Dynamical complexities in a tri-trophic hybrid food chain model with Holling type II and Crowley–Martin functional responses

We study how predator behavior influences community dynamics of predatorprey systems. It turns out that predator behavior plays a dominant role in community dynamics. The hybrid model studied in this paper reveals that period-doubling and period-doubling reversals can generate short-term recurrent chaos (STRC), which mimics chaotic dynamics observed in natural populations. STRC manifests itself when deterministic changes in a system parameter interrupt chaotic behavior at unpredictable intervals. Numerical results reinforce an earlier suggestion that period-doubling reversals could control chaotic dynamics in ecological models. In ecological terms, the prey and intermediate predator populations may go to extinction in the event of a catastrophe. The top predator is always a survivor. In contrast to this, this is not the case when the constituent populations are interacting through Holling type II functional response. Even this top predator can go to extinction in the event of such catastrophes

A stable isotopic study of the diet of Potamonautes sidneyi (Brachyura: Potamonautidae) in two coastal lakes of the iSimangaliso Wetland Park, South Africa

Potamonautes sidneyi Rathbun 1904, is a dominant freshwater crab in KwaZulu-Natal, South Africa. Recent flood events in the iSimangaliso Wetland Park have allowed a substantial range expansion of this species, including previously hypersaline and desiccated areas. A stable isotope study was conducted to examine the feeding habits of the populations from Lake Sibaya and Mpophomeni Stream, two contrasting sites in the iSimangaliso Wetland Park. Juveniles from Mpophomeni Stream were more depleted in δ13C and more enriched in δ15N compared to adults, indicating a more carnivorous diet and higher trophic position. A general shift in diet was observed at both sites, with consumption of aquatic invertebrates and sedimentary organic matter more prevalent in the wet summer months, while greater proportions of detritus and microphytobenthos were consumed in autumn/winter. No significant difference was observed between adults from the two sites despite the abiotic variations. The species appears to play a complex role in the trophic web, by acting as an intermediate consumer facilitating the flow of nutrients across levels and by breaking down decomposing organic matter, allowing for rapid recycling of nutrients within its ecosystem.Keywords: diet, trophic role, stable isotopes, freshwater, brachyurans, opportunistic feeder

Some aspects of animal behavior and community dynamics

We simulate the dynamical behavior of a few two - dimensional predator - prey systems in two - dimensional parameter spaces to gain insight into how functional responses affect community dynamics. The insight gained helps us design three dimensional systems. We construct models for a few ecosystems with three species and study them using computer simulations. The models have been developed by linking food chains which have both kinds of predators: specialist as well as generalist. The linking functions are weakly non-linear. The three dimensional model ecosystems have sexually reproducing top - predators. We perform extensive simulations to figure out dynamics of dynamical possibilities caused by changes in animal behavior. The animals change the foraging strategies and behave differently in different environments. At the end of the paper, we examine how diseases can govern transitions in meandering of dynamical models in bounded volume of their phase spaces

Electrochemistry education in the twenty-first century: the current landscape in the UK, challenges and opportunities

Electrochemistry education of future researchers is crucial if we are to decarbonise economies and reach targets for net zero, and this arguably begins with education in electrochemistry within undergraduate degrees. This paper reviews the teaching of electrochemistry in UK universities at the undergraduate degree level. We review where and how electrochemical concepts are introduced into chemistry, chemical engineering and materials science programmes. We provide some motivation for this review, which was stimulated by discussions from a workshop on the ‘Future of Fundamental Electrochemistry Research in the UK’, held in 2022. We summarise briefly how consensus on UK degree programme course content has been reached and inconsistencies that remain. Electrochemistry curriculum content from a convenience sample of UK universities, and disciplines, has been collected and is summarised, with a reflection on some trends. Finally, we present some implications for policy. A roadmap is suggested to ensure that the teaching of electrochemical fundamentals is addressed in the curriculum at an appropriate level to underpin the many technically relevant applications of electrochemistry that graduates will encounter in their further education or employment

General Practitioners' views on the provision of nicotine replacement therapy and bupropion.

BACKGROUND: Nicotine replacement therapies (NRT) and a new drug, bupropion, are licensed in several countries as aids to smoking cessation. General practitioners (GPs) play a crucial role in recommending or prescribing these medications. In the UK there has been discussion about whether the medications should be reimbursable by the National Health Service (NHS). This study assessed English GPs' attitudes towards reimbursement of NRT and bupropion. METHODS: Postal survey of a randomly selected national sample of GPs; 376 GPs completed the questionnaire after one reminder; effective response rate: 53%. There was no difference between the responses of GPs who responded to the initial request and those who responded only after a reminder suggesting minimal bias due to non-response. RESULTS: Attitudes of GPs were remarkably divided on most issues relating to the medications. Forty-three percent thought that bupropion should not be on NHS prescription while 42% thought that it should be (15% did not know); Fifty percent thought that NRT should not be on NHS prescription while 42% thought it should be (8% did not know). Requiring that smokers attend behavioural support programmes to be eligible to receive the medications on NHS prescription made no appreciable difference to the GPs' views. GPs were similarly divided on whether having the medications reimbursable would add unacceptably to their workload or offer a welcome opportunity to discuss smoking with their patients. A principal components analysis of responses to the individual questions on NRT and bupropion revealed that GPs' attitudes could be understood in terms of a single 'pro-con' dimension accounting for 53% of the total variance which made no distinction between the two medications. CONCLUSIONS: GPs in England appear to be divided in their attitudes to medications to aid smoking cessation and appear not to discriminate in their views between different types of medication or different aspects of their use. This suggests that their attitudes are generated by quite fundamental values. Addressing these values may be important in encouraging GPs to adhere more closely to national and international guidelines

