153 research outputs found
Letter of Intent: Muonium R&D/Physics Program at the MTA
With the planned turn-on of the PIP-II 800 MeV superconducting proton linac,
Fermilab will potentially become the world's best laboratory at which to carry
out fundamental muon measurements, sensitive searches for symmetry violation,
and precision tests of theory. In preparation, we propose to develop the
techniques that will be needed. An R&D and physics program is proposed at the
Fermilab MeV Test Area to use the existing 400 MeV Linac to demonstrate the
efficient production of a slow muonium beam using stopped in a
~100-m-thick layer of superfluid helium, and to use that beam to measure
muonium gravity.Comment: 3 pages, submitted to Fermila
Synthesizing skyrmion bound pairs in Fe-Gd thin films
We show that properly engineered amorphous Fe-Gd alloy thin films with perpendicular magnetic anisotropy exhibit bound pairs of like-polarity, opposite helicity skyrmions at room temperature. Magnetic mirror symmetry planes present in the stripe phase, instead of chiral exchange, determine the internal skyrmion structure and the net achirality of the skyrmion phase. Our study shows that stripe domain engineering in amorphous alloy thin films may enable the creation of skyrmion phases with technologically desirable properties
Comparing genotyping algorithms for Illumina's Infinium whole-genome SNP BeadChips
Background: Illumina's Infinium SNP BeadChips are extensively used in both small and large-scale genetic studies. A fundamental step in any analysis is the processing of raw allele A and allele B intensities from each SNP into genotype calls (AA, AB, BB). Various algorithms which make use of different statistical models are available for this task. We compare four methods (GenCall, Illuminus, GenoSNP and CRLMM) on data where the true genotypes are known in advance and data from a recently published genome-wide association study.Results: In general, differences in accuracy are relatively small between the methods evaluated, although CRLMM and GenoSNP were found to consistently outperform GenCall. The performance of Illuminus is heavily dependent on sample size, with lower no call rates and improved accuracy as the number of samples available increases. For X chromosome SNPs, methods with sex-dependent models (Illuminus, CRLMM) perform better than methods which ignore gender information (GenCall, GenoSNP). We observe that CRLMM and GenoSNP are more accurate at calling SNPs with low minor allele frequency than GenCall or Illuminus. The sample quality metrics from each of the four methods were found to have a high level of agreement at flagging samples with unusual signal characteristics.Conclusions: CRLMM, GenoSNP and GenCall can be applied with confidence in studies of any size, as their performance was shown to be invariant to the number of samples available. Illuminus on the other hand requires a larger number of samples to achieve comparable levels of accuracy and its use in smaller studies (50 or fewer individuals) is not recommended
Reversal of patterned Co/Pd multilayers with graded magnetic anisotropy
Magnetization reversal and the effect of patterning have been investigated in full-film and dotarrays of Co/Pd multilayers, using the first-order reversal curve and scanning electron microscopywith polarization analysis techniques. The effect of patterning is most pronounced in lowsputtering pressure films, where the size of contiguous domains is larger than the dot size. Uponpatterning, each dot must have its own domain nucleation site and domain propagation is limitedwithin the dot. In graded anisotropy samples, the magnetically soft layer facilitates themagnetization reversal, once the reverse domains have nucleated
Experimental proposal for measuring the Gouy phase of matter waves
The Schr\"odinger equation for an atomic beam predicts that it must have a
phase anomaly near the beam waist analogous to the Gouy phase of an
electromagnetic beam. We propose here a feasible experiment which allows for
the direct determination of this anomalous phase using Ramsey interferometry
with Rydberg atoms. Possible experimental limitations are discussed and shown
to be completely under control within the present day technology. We also
discuss how this finding can open the possibility to use the spatial mode
wavefunctions of atoms as q-dits, since the Gouy phase is an essential
ingredient for making rotations in the quantum states.Comment: 9 pages and 3 figure
Anti-Inflammatory Cytokines Predominate in Acute Human Plasmodium knowlesi Infections
Plasmodium knowlesi has entered the human population of Southeast Asia. Naturally acquired knowlesi malaria is newly described with relatively little available data, including data on the host response to infection. Therefore pre-treatment cytokine and chemokine profiles were determined for 94 P. knowlesi, and for comparison, 20, P. vivax and 22 P. falciparum, patients recruited in Malaysian Borneo. Nine, five and one patient with P. knowlesi, P. falciparum and P. vivax respectively had complicated malaria as defined by World Health Organisation. Patients with uncomplicated P. knowlesi had lower levels of the pro-inflammatory cytokines IL-8 and TNFα than those with complicated disease (both p<0.05, Dunn's post test, DPT). The anti-inflammatory cytokines IL-1ra and IL-10 were detected in all patients in the study. IL-1ra, the most abundant cytokine measured, correlated with parasitaemia in P. knowlesi (rs = 0.47, p =  <0.0001), P. vivax (rs = 0.61, p = 0.0042) and P. falciparum (rs = 0.57,p = 0.0054) malaria. IL-10 correlated with parasitaemia in both P. knowlesi (rs = 0.54, p =  <0.0001) and P. vivax (rs = 0.78, p =  <0.0001) infections. There were between group differences in soluble markers of macrophage activation (MIP-1β and MCP-1). P. knowlesi patients had significantly lower levels of MIP-1β than P. falciparum (DPT, p =  <0.01). Uncomplicated P. knowlesi patients had significantly lower levels of MCP-1 than uncomplicated P. falciparum patients (DPT, p =  <0.001). There was no significant difference between complicated and uncomplicated P. knowlesi infections. MCP-1, MIP-1β, IL-8 and TNFα increased in complicated P. knowlesi but decreased in complicated P. falciparum infections. Descriptions of human knowlesi malaria provide a comparative means to discover mediators of pathophysiology in severe P. knowlesi as well as P. falciparum malaria. Crucially, P. knowlesi may be the disease and experimental primate model for severe malaria
Roadmap on structured light
Structured light refers to the generation and application of custom light fields. As the tools and technology to create and detect structured light have evolved, steadily the applications have begun to emerge. This roadmap touches on the key fields within structured light from the perspective of experts in those areas, providing insight into the current state and the challenges their respective fields face. Collectively the roadmap outlines the venerable nature of structured light research and the exciting prospects for the future that are yet to be realized
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