2,786 research outputs found
Species of Bursaphelenchus Fuchs, 1937 (Nematoda: Parasitaphelenchidae) and other nematode genera associated with insects from Pinus pinaster in Portugal
Insects associated with maritime pine, Pinus pinaster, in Portugal were collected
and screened for the presence of Bursaphelenchus species. Nematodes were
identified using Internal Transcribed Spacers-Restriction Fragment Length
Polymorphism (ITS-RFLP) analysis of dauer juveniles and morphological
identification of adults that developed from dauer juveniles on fungal cultures
or on cultures in pine wood segments at 26 C. Several associations are
described: Bursaphelenchus teratospicularis and Bursaphelenchus sexdentati are
associated with Orthotomicus erosus; Bursaphelenchus tusciae, B. sexdentati and/or
Bursaphelenchus pinophilus with Hylurgus ligniperda and Bursaphelenchus hellenicus
with Tomicus piniperda, Ips sexdentatus and H. ligniperda. An unidentified
Bursaphelenchus species is vectored by Hylobius sp. The previously reported
association of Bursaphelenchus xylophilus with Monochamus galloprovincialis
was confirmed. The association of Bursaphelenchus leoni with Pityogenes sp. is
not definitively established and needs further studies for clarification.
Other nematode genera besides Bursaphelenchus were found to be associated
with the insects sampled, including two different species of Ektaphelenchus, Parasitorhabditis
sp., Parasitaphelenchus sp., Contortylenchus sp. and other unidentified
nematodes. The Ektaphelenchus species found in O. erosus is morphologically
similar to B. teratospicularis found in the same insect; adults of both the species
are found in cocoon-like structures under the elytra of the insects.
Introduction
Approximately one third of the nematodes belonging to
the order Aphelenchida Siddiqi, 1980 are associated with
insects (Poinar, 1983). These nematodes establish a variety
of associations with the insects, which may be
described as commensalism, e.g. phoresy (to the benefit
of the nematode but not affecting the insect), mutualism
(both the organisms benefit) or parasitism (nematodes
benefit at the expense of the insect) (Giblin-Davis,
2004).
Most Bursaphelenchus Fuchs, 1937 species are mycetophagous,
feeding on fungi in the galleries of bark beetles
and thu
Assessing the effects of repeated handling on physiology and condition of semi-precocial nestlings
Repeated exposure to elevated levels of glucocorticoids during development can have long-term detrimental effects on survival and fitness, potentially associated with increased telomere attrition. Nestling birds are regularly handled for ecological research, yet few authors have considered the potential for handling-induced stress to influence hormonally-mediated phenotypic development or bias interpretations of subsequent focal measurements. We experimentally manipulated the handling experience of the semi-precocial nestlings of European Storm Petrel Hydrobates pelagicus to simulate handling in a typical field study and examined cumulative effects on physiology and condition in late postnatal development. Neither baseline corticosterone (the primary glucocorticoid in birds), telomere length nor body condition varied with the number of handling episodes. The absence of a response could be explained if Storm Petrels did not perceive handling to be stressful or if there is dissociation of the hypothalamic-pituitary-adrenal axis from stressful stimuli in early life. Eliciting a response to a stressor may be maladaptive for cavity-dwelling young that are unable to escape or defend themselves. Furthermore, avoiding elevated overall glucocorticoid exposure may be particularly important in a long-lived species, in which accelerated early-life telomere erosion could impact negatively upon longevity. We propose that the level of colony-wide disturbance induced by investigator handling of young could be important in underlining species-specific responses. Storm Petrel nestlings appear unresponsive to investigator handling within the limits of handling in a typical field study and handling at this level should not bias physiological and morphological measurements
NLSEmagic: Nonlinear Schr\"odinger Equation Multidimensional Matlab-based GPU-accelerated Integrators using Compact High-order Schemes
We present a simple to use, yet powerful code package called NLSEmagic to
numerically integrate the nonlinear Schr\"odinger equation in one, two, and
three dimensions. NLSEmagic is a high-order finite-difference code package
which utilizes graphic processing unit (GPU) parallel architectures. The codes
running on the GPU are many times faster than their serial counterparts, and
are much cheaper to run than on standard parallel clusters. The codes are
developed with usability and portability in mind, and therefore are written to
interface with MATLAB utilizing custom GPU-enabled C codes with the
MEX-compiler interface. The packages are freely distributed, including user
manuals and set-up files.Comment: 37 pages, 13 figure
Bogomol'nyi Bounds for Gravitational Cosmic Strings
We present a new method for finding lower bounds on the energy of topological
cosmic string solutions in gravitational field theories. This new method
produces bounds that are valid over the entire space of solutions, unlike the
traditional approach, where the bounds obtained are only valid for
cylindrically symmetric solutions. This method is shown to be a generalisation
of the well-known Bogomol'nyi procedure for non-gravitational theories and as
such, it can be used to find gravitational Bogomol'nyi bounds for models
wherever the traditional Bogomol'nyi procedure can be applied in the
non-gravitational limit. Furthermore, this method yields Bogomol'nyi equations
that do not rule out the existence of asymmetric bound-saturating solutions.Comment: 17 pages - final version (accepted for publication in JHEP
The most creative organization in the world? The BBC, 'creativity' and managerial style
The managerial styles of two BBC directors-general, John Birt and Greg Dyke, have often been contrasted but not so far analysed from the perspective of their different views of 'creative management'. This article first addresses the orthodox reading of 'Birtism'; second, it locates Dyke's 'creative' turn in the wider context of fashionable neo-management theory and UK government creative industries policy; third, it details Dyke's drive to change the BBC's culture; and finally, it concludes with some reflections on the uncertainties inherent in managing a creative organisation
