3,477 research outputs found
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The effect of the alternative prey, Paramecium caudatum (Peniculida: Parameciidae), on the predation of Culex pipiens (Diptera: Culicidae) by the copepods Macrocyclops albidus and Megacyclops viridis (Cyclopoida: Cyclopidae)
Biological control can be an effective tool to combat public health risks associated with mosquito-borne disease. However, target impacts of biological control agents may be reduced by biotic contexts such as the presence of alternative prey. In turn, this can impede our ability to realistically assess biocontrol agent efficacy. Here, we examine the effects of alternative ciliate prey on the predation potential of two cyclopoid copepods, Macrocyclops albidus Jurine (Cyclopoida: Cyclopidae) and Megacyclops viridis Jurine (Cyclopoida: Cyclopidae), towards larvae of the West Nile virus vector mosquito Culex pipiens Linnaeus (Diptera: Culicidae). Using functional responses (FRs; resource use under different resource densities), we demonstrate that both copepods exhibit potentially destabilising Type II FRs towards mosquito prey. However, where the alternative prey was present, we observed species-specific modulations to FR form and magnitude. For M. albidus, FRs remained Type II where ciliate prey were present, however, maximum feeding rates on mosquito larvae were reduced. Conversely, for M. viridis, FRs moved towards more stabilising Type III, whilst maximum feeding rates on mosquito larvae were not significantly reduced. Whilst both species of cyclopoid copepod were able to effectively target and consume larval mosquitoes in the presence of alternative prey, we demonstrate that overall efficacies may be reduced in aquatic habitats which contain multiple prey types. We thus advocate that biotic contexts such as prey selectivity should be integrated into predatory biocontrol agent examinations for mosquitoes which vector pathogens and parasites, to more holistically assess their efficacy
Are conservation actions reducing the threat to India's vulture populations?
Research Communications.-- et al.Veterinary use of the non-steroidal anti-inflammatory drug, diclofenac is responsible for the population collapse of resident vulture species in India. Conservation efforts, including a ban on veterinary diclofenac and the identification of a vulture-safe alternative (meloxicam), were introduced in 2006 in order to address the threat. Sampling of domesticated ungulate carcasses available to vultures in India was undertaken in three surveys prior to, around the time of, and 1-2 years after the ban in order to quantify the prevalence of diclofenac and meloxicam residues. A total of 1445, 1488 and 1251 liver tissue samples were collected from nine states and analysed with a validated LC-ESI/MS methodology. Overall diclofenac prevalence levels declined by almost a half over the three surveys, and there was an increase in meloxicam prevalence between the second and third surveys, although some states revealed little change. These surveys indicate that two of the key conservation actions to counter the threat faced by vultures - banning veterinary diclofenac and promoting meloxicam as a safe alternative - are beginning to take effect. However, because only a small proportion of diclofenac-contaminated carcasses is sufficient to cause vulture population declines, further efforts are needed to eliminate diclofenac from the food supply of India's vultures.The research was funded by the UK Government’s Darwin Initiative programme and by the
Royal Society for the Protection of Birds, UK.Peer Reviewe
Strong "quantum" chaos in the global ballooning mode spectrum of three-dimensional plasmas
The spectrum of ideal magnetohydrodynamic (MHD) pressure-driven (ballooning)
modes in strongly nonaxisymmetric toroidal systems is difficult to analyze
numerically owing to the singular nature of ideal MHD caused by lack of an
inherent scale length. In this paper, ideal MHD is regularized by using a
-space cutoff, making the ray tracing for the WKB ballooning formalism a
chaotic Hamiltonian billiard problem. The minimum width of the toroidal Fourier
spectrum needed for resolving toroidally localized ballooning modes with a
global eigenvalue code is estimated from the Weyl formula. This
phase-space-volume estimation method is applied to two stellarator cases.Comment: 4 pages typeset, including 2 figures. Paper accepted for publication
in Phys. Rev. Letter
Biological control agent selection under environmental change using functional responses, abundances and fecundities; the Relative Control Potential (RCP) metric
