3,425 research outputs found
Ultra--cold gases and the detection of the Earth's rotation: Bogoliubov space and gravitomagnetism
The present work analyzes the consequences of the gravitomagnetic effect of
the Earth upon a bosonic gas in which the corresponding atoms have a
non--vanishing orbital angular momentum. Concerning the ground state of the
Bogoliubov space of this system we deduce the consequences, on the pressure and
on the speed of sound, of the gravitomagnetic effect. We prove that the effect
on a single atom is very small, but we also show that for some thermodynamical
properties the consequences scale as a non--trivial function of the number of
particles.Comment: 4 page
Performance of Geant4 in simulating semiconductor particle detector response in the energy range below 1 MeV
Geant4 simulations play a crucial role in the analysis and interpretation of
experiments providing low energy precision tests of the Standard Model. This
paper focuses on the accuracy of the description of the electron processes in
the energy range between 100 and 1000 keV. The effect of the different
simulation parameters and multiple scattering models on the backscattering
coefficients is investigated. Simulations of the response of HPGe and
passivated implanted planar Si detectors to \beta{} particles are compared to
experimental results. An overall good agreement is found between Geant4
simulations and experimental data
Integrated stratigraphy of the Waitakian-Otaian Stage boundary stratotype, Early Miocene, New Zealand
The base of the type section of the Otaian Stage at Bluecliffs, South Canterbury, is recognised as the stratotype for the boundary between the Waitakian and Otaian Stages. Principal problems with the boundary are the restriction of existing bioevent proxies to shelf and upper slope environments and its uncertain age. These topics are addressed by a multidisplinary study of a 125 m section about the boundary, which examines its lithostratigraphy, depositional setting, biostratigraphy, correlation, and geochronology.
The lower siltstone lithofacies (0-38.5 m) was deposited at upper bathyal depths (200-600 m) in a marginal basin which was partially sheltered from fully oceanic circulation by a submarine high and islands. The site was covered by cool-temperate water and was probably adjacent to the Subtropical Convergence. This unit is succeeded by the banded lithofacies (38.5-106 m) and the upper siltstone lithofacies (basal 19 m studied). Paleodepth probably declined up-sequence, but deposition at shelf depths is not definitely indicated. A cyclic pattern of abundance spikes in benthic and planktonic foraminifera commences 9 m above base and extends to 73 m in the banded lithofacies. Oxygen isotope excursions (up to 2.08%) in Euuvigerina miozea and Cibicides novozelandicus are greatest within the interval containing the abundance spikes. The stage boundary occurs in the banded lithofacies at the highest abundance spike (73 m). Although condensed intervals might affect the completeness of the section, they are not associated with sedimentary discontinuities, and we consider that the section is suitable as a biostratigraphic reference.
Spores, pollens, dinoflagellates, calcareous nannofossils, foraminifera, bryozoans, and ostracods are preserved near the boundary, but molluscs principally occur higher, in the shallower upper siltstone lithofacies. Siliceous microfossils are rare. There is considerable scope for further biostratigraphic research.
The primary event marking the boundary at 73 m is the appearance of the benthic foraminifer Ehrenbergina marwicki. This is a distinctive and widely distributed event but is restricted to shelf and upper bathyal environments. Supplementary events in planktonic foraminifera and calcareous nannofossils were researched. Highest occurrences of Globigerina brazieri and G. euapertura are recorded at 47 and 58 m. There is a marked decline in relative abundance of Paragloborotalia spp. at 62 m. Helicosphaera carteri becomes more abundant than H. euphratis between 56 and 87 m. These events are not exact proxies for the boundary but they may usefully indicate proximity to it. They occur in the interval of prominent spikes in foraminiferal abundance.
The Waitakian-Otaian boundary is dated at 21.7 Ma by strontium isotopes. Stable primary remanence could not be determined in a pilot paleomagnetic study of Bluecliffs specimens. However, specimens trended towards reversed polarity, and remagnetisation great circle analysis will allow directions to be calculated in future collections
Moving towards 100% renewable electricity in Europe & North Africa by 2050
In spring 2010, European and international climate experts at PwC, the European Climate Forum, the Potsdam Institute for Climate Impact Research and the International Institute for Applied System Analysis published 100% Renewable Electricity - A roadmap to 2050 for Europe and North Africa. The report examined the potential for powering Europe and North Africa with renewable electricity exclusively by 2050. It set out a series of financial, market, infrastructure and government policy steps that would need to occur if such a "what if" vision was to be achieved.
Now, a year on, this latest report provides a complementary analysis to the original roadmap. PwC, the Potsdam Institute for Climate Impact Research and the International Institute for Applied System Analysis, look at whether the vision of 100% renewable electricity has moved closer or further away as a result of current and recent developments over the last 12 months. The report, intended to support the wider debate in this area, examines five areas that are most critical to achieving progress and, through the lens of these five areas, looks at the impact of recent and current events
Comparison of Transfer-to-Continuum and Eikonal Models of Projectile Fragmentation Reactions
Spectroscopic properties of nuclei are accessible with projectile
fragmentation reactions, but approximations made in the reaction theory can
limit the accuracy of the determinations. We examine here two models that have
rather different approximations for the nucleon wave function, the target
interaction, and the treatment of the finite duration of the reaction. The
nucleon-target interaction is treated differently in the eikonal and the
transfer-to-continuum model, but the differences are more significant for light
targets. We propose a new parameterization with that in mind. We also propose a
new formula to calculate the amplitude that combines the better treatment of
the wave function in the eikonal model with the better treatment of the target
interaction in the transfer-to-continuum model.Comment: 21 pages, latex file including 3 tables. 5 figures. Submitted to
Phys. Rev.
Visuocognitive Fluency Facilitating ECG Interpretation with Visual Metaphors and Expressive Tags
Immorality and Irrationality
Does immorality necessarily involve irrationality? The question is often taken to be among the deepest in moral philosophy. But apparently deep questions sometimes admit of deflationary answers. In this case we can make way for a deflationary answer by appealing to dualism about rationality, according to which there are two fundamentally distinct notions of rationality: structural rationality and substantive rationality. I have defended dualism elsewhere. Here, I’ll argue that it allows us to embrace a sensible – I will not say boring – moderate view about the relationship between immorality and irrationality: roughly, that immorality involves substantive irrationality, but not structural irrationality. I defend this moderate view, and argue that many of the arguments for less moderate views turn either on missing the distinction between substantive and structural rationality, or on misconstruing it
Measurement of the -asymmetry parameter of Cu in search for tensor type currents in the weak interaction
Precision measurements at low energy search for physics beyond the Standard
Model in a way complementary to searches for new particles at colliders. In the
weak sector the most general decay Hamiltonian contains, besides vector
and axial-vector terms, also scalar, tensor and pseudoscalar terms. Current
limits on the scalar and tensor coupling constants from neutron and nuclear
decay are on the level of several percent.
The goal of this paper is extracting new information on tensor coupling
constants by measuring the -asymmetry parameter in the pure Gamow-Teller
decay of Cu, thereby testing the V-A structure of the weak interaction.
An iron sample foil into which the radioactive nuclei were implanted was cooled
down to milliKelvin temperatures in a He-He dilution refrigerator. An
external magnetic field of 0.1 T, in combination with the internal hyperfine
magnetic field, oriented the nuclei. The anisotropic radiation was
observed with planar high purity germanium detectors operating at a temperature
of about 10\,K. An on-line measurement of the asymmetry of Cu
was performed as well for normalization purposes. Systematic effects were
investigated using Geant4 simulations.
The experimental value, = 0.587(14), is in agreement with the
Standard Model value of 0.5991(2) and is interpreted in terms of physics beyond
the Standard Model. The limits obtained on possible tensor type charged
currents in the weak interaction hamiltonian are -0.045
0.159 (90\% C.L.). The obtained limits are comparable to limits from other
correlation measurements in nuclear decay and contribute to further
constraining tensor coupling constants
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