906 research outputs found
Phylogeny of Geomydoecus and Thomomydoecus pocket gopher lice (phthiraptera, trichodectidae) inferred from cladistic analysis of adult and first instar morphology
The phylogeny for all 122 species and subspecies of chewing lice of the genera Geomydoecus and Thomomydoecus (Phthiraptera: Trichodectidae) hosted by pocket gophers (Rodentia: Geomyidae) is estimated by a cladistic analysis of fifty-eight morphological characters obtained from adults and first instars. The data set has considerable homoplasy, but still contains phylogenetic information. The phylogeny obtained is moderately resolved and, with some notable exceptions, supports the species complexes proposed by Hellenthal and Price over the the last two decades. The subgenera G. (Thaelerius) and T. (Thomomydoecus) are both shown to be monophyletic, but the monophly of subgenus T. (Jamespattonius) could not be confirmed, perhaps due to the lack of first-instar data for one of its component species. The nominate subgenus of Geomydoecus may be monophyletic, but our cladogram was insufficiently resolved to corroborate this. Mapping the pocket gopher hosts onto the phylogeny reveals a consistent pattern of louse clades being restricted to particular genera or subgenera of gophers, but the history of the host-parasite association appears complex and will require considerable effort to resolve
Micromagnetic modelling and imaging of vortex/merons structures in an oxide | metal heterostructure
Using micromagnetic simulations, we have modelled the formation of imprinted merons and anti-merons in cobalt overlayers of different thickness (1-8 nm), stabilised by interfacial exchange with antiferromagnetic vortices in α-Fe2O3. Structures similar to those observed experimentally could be obtained with reasonable exchange parameters, also in the presence of surface roughness. We produce simulated meron/antimeron images by magnetic force microscopy (MFM) and nitrogen-vacancy (N-V) centre microscopy, and established signatures of these topological structures in different experimental configurations
The Prevalence and Intensity of Louse (Pthiraptera, Mallophaga) and Tick (Acarina,Ixodidae) Infestation of Birds in South African Grassland
A total of 270 birds represented by 12 species were examined for the presence of lice and ticks. Birds were collected in South African grasslands. Extensity of louse and tick infestation ranged from 10% to 80% and from 3% to 33% respectively. Average number of lice per host species ranged from 1 to 15, while average number of ticks per host species ranged from 1 to 5. Only single specimens (0.4%) were heavily parasited by lice and ticks respectively. Lice infested birds more often during the dry season, while ticks infested birds mainly during the rain season.В общей сложности 270 птиц 12 видов были обследованы на наличие пухоедов и клещей. Птицы были собраны на южноафриканских пастбищах. Экстенсивность зараженности пухоедами и клещами колеблется от 10% до 80% и от 3% до 33%, соответственно. Среднее количество пухоедов на вид-прокормитель колеблется от 1 до 15, а среднее число клещей на вид-прокормитель – от 1 до 5. Только единичные особи (0,4%) были сильно паразитированы пухоедами и клещами соответственно. Пухоеды заражали птиц чаще всего во время сухого сезона, в то время как клещи заражали птиц в основном во время сезона дождей
On testing global optimization algorithms for space trajectory design
In this paper we discuss the procedures to test a global search algorithm applied to a space trajectory design problem. Then, we present some performance indexes that can
be used to evaluate the effectiveness of global optimization algorithms. The performance
indexes are then compared highlighting the actual significance of each one of them. A number of global optimization algorithms are tested on four typical space trajectory design problems. From the results of the proposed testing procedure we infer for each pair
algorithm-problem the relation between the heuristics implemented in the solution algorithm and the main characteristics of the problem under investigation. From this analysis we derive a novel interpretation of some evolutionary heuristics, based on dynamical system
theory and we significantly improve the performance of one of the tested algorithms
Lice on helmeted guineafowls at five localities in South Africa
A total of 234 helmeted guineafowls, Numida meleagris coronata , were examined for lice at five localities
in South Africa. These were the Mountain Zebra National Park in the eastern Karoo, Cape Province; the
Andries Vosloo Kudu Reserve and the farm Bucklands, in Valley Bushveld, eastern Cape Province; the
Bontebok National Park, south-western Cape Province; and the southern part of the Kruger National Park,
eastern Transvaal Lowveld.
A total of eight louse species, comprising Amyrsidea desousai, Clayia theresae, Goniodes gigas, Goniodes
numidae, Lipeurus numidae, Numidicola antennatus, Numidilipeurus lawrensis and Somaphantus lusius
were recovered from the guineafowls. With the exception of A. desousai, which was not recovered from
the guineafowls in the Bontebok National Park, all eight species were present on the birds at each locality.