Open-label, cluster randomised controlled trial and economic evaluation of a brief letter from a GP on unscheduled medical contacts associated with the start of the school year: the PLEASANT trial
BACKGROUND: Asthma is seasonal with peaks in exacerbation rates in school-age children associated with the return to school following the summer vacation. A drop in prescription collection in August is associated with an increase in the number of unscheduled contacts after the school return. OBJECTIVE: To assess whether a public health intervention delivered in general practice reduced unscheduled medical contacts in children with asthma. DESIGN: Cluster randomised trial with trial-based economic evaluation. Randomisation was at general practice level, stratified by size of practice. The intervention group received a letter from their general practitioner (GP) in late July outlining the importance of (re)taking asthma medication before the return to school. The control group was usual care. SETTING: General practices in England and Wales. PARTICIPANTS: 12 179 school-age children in 142 general practices (70 randomised to intervention). MAIN OUTCOME: Proportion of children aged 5-16 years who had an unscheduled contact in September. Secondary endpoints included collection of prescriptions in August and medical contacts over 12 months (September-August). Economic endpoints were quality-adjusted life-years gained and health service costs. RESULTS: There was no evidence of effect (OR 1.09; 95% CI 0.96 to 1.25 against treatment) on unscheduled contacts in September. The intervention increased the proportion of children collecting a prescription in August by 4% (OR 1.43; 95% CI 1.24 to 1.64). The intervention also reduced the total number of medical contacts between September-August by 5% (incidence ratio 0.95; 95% CI 0.91 to 0.99).The mean reduction in medical contacts informed the health economics analyses. The intervention was estimated to save £36.07 per patient, with a high probability (96.3%) of being cost-saving. CONCLUSIONS: The intervention succeeded in increasing children collecting prescriptions. It did not reduce unscheduled care in September (the primary outcome), but in the year following the intervention, it reduced the total number of medical contacts. TRIAL REGISTRATION NUMBER: ISRCTN03000938; Results
Momentum flux density, kinetic energy density and their fluctuations for one-dimensional confined gases of non-interacting fermions
We present a Green's function method for the evaluation of the particle
density profile and of the higher moments of the one-body density matrix in a
mesoscopic system of N Fermi particles moving independently in a linear
potential. The usefulness of the method is illustrated by applications to a
Fermi gas confined in a harmonic potential well, for which we evaluate the
momentum flux and kinetic energy densities as well as their quantal mean-square
fluctuations. We also study some properties of the kinetic energy functional
E_{kin}[n(x)] in the same system. Whereas a local approximation to the kinetic
energy density yields a multi-valued function, an exact single-valued
relationship between the density derivative of E_{kin}[n(x)] and the particle
density n(x) is demonstrated and evaluated for various values of the number of
particles in the system.Comment: 10 pages, 5 figure
Traditional and Health-Related Philanthropy: The Role of Resources and Personality
I study the relationships of resources and personality characteristics to charitable giving, postmortem organ donation, and blood donation in a nationwide sample of persons in households in the Netherlands. I find that specific personality characteristics are related to specific types of giving: agreeableness to blood donation, empathic concern to charitable giving, and prosocial value orientation to postmortem organ donation. I find that giving has a consistently stronger relation to human and social capital than to personality. Human capital increases giving; social capital increases giving only when it is approved by others. Effects of prosocial personality characteristics decline at higher levels of these characteristics. Effects of empathic concern, helpfulness, and social value orientations on generosity are mediated by verbal proficiency and church attendance.
Convenient Versus Unique Effective Action Formalism in 2D Dilaton-Maxwell Quantum Gravity
The structure of one-loop divergences of two-dimensional dilaton-Maxwell
quantum gravity is investigated in two formalisms: one using a convenient
effective action and the other a unique effective action. The one-loop
divergences (including surface divergences) of the convenient effective action
are calculated in three different covariant gauges: (i) De Witt, (ii)
-degenerate De Witt, and (iii) simplest covariant. The on-shell
effective action is given by surface divergences only (finiteness of the
-matrix), which yet depend upon the gauge condition choice.
Off-shell renormalizability is discussed and classes of renormalizable
dilaton and Maxwell potentials are found which coincide in the cases of
convenient and unique effective actions. A detailed comparison of both
situations, i.e. convenient vs. unique effective action, is given. As an
extension of the procedure, the one-loop effective action in two-dimensional
dilaton-Yang-Mills gravity is calculated.Comment: 25 pages, LaTeX file, HUPD-93-0
Low-Prandtl-number B\'enard-Marangoni convection in a vertical magnetic field
The effect of a homogeneous magnetic field on surface-tension-driven
B\'{e}nard convection is studied by means of direct numerical simulations. The
flow is computed in a rectangular domain with periodic horizontal boundary
conditions and the free-slip condition on the bottom wall using a
pseudospectral Fourier-Chebyshev discretization. Deformations of the free
surface are neglected. Two- and three-dimensional flows are computed for either
vanishing or small Prandtl number, which are typical of liquid metals. The main
focus of the paper is on a qualitative comparison of the flow states with the
non-magnetic case, and on the effects associated with the possible
near-cancellation of the nonlinear and pressure terms in the momentum equations
for two-dimensional rolls. In the three-dimensional case, the transition from a
stationary hexagonal pattern at the onset of convection to three-dimensional
time-dependent convection is explored by a series of simulations at zero
Prandtl number.Comment: 26 pages, 9 figure
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