3,029 research outputs found
New CP-violation and preferred-frame tests with polarized electrons
We used a torsion pendulum containing polarized
electrons to search for CP-violating interactions between the pendulum's
electrons and unpolarized matter in the laboratory's surroundings or the sun,
and to test for preferred-frame effects that would precess the electrons about
a direction fixed in inertial space. We find and for AU. Our preferred-frame constraints, interpreted in
the Kosteleck\'y framework, set an upper limit on the parameter eV that should be compared to the benchmark
value eV.Comment: 4 figures, accepted for publication in Physical Review Letter
Genomic Scans Support Repetitive Continental Colonization Events during the Rapid Radiation of Voles (Rodentia: Microtus): the Utility of AFLPs versus Mitochondrial and Nuclear Sequence Markers
Single locus studies might not resolve phylogenetic relationships and the evolutionary history of taxa. The analysis of multiple markers promises higher resolution, and congruence among loci may indicate that the phylogenies represent the underlying species history. Here, we examine the utility of a genome-wide approach based on amplified fragment length polymorphisms (AFLP) and several DNA sequence markers in resolving phylogenetic signals in the rapidly radiating rodent genus Microtus which produced about 70 vole species within the last 1.2-2 myr. The current Holarctic distribution of Microtus is assumed to have resulted from three independent colonization events out of Asia to North America, Europe, and northern Asia without subsequent colonization, which would have led to deep splits between species from different continents. We investigated this hypothesis of three single colonization events by reconstructing the phylogenetic relationships among species from all three continents based on data from the first exon of the nuclear arginine vasopressin receptor 1a gene (EXON1), an adjacent noncoding region and the mitochondrial cytochrome b gene. The phylogenetic patterns obtained from these sequence markers are contrasted to genome-wide data on more than 1800 amplified fragment length polymorphisms (AFLP) analyzed for the same samples. Our results show that the single sequence markers partially resolve the phylogenetic relationships within Microtus, but with some incongruence mostly between EXON1 and the other loci. However, deeper nodes of the radiation are only weakly supported and neither the combination of the markers nor additional nuclear sequences improved the resolution significantly. AFLPs provided much stronger support for major continent-specific clades, and show also that reciprocal monophyly of American and European voles is incomplete. Our results demonstrate that Microtus voles colonized the American and European continents each repeatedly in several independent events on similar colonization routes during their radiation. More generally, this study supports the suitability of AFLPs as an alternative to sequence markers to resolve the evolutionary history of rapidly radiating tax
To Fib or Not to Fib: Misdiagnosis of Atrial Fibrillation on Telemetry Case Presentation and Root Cause Analysis
Case presentation, current practices of telemetry management, root cause analysis, goals for improvement, proposed intervention and next steps
Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale
We conducted three torsion-balance experiments to test the gravitational
inverse-square law at separations between 9.53 mm and 55 micrometers, probing
distances less than the dark-energy length scale m. We find with 95% confidence
that the inverse-square law holds () down to a length scale
m and that an extra dimension must have a size m.Comment: 4 pages, 6 figure
Measurement of Linear Stark Interference in 199Hg
We present measurements of Stark interference in the 6
6 transition in Hg, a process whereby a static electric field
mixes magnetic dipole and electric quadrupole couplings into an electric
dipole transition, leading to -linear energy shifts similar to those
produced by a permanent atomic electric dipole moment (EDM). The measured
interference amplitude, = = (5.8 1.5) (kV/cm), agrees with relativistic, many-body predictions and
confirms that earlier central-field estimates are a factor of 10 too large.
More importantly, this study validates the capability of the Hg EDM
search apparatus to resolve non-trivial, controlled, and sub-nHz Larmor
frequency shifts with EDM-like characteristics.Comment: 4 pages, 4 figures, 1 table; revised in response to reviewer comment
Spin-Dependent Macroscopic Forces from New Particle Exchange
Long-range forces between macroscopic objects are mediated by light particles
that interact with the electrons or nucleons, and include spin-dependent static
components as well as spin- and velocity-dependent components. We parametrize
the long-range potential between two fermions assuming rotational invariance,
and find 16 different components. Applying this result to electrically neutral
objects, we show that the macroscopic potential depends on 72 measurable
parameters. We then derive the potential induced by the exchange of a new gauge
boson or spinless particle, and compare the limits set by measurements of
macroscopic forces to the astrophysical limits on the couplings of these
particles.Comment: 37 page
Improved limit on the permanent electric dipole moment of 199Hg
We report the results of a new experimental search for a permanent electric
dipole moment of 199Hg utilizing a stack of four vapor cells. We find d(199Hg)
= (0.49 \pm 1.29_stat \pm 0.76_syst) x 10^{-29} e cm, and interpret this as a
new upper bound, |d(199Hg)| < 3.1 x 10^{-29} e cm (95% C.L.). This result
improves our previous 199Hg limit by a factor of 7, and can be used to set new
constraints on CP violation in physics beyond the standard model.Comment: 4 pages, 4 figures. additional reference, minor edits in response to
reviewer comment
Leveraging Semantic Web Service Descriptions for Validation by Automated Functional Testing
Recent years have seen the utilisation of Semantic Web Service descriptions for automating a wide range of service-related activities, with a primary focus on service discovery, composition, execution and mediation. An important area which so far has received less attention is service validation, whereby advertised services are proven to conform to required behavioural specifications. This paper proposes a method for validation of service-oriented systems through automated functional testing. The method leverages ontology-based and rule-based descriptions of service inputs, outputs, preconditions and effects (IOPE) for constructing a stateful EFSM specification. The specification is subsequently utilised for functional testing and validation using the proven Stream X-machine (SXM) testing methodology. Complete functional test sets are generated automatically at an abstract level and are then applied to concrete Web services, using test drivers created from the Web service descriptions. The testing method comes with completeness guarantees and provides a strong method for validating the behaviour of Web services
Approaches to land snail shell bead manufacture in the Early Holocene of Malawi
Shell disc beads are important archeological indicators of social communication and exchange networks. There has been substantial research on ostrich eggshell (OES) beads, but little is known about the manufacture or chronology of similar beads from land snail shells (LSS). LSS beads are associated with Holocene hunter-gatherers in Africa, though direct dates are limited to the Iron Age, and there are no images or descriptions of the manufacturing sequence. Here, we combine experimental and archeological data to resolve the chronology, operational chains, and material properties of LSS bead manufacture. We then recommend and apply a modified OES production sequence to three Later Stone Age assemblages from the Kasitu Valley of northern Malawi (Hora 1, Mazinga 1, and Kadawonda 1). At these sites, LSS shows an unexpectedly high proportion of Pathway 2 manufacture (disc shaping prior to perforation), in direct contrast with known OES bead manufacture. Application of red color occurred at all stages of manufacture, albeit inconsistently. Production of finished beads involved substantial removal of material from preforms to create the final product. Finally, we report the earliest evidence for LSS bead manufacture with two directly dated preforms (~ 9500 cal BP), showing that the origins of LSS beadmaking do precede the Iron Age.Introduction Background and previous research - The problem of land snail disc beads - Land snail shell versus ostrich eggshell Materials and methods - Experimental methods -- Breakage -- Shaping -- Drilling -- Pigments - Archeological samples -- Site descriptions -- Recovery protocols -- Sorting, data collection, and analysis -- Dating Results - Experimental results -- Breakage -- Shaping -- Drilling -- Production stages specific to LSS -- Application of pigments - Archeological results -- Assemblage description -- Manufacturing chains -- Dating Discussion Conclusion
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