The prevalence of infestations on the birds at the various localities ranged from 99,2-100%, and the numbers
of lice present on individual birds, from 0-3619. Goniodes spp. and N. antennatus were the most abundant
and A. desousai the least.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Foundation for Research Development. National Parks Board. South African Nature Foundation. Bayer Animal Health.mn201
Genetic determinants of cellular addiction to DNA polymerase theta
Polymerase theta (Pol θ, gene name Polq) is a widely conserved DNA polymerase that mediates a microhomology-mediated, error-prone, double strand break (DSB) repair pathway, referred to as Theta Mediated End Joining (TMEJ). Cells with homologous recombination deficiency are reliant on TMEJ for DSB repair. It is unknown whether deficiencies in other components of the DNA damage response (DDR) also result in Pol θ addiction. Here we use a CRISPR genetic screen to uncover 140 Polq synthetic lethal (PolqSL) genes, the majority of which were previously unknown. Functional analyses indicate that Pol θ/TMEJ addiction is associated with increased levels of replication-associated DSBs, regardless of the initial source of damage. We further demonstrate that approximately 30% of TCGA breast cancers have genetic alterations in PolqSL genes and exhibit genomic scars of Pol θ/TMEJ hyperactivity, thereby substantially expanding the subset of human cancers for which Pol θ inhibition represents a promising therapeutic strategy
Cold Plasma Wave Analysis in Magneto-Rotational Fluids
This paper is devoted to investigate the cold plasma wave properties. The
analysis has been restricted to the neighborhood of the pair production region
of the Kerr magnetosphere. The Fourier analyzed general relativistic
magnetohydrodynamical equations are dealt under special circumstances and
dispersion relations are obtained. We find the -component of the complex
wave vector numerically. The corresponding components of the propagation
vector, attenuation vector, phase and group velocities are shown in graphs. The
direction and dispersion of waves are investigated.Comment: 22 pages, 18 figures, accepted for publication in Astrophys. Space
Sc
Characterization of neutrino signals with radiopulses in dense media through the LPM effect
We discuss the possibilities of detecting radio pulses from high energy
showers in ice, such as those produced by PeV and EeV neutrino interactions. It
is shown that the rich radiation pattern structure in the 100 MHz to few GHz
allows the separation of electromagnetic showers induced by photons or
electrons above 100 PeV from those induced by hadrons. This opens up the
possibility of measuring the energy fraction transmitted to the electron in a
charged current electron neutrino interaction with adequate sampling of the
angular distribution of the signal. The radio technique has the potential to
complement conventional high energy neutrino detectors with flavor information.Comment: 5 pages, 4 ps figures. Submitted to Phys. Rev. Let
Ten Proofs of the Generalized Second Law
Ten attempts to prove the Generalized Second Law of Thermodyanmics (GSL) are
described and critiqued. Each proof provides valuable insights which should be
useful for constructing future, more complete proofs. Rather than merely
summarizing previous research, this review offers new perspectives, and
strategies for overcoming limitations of the existing proofs. A long
introductory section addresses some choices that must be made in any
formulation the GSL: Should one use the Gibbs or the Boltzmann entropy? Should
one use the global or the apparent horizon? Is it necessary to assume any
entropy bounds? If the area has quantum fluctuations, should the GSL apply to
the average area? The definition and implications of the classical,
hydrodynamic, semiclassical and full quantum gravity regimes are also
discussed. A lack of agreement regarding how to define the "quasi-stationary"
regime is addressed by distinguishing it from the "quasi-steady" regime.Comment: 60 pages, 2 figures, 1 table. v2: corrected typos and added a
footnote to match the published versio
Fluctuation Theorems for Entropy Production and Heat Dissipation in Periodically Driven Markov Chains
Asymptotic fluctuation theorems are statements of a Gallavotti-Cohen symmetry
in the rate function of either the time-averaged entropy production or heat
dissipation of a process. Such theorems have been proved for various general
classes of continuous-time deterministic and stochastic processes, but always
under the assumption that the forces driving the system are time independent,
and often relying on the existence of a limiting ergodic distribution. In this
paper we extend the asymptotic fluctuation theorem for the first time to
inhomogeneous continuous-time processes without a stationary distribution,
considering specifically a finite state Markov chain driven by periodic
transition rates. We find that for both entropy production and heat
dissipation, the usual Gallavotti-Cohen symmetry of the rate function is
generalized to an analogous relation between the rate functions of the original
process and its corresponding backward process, in which the trajectory and the
driving protocol have been time-reversed. The effect is that spontaneous
positive fluctuations in the long time average of each quantity in the forward
process are exponentially more likely than spontaneous negative fluctuations in
the backward process, and vice-versa, revealing that the distributions of
fluctuations in universes in which time moves forward and backward are related.
As an additional result, the asymptotic time-averaged entropy production is
obtained as the integral of a periodic entropy production rate that generalizes
the constant rate pertaining to homogeneous dynamics
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