We currently lack the capacity to rapidly and reliably predict the efficacy of biological control agents due to inadequate consistency in derivations of functional and numerical responses and potential effects of context-dependencies. Here, we propose and apply a novel metric, Relative Control Potential (RCP), which combines the functional response (FR, per capita effect) with proxies for the numerical response (NR, agent population response) to compare agent efficacies, where RCP = FR × abundance (or other proxies e.g. fecundity). The RCP metric is a comparative ratio between potential biocontrol agents, where values > 1 indicate higher relative control efficacy. Further, RCP can compare the efficacy of agents under environmental contexts, such as temperature change. We thus derived the RCP for two predatory cyclopoid copepods, Macrocyclops albidus (Cyclopoida: Cyclopidae) and Megacyclops viridis (Cyclopoida: Cyclopidae), towards larvae of the mosquito Culex pipiens (Diptera: Culicidae) under temperatures representative of current and future climate. Both copepods exhibited potentially population destabilising Type II FRs, with increasing temperatures inducing greater magnitude FRs through increased attack rates and decreased handling times. Attack rates by M. albidus were higher than M. viridis, yet handling times and maximum feeding rates were similar between the species across all temperatures. The inclusion of abundance data drives an elevated RCP of M. albidus and the integration of fecundity drives greater RCP of M. albidus at peak temperatures. Q10 values are indicative of increased feeding activity by both copepods with temperature increases, however relative feeding level increases of M. viridis slowed towards the peak temperature. We present RCP calculations and biplots that represent the comparative efficacies of the two biological control agents across temperatures. The Relative Control Potential (RCP) metric thus provides a new tool for practitioners to better assess the potential efficacy of biocontrol agents before their integration into management approaches for pests, vectors and invasive species
Stabilizing Constructs through Collaboration across Different Research Fields as a Way to Foster the Integrative Approach of the Research Domain Criteria (RDoC) Project
In this article, I explain why stabilizing constructs is important to the success of the Research Domain Criteria Project and identify one measure for facilitating such stability
Extraction and Separation Modeling of Orion Test Vehicles with ADAMS Simulation
The Capsule Parachute Assembly System (CPAS) project has increased efforts to demonstrate the performance of fully integrated parachute systems at both higher dynamic pressures and in the presence of wake fields using a Parachute Compartment Drop Test Vehicle (PCDTV) and a Parachute Test Vehicle (PTV), respectively. Modeling the extraction and separation events has proven challenging and an understanding of the physics is required to reduce the risk of separation malfunctions. The need for extraction and separation modeling is critical to a successful CPAS test campaign. Current PTV-alone simulations, such as Decelerator System Simulation (DSS), require accurate initial conditions (ICs) drawn from a separation model. Automatic Dynamic Analysis of Mechanical Systems (ADAMS), a Commercial off the Shelf (COTS) tool, was employed to provide insight into the multi-body six degree of freedom (DOF) interaction between parachute test hardware and external and internal forces. Components of the model include a composite extraction parachute, primary vehicle (PTV or PCDTV), platform cradle, a release mechanism, aircraft ramp, and a programmer parachute with attach points. Independent aerodynamic forces were applied to the mated test vehicle/platform cradle and the separated test vehicle and platform cradle. The aero coefficients were determined from real time lookup tables which were functions of both angle of attack ( ) and sideslip ( ). The atmospheric properties were also determined from a real time lookup table characteristic of the Yuma Proving Grounds (YPG) atmosphere relative to the planned test month. Representative geometries were constructed in ADAMS with measured mass properties generated for each independent vehicle. Derived smart separation parameters were included in ADAMS as sensors with defined pitch and pitch rate criteria used to refine inputs to analogous avionics systems for optimal separation conditions. Key design variables were dispersed in a Monte Carlo analysis to provide the maximum expected range of the state variables at programmer deployment to be used as ICs in DSS. Extensive comparisons were made with Decelerator System Simulation Application (DSSA) to validate the mated portion of the ADAMS extraction trajectory. Results of the comparisons improved the fidelity of ADAMS with a ramp pitch profile update from DSSA. Post-test reconstructions resulted in improvements to extraction parachute drag area knock-down factors, extraction line modeling, and the inclusion of ball-to-socket attachments used as a release mechanism on the PTV. Modeling of two Extraction parachutes was based on United States Air Force (USAF) tow test data and integrated into ADAMS for nominal and Monte Carlo trajectory assessments. Video overlay of ADAMS animations and actual C-12 chase plane test videos supported analysis and observation efforts of extraction and separation events. The COTS ADAMS simulation has been integrated with NASA based simulations to provide complete end to end trajectories with a focus on the extraction, separation, and programmer deployment sequence. The flexibility of modifying ADAMS inputs has proven useful for sensitivity studies and extraction/separation modeling efforts.