Cost-effectiveness of nicotine patches for smoking cessation in pregnancy: a placebo randomised controlled trial (SNAP)

Introduction: Smoking during pregnancy is the most important, preventable cause of adverse pregnancy outcomes including miscarriage, premature birth and low birth weight, with huge financial costs to the NHS. However, there are very few published economic evaluations of smoking cessation interventions in pregnancy and previous studies are predominantly US-based and do not present incremental cost-effectiveness ratios (ICER). A number of studies have demonstrated cost-effectiveness of nicotine replacement therapy (NRT) in the general population, but this has yet to be tested among pregnant smokers. Methods: A cost-effectiveness analysis was undertaken alongside the SNAP trial to compare NRT patches plus behavioural support to behavioural support alone, for pregnant women who smoked. Results: At delivery, biochemically verified quit rates were slightly higher at 9.4% in the NRT group compared to 7.6% in the control group (odds ratio: 1.26, 95% CI: 0.82-1.96), at an increased cost of around £90 per participant. Higher costs in the NRT group were mainly attributable to the cost of NRT patches (mean = £46.07). The incremental cost-effectiveness ratio associated with NRT was £4,926 per quitter and a sensitivity analysis including only singleton births yielded an ICER of £4,156 per quitter. However, wide confidence intervals indicated a high level of uncertainty. Conclusions: Without a specific willingness to pay threshold, and due to high levels of statistical uncertainty, it is hard to determine the cost-effectiveness of NRT in this population. Furthermore, future research should address compliance issues, as these may dilute any potential effects of NRT, thus reducing the cost-effectiveness

The Hubble Constant from Observations of the Brightest Red Giant Stars in a Virgo-Cluster Galaxy

The Virgo and Fornax clusters of galaxies play central roles in determining the Hubble constant H_0. A powerful and direct way of establishing distances for elliptical galaxies is to use the luminosities of the brightest red-giant stars (the TRGB luminosity, at M_I = -4.2). Here we report the direct observation of the TRGB stars in a dwarf elliptical galaxy in the Virgo cluster. We find its distance to be 15.7 +- 1.5 Megaparsecs, from which we estimate a Hubble constant of H_0 = 77 +- 8 km/s/Mpc. Under the assumption of a low-density Universe with the simplest cosmology, the age of the Universe is no more than 12-13 billion years.Comment: 12 pages, LaTeX, with 2 postscript figures; in press for Nature, July 199

Potential effects of oilseed rape expressing oryzacystatin-1 (OC-1) and of purified insecticidal proteins on larvae of the solitary bee Osmia bicornis

Despite their importance as pollinators in crops and wild plants, solitary bees have not previously been included in non-target testing of insect-resistant transgenic crop plants. Larvae of many solitary bees feed almost exclusively on pollen and thus could be highly exposed to transgene products expressed in the pollen. The potential effects of pollen from oilseed rape expressing the cysteine protease inhibitor oryzacystatin-1 (OC-1) were investigated on larvae of the solitary bee Osmia bicornis (= O. rufa). Furthermore, recombinant OC-1 (rOC-1), the Bt toxin Cry1Ab and the snowdrop lectin Galanthus nivalis agglutinin (GNA) were evaluated for effects on the life history parameters of this important pollinator. Pollen provisions from transgenic OC-1 oilseed rape did not affect overall development. Similarly, high doses of rOC-1 and Cry1Ab as well as a low dose of GNA failed to cause any significant effects. However, a high dose of GNA (0.1%) in the larval diet resulted in significantly increased development time and reduced efficiency in conversion of pollen food into larval body weight. Our results suggest that OC-1 and Cry1Ab expressing transgenic crops would pose a negligible risk for O. bicornis larvae, whereas GNA expressing plants could cause detrimental effects, but only if bees were exposed to high levels of the protein. The described bioassay with bee brood is not only suitable for early tier non-target tests of transgenic plants, but also has broader applicability to other crop protection products

Public administration in an age of austerity:the future of the discipline

Reflecting changes in the nature of governance, some have questioned whether Public Administration is now an historical anachronism. While a legitimate debate exists between sceptics and optimists, this special issue demonstrates grounds for optimism by indicating the continuing diversity and adaptability of the field of Public Administration. In this introduction, we first sketch the variety of intellectual traditions which comprise the field of modern Public Administration. We then consider institutional challenges facing the subject given considerable pressures towards disciplinary fragmentation, and ideological challenges arising from a new distrust of public provision in the UK. Despite these challenges, Public Administration continues to provide a framework to analyse the practice of government and governance, governing institutions and traditions, and their wider sociological context. It can also directly inform policy reform - even if this endeavour can have its own pitfalls and pratfalls for the 'engaged' academic. We further suggest that, rather than lacking theoretical rigour, new approaches are developing that recognise the structural and political nature of the determinants of public administration. Finally, we highlight the richness of modern comparative work in Public Administration. Researchers can usefully look beyond the Atlantic relationship for theoretical enhancement and also consider more seriously the recursive and complex nature of international pressures on public administration