1,242 research outputs found
Search for Antineutrino Charged Current Coherent Pion Production at SciBooNE
The SciBooNE experiment (Fermilab) recently published results of a search for
charged current coherent pion production in neutrino mode: muon neutrinos
scattering on carbon. The results of this study are that no evidence for
coherent pion production is observed, and SciBooNE set 90% confidence level
upper limits on the cross section ratio of charged current coherent pion
production to the total charged current cross section. Recently proposed new
coherent pion models predict a production of charged current coherent pion
events just below the SciBooNE's upper limit. Motivated by this, we performed a
search for charged current coherent pion production using SciBooNE's collected
antineutrino data since antineutrino data are expected to be more sensitive to
look at coherent pion production than neutrino data. This paper describes
preliminary results of a search for antineutrino charged current coherent pion
production at the SciBooNE experiment.Comment: 6 pages to be appeared in the proceedings for NuInt09 proceeding
The extended Malkus-Robbins dynamo as a perturbed Lorenz system
Recent investigations of some self-exciting Faraday-disk homopolar dynamo ([1-4]) have yielded the classic Lorenz equations as a special limit when one of the principal bifurcation parameters is zero. In this paper we focus upon one of those models [3] and illustrate what happens to some of the lowest order unstable periodic orbits as this parameter is increased from zero
Witnessing Macroscopic Entanglement in a Staggered Magnetic Field
We investigate macroscopic entanglement in an infinite XX spin-1/2 chain with
staggered magnetic field, B_l=B+e^{-i\pi l}b. Using single-site entropy and by
constructing an entanglement witness, we search for the existence of
entanglement when the system is at absolute zero, as well as in thermal
equilibrium. Although the role of the alternating magnetic field b is, in
general, to suppress entanglement as do B and T, we find that when T=0,
introducing b allows the existence of entanglement even when the uniform
magnetic field B is arbitrarily large. We find that the region and the amount
of entanglement in the spin chain can be enhanced by a staggered magnetic
field.Comment: Accepted for publication in Physical Review A, minor changes from
previous version. 5 pages, 3 figure
The Malkus–Robbins dynamo with a linear series motor
Hide [1997] has introduced a number of different nonlinear models to describe the behavior of n-coupled self-exciting Faraday disk homopolar dynamos. The hierarchy of dynamos based upon the Hide et al. [1996] study has already received much attention in the literature (see [Moroz, 2001] for a review). In this paper we focus upon the remaining dynamo, namely Case 3 of [Hide, 1997] for the particular limit in which the Malkus–Robbins dynamo [Malkus, 1972; Robbins, 1997] obtains, but now modified by the presence of a linear series motor. We compare and contrast the linear and the nonlinear behaviors of the two types of dynamo
Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats
The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite
felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction
between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study
investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat
density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%–47·79%) was observed despite this.
A comparable level of prevalence was observed in a previously published study using the same approaches where a
prevalence of 59% (95% CI: 50·13%–67·87%) was observed in a natural population of Mus domesticus from an area with high
cat density (>500 cats/km2). Detection of infected foetuses frompregnant dams in both populations suggests that congenital
transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora
caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%–6·66%); M. domesticus: 3·08%
(95% CI: 0·11%–6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in
these ecosystems
Broadband energy harvesting by nonlinear magnetic rolling pendulum with subharmonic resonance
This is the final version. Available on open access from Elsevier via the DOI in this recordNonlinear systems may exhibit secondary resonances, which can provide an additional and thus broadened bandwidth
for energy harvesting. However, the secondary resonances of nonlinear energy harvesters reported in the literature
suffer from low-power output and limited bandwidth. This work proposes a novel magnetic rolling pendulum (MRP)
with a large bandwidth and high power output in both primary and secondary resonances for energy harvesting. The
MRP employs the rolling motion of a magnetically levitated permanent magnet with minimal mechanical damping. A
prototype was fabricated and characterised. An analytical model combined with finite element analysis was developed
and validated by experiment. Both experiment and simulation show that the MRP has a linear resonance frequency of
4.6 Hz and peak power of 3.7 mW. It exhibits strong nonlinear behaviours and broadband characteristics with excitation
amplitude as low as 2 m/s2
in the primary resonance. As the excitation amplitude is larger than 5 m/s2
, the secondary
resonance (1/2 order subharmonics) is excited. The responses of the MRP at the subharmonic resonance takes the same
form as the primary resonance in terms of displacement and power outputs. This helps the subharmonic resonance to
produce the same power level as the primary resonance but with a larger bandwidth. When excited at 14 m/s2
, the MRP
shows 1-mW-bandwidth of 9.7 Hz, 2/3 of which is attributed to the subharmonic resonance.Engineering and Physical Sciences Research Council (EPSRC
Evidence for high levels of vertical transmission in Toxoplasma gondii
Toxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought
Human African trypanosomiasis : the current situation in endemic regions and the risks for non-endemic regions from imported cases
Human African trypanosomiasis (HAT) is caused by Trypanosoma brucei
gambiense and T. b. rhodesiense and caused devastating epidemics during the 20th
century. Due to effective control programs implemented in the last two decades, the
number of reported cases has fallen to a historically low level. Although fewer than
977 cases were reported in 2018 in endemic countries, HAT is still a public health
problem in endemic regions until it is completely eliminated. In addition, almost 150
confirmed HAT cases were reported in non-endemic countries in the last three
decades. The majority of non-endemic HAT cases were reported in Europe, United
States and South Africa, due to historical alliances, economic links or geographic
proximity to disease endemic countries. Furthermore, with the implementation of the
“Belt and Road” project, sporadic imported HAT cases have been reported in China
as a warning sign of tropical diseases prevention. In this paper, we explore and
interpret the data on HAT incidence and find no positive correlation between the
number of HAT cases from endemic and non-endemic countries.This data will
provide useful information for better understanding the imported cases of HAT
globally in the post-elimination phase
A rapid and simple method of detection of Blepharisma japonicum using PCR and immobilisation on FTA paper
BACKGROUND: The rapid expansion in the availability of genome and DNA sequence information has opened up new possibilities for the development of methods for detecting free-living protozoa in environmental samples. The protozoan Blepharisma japonicum was used to investigate a rapid and simple detection system based on polymerase chain reaction amplification (PCR) from organisms immobilised on FTA paper. RESULTS: Using primers designed from the α-tubulin genes of Blepharisma, specific and sensitive detection to the equivalent of a single Blepharisma cell could be achieved. Similar detection levels were found using water samples, containing Blepharisma, which were dried onto Whatman FTA paper. CONCLUSION: This system has potential as a sensitive convenient detection system for Blepharisma and could be applied to other protozoan organisms
Concurrence in Disordered Systems
Quantum systems exist at finite temperatures and are likely to be disordered
to some level. Since applications of quantum information often rely on
entanglement, we require methods which allow entanglement measures to be
calculated in the presence of disorder at non-zero temperatures. We demonstrate
how the disorder averaged concurrence can be calculated using thermal many-body
perturbation theory. Our technique can also be applied to other entanglement
measures. To illustrate, we find the disorder averaged concurrence of an XX
spin chain. We find that concurrence can be increased by disorder in some
parameter regimes.Comment: 14 pages, 5 figure
- …