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Continuing mortality of vultures in India associated with illegal veterinary use of diclofenac and a potential threat from nimesulide
AbstractThe collapse of South Asia's Gyps vulture populations is attributable to the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Vultures died after feeding on carcasses of recently-medicated animals. The governments of India, Nepal and Pakistan banned the veterinary use of diclofenac in 2006. We analysed results of 62 necropsies and 48 NSAID assays of liver and/or kidney for vultures of five species found dead in India between 2000 and 2012. Visceral gout and diclofenac were detected in vultures from nine states and three species: Gyps bengalensis, Gyps indicus and Gyps himalayensis. Visceral gout was found in every vulture carcass in which a measurable level of diclofenac was detected. Meloxicam, an NSAID of low toxicity to vultures, was found in two vultures and nimesulide in five vultures. Nimesulide at elevated tissue concentrations was associated with visceral gout in four of these cases, always without diclofenac, suggesting that nimesulide may have similar toxic effects to those of diclofenac. Residues of meloxicam on its own were never associated with visceral gout. The proportion of Gyps vultures found dead in the wild in India with measurable levels of diclofenac in their tissues showed a modest and non-significant decline since the ban on the veterinary use of diclofenac. The prevalence of visceral gout declined less, probably because some cases of visceral gout from 2008 onwards were associated with nimesulide rather than diclofenac. Veterinary use of nimesulide is a potential threat to the recovery of vulture populations.Financial support and assistance for the project from the Director, Indian Veterinary Research Institute (IVRI), the UK Government’s Darwin Initiative and the Royal Society for the Protection of Birds is gratefully acknowledged.This is the accepted manuscript. The final version is available from Cambridge University Press via http://dx.doi.org/10.1017/S003060531500037
Rodent eradication scaled up:clearing rats and mice from South Georgia
The Subantarctic island of South Georgia lost most of its birds to predation by rodents introduced by people over 2 centuries. In 2011 a UK charity began to clear brown rats Rattus norvegicus and house mice Mus musculus from the 170 km long, 3,500 km2 island using helicopters to spread bait containing Brodifacoum as the active ingredient. South Georgia's larger glaciers were barriers to rodent movement, resulting in numerous independent sub-island populations. The eradication could therefore be spread over multiple seasons, giving time to evaluate results before recommencing, and also reducing the impact of non-target mortality across the island as a whole. Eradication success was achieved in the 128 km2 Phase 1 trial operation. Work in 2013 (Phase 2) and early 2015 (Phase 3) covered the remaining 940 km2 occupied by rodents. By July 2017, 28 months after baiting was concluded, there was no sign of surviving rodents, other than one apparently newly introduced by ship in October 2014. A survey using detection dogs and passive devices will search the Phase 2 and Phase 3 land for rodents in early 2018. Seven (of 30) species of breeding birds suffered losses from poisoning, but all populations appear to have recovered within 5 years. The endemic South Georgia pipit Anthus antarcticus was the first bird to breed in newly rat-free areas, but there were also signs that cavity-nesting seabirds were exploring scree habitat denied them for generations. Enhanced biosecurity measures on South Georgia are needed urgently to prevent rodents being reintroduced.</p
Intra-amniotic delivery of CFTR-expressing adenovirus does not reverse cystic fibrosis phenotype in inbred CFTR-knockout mice
This article is available open access through the publisher’s website at the link below. Copyright © 2008 The American Society of Gene Therapy.Due to its early onset and severe prognosis, cystic fibrosis (CF) has been suggested as a candidate disease for in utero gene therapy. In 1997, a study was published claiming that to how transient prenatal expression of CF transmembrane conductance regulator (CFTR) from an in utero –injected adenovirus vector could achieve permanent reversal of the CF intestinal pathology in adult CF knockout mice, despite the loss of CFTR transgene expression by birth. This would imply that the underlying cause of CF is a prenatal defect for which lifelong cure can be achieved by transient prenatal expression of CFTR. Despite criticism at the time of publication, no independent verification of this contentious finding has been published so far. This is vital for the development of future therapeutic strategies as it may determine whether CF gene therapy should be performed prenatally or postnatally. We therefore reinvestigated this finding with an identical adenoviral vector and a knockout CF mouse line (CftrtmlCam) with a completely inbred genetic background to eliminate any effects due to genetic variation. After delivery of the CFTR-expressing adenovirus to the fetal mouse, both vector DNA and transgenic CFTR expression were detected in treated animals postpartum but statistically no significant difference in survival was observed between the Cftr–/– mice treated with the CFTR-adenovirus and those treated with the control vector.Sport Aiding Medical Research for Kids, the
Cystic Fibrosis Trust, and the Katharine Dormandy Trust
Asexuality: Classification and characterization
This is a post-print version of the article. The official published version can be obtaineed at the link below.The term “asexual” has been defined in many different ways and asexuality has received very little research attention. In a small qualitative study (N = 4), individuals who self-identified as asexual were interviewed to help formulate hypotheses for a larger study. The second larger study was an online survey drawn from a convenience sample designed to better characterize asexuality and to test predictors of asexual identity. A convenience sample of 1,146 individuals (N = 41 self-identified asexual) completed online questionnaires assessing sexual history, sexual inhibition and excitation, sexual desire, and an open-response questionnaire concerning asexual identity. Asexuals reported significantly less desire for sex with a partner, lower sexual arousability, and lower sexual excitation but did not differ consistently from non-asexuals in their sexual inhibition scores or their desire to masturbate. Content analyses supported the idea that low sexual desire is the primary feature predicting asexual identity
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