendation for treatment amongst most survey respondents. In addition allocation of resources and services for active surveillance is poor. Currently there are no dedicated active surveillance clinics, which are well-structured, -resourced and -supported for regular patient counselling and follow up. Conclusion This variability in enrolment criteria and follow up is also demonstrated in international and national series of active surveillance. Resources are not currently in place across the UK to support an active surveillance program and a national discussion and debate to plan resources is much required so that it can become a mainstream therapeutic strategy

Comparative Oncologic and Toxicity Outcomes of Salvage Radical Prostatectomy Versus Nonsurgical Therapies for Radiorecurrent Prostate Cancer: A Meta-Regression Analysis.

CONTEXT: In the absence of randomised controlled trials comparing the oncologic, toxicity, and functional outcomes of salvage radical prostatectomy (SRP), salvage high-intensity focused ultrasound (SHIFU), salvage brachytherapy (SBT), and salvage cryotherapy (SCT), controversy exists as to the optimal salvage modality in radiorecurrent prostate cancer. OBJECTIVE: We carried out a meta-regression analysis to determine whether there is a difference in oncologic, toxicity, and functional outcomes using data from original publications of salvage modalities in the postradiation setting. EVIDENCE ACQUISITION: We performed a systematic review of PubMed/Medline citations according to the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) statement. We included 63 articles in the analysis (25 on SRP, 8 on SHIFU, 16 on SCT, 14 on SBT). EVIDENCE SYNTHESIS: Median values of the following variables were extracted from each study: patient age, length of follow-up, prostate-specific antigen (PSA) before radiotherapy (RT), PSA before salvage therapy, Gleason score before RT, and time interval between RT and salvage therapy. Functional, toxicity, and oncologic outcomes were measured according to rates of impotence, incontinence, fistula formation, urethral strictures, and biochemical recurrence. Meta-regression adjusting for confounders found no significant difference in oncologic outcomes between SRP and nonsurgical salvage modalities. SBT, SCT, and SHIFU appeared to have better continence outcomes than SRP. No significant difference in toxicity outcomes between modalities was found, although limitations such as reporting, selection, and publication bias and between-study heterogeneity must also be considered with these conclusions. CONCLUSIONS: Oncologic outcomes are comparable for SRP and all three nonsurgical salvage modalities. We found no significant differences in toxicity outcomes among modalities; however, SRP appears to be associated with worse rates of urinary incontinence than SBT, SCT, and SHIFU. PATIENT SUMMARY: We performed a meta-regression analysis to compare oncologic, functional, and toxicity outcomes between salvage radical prostatectomy and nonsurgical salvage modalities. Oncologic and toxicity outcomes appear to be similar; however, all nonsurgical salvage modalities may be associated with better continence outcomes.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.euf.2015.09.00

Controlling Reversibility in Reversing Petri Nets with Application to Wireless Communications

Petri nets are a formalism for modelling and reasoning about the behaviour of distributed systems. Recently, a reversible approach to Petri nets, Reversing Petri Nets (RPN), has been proposed, allowing transitions to be reversed spontaneously in or out of causal order. In this work we propose an approach for controlling the reversal of actions of an RPN, by associating transitions with conditions whose satisfaction/violation allows the execution of transitions in the forward/reversed direction, respectively. We illustrate the framework with a model of a novel, distributed algorithm for antenna selection in distributed antenna arrays.Comment: RC 201