15,936 research outputs found
An update on the correlation between the cosmic radiation intensity and the geomagnetic AA index
A statistical study between the cosmic ray intensity, as observed by a neutron monitor, and of the geomagnetic aa index, as representative of perturbations in the plasma and interplanetary magnetic field in the heliosphere, has been updated to specifically exclude time periods around the reversal of the solar magnetic field. The results of this study show a strong negative correlation for the period 1960 through 1968 with a correlation coefficient of approximately -0.86. However, there is essentially no correlation between the cosmic ray intensity and the aa index for the period 1972-1979 (i.e. correlation coefficient less than 0.16). These results would appear to support the theory of preferential particle propagation into the heliosphere vis the ecliptic during the period 1960-1968 and via the solar polar regions during 1972-1979
Unusual light spectra from a two-level atom in squeezed vacuum
We investigate the interaction of an atom with a multi-channel squeezed
vacuum. It turns out that the light coming out in a particular channel can have
anomalous spectral properties, among them asymmetry of the spectrum, absence of
the central peak as well as central hole burning for particular parameters. As
an example plane-wave squeezing is considered. In this case the above phenomena
can occur for the light spectra in certain directions. In the total spectrum
these phenomena are washed out.Comment: 16 pages, LaTeX, 3 figures (included via epsf
Quantum Hall Ferrimagnetism in lateral quantum dot molecules
We demonstrate the existance of ferrimagnetic and ferromagnetic phases in a
spin phase diagram of coupled lateral quantum dot molecules in the quantum Hall
regime. The spin phase diagram is determined from Hartree-Fock Configuration
Interaction method as a function of electron numbers N, magnetic field B,
Zeeman energy, and tunneling barrier height. The quantum Hall ferrimagnetic
phase corresponds to spatially imbalanced spin droplets resulting from strong
inter-dot coupling of identical dots. The quantum Hall ferromagnetic phases
correspond to ferromagnetic coupling of spin polarization at filling factors
between and .Comment: 4 pages, 4 figure
Preparation of an Exciton Condensate of Photons on a 53-Qubit Quantum Computer
Quantum computation promises an exponential speedup of certain classes of
classical calculations through the preparation and manipulation of entangled
quantum states. So far most molecular simulations on quantum computers,
however, have been limited to small numbers of particles. Here we prepare a
highly entangled state on a 53-qubit IBM quantum computer, representing 53
particles, which reveals the formation of an exciton condensate of photon
particles and holes. While elusive for more than 50 years, such condensates
were recently achieved for electron-hole pairs in graphene bilayers and metal
chalcogenides. Our result with a photon condensate has the potential to further
the exploration of this new form of condensate that may play a significant role
in realizing efficient room-temperature energy transport
Racialised prescribing: enacting race/ethnicity in clinical practice guidelines and in accounts of clinical practice
This paper examines the articulation and enactment of racialised classifications in clinical practice guidelines and in accounts of clinical practice. It contributes to debates about racialisation in medicine and its consequences. The research centred on the case study of prescribing guidelines for hypertension in England and Wales, drawing on documentary sources and semi-structured expert interviews. We found that conceptual and socio-political uncertainties existed about how to interpret the designation ‘black patients’ and about the practices for identifying patients’ race/ethnicity. To ‘close’ uncertainties, and thus produce the guidelines and treat patients, respondents drew authority from disparate elements of the ‘topologies of race’. This has implications for understanding processes of racialisation and for the future use of racialised clinical practice guidelines. We argue that clinical practice guidelines play a ‘nodal’ role in racialisation by forming an authoritative material connection that creates a path for translating racialised research into racialised healthcare practice, and that they carry with them implicit conceptual and socio-political uncertainties that are liable to create inconsistencies in healthcare practice
Research study of droplet sizing technology leading to the development of an advanced droplet sizing system
An instrument to measure the size and velocity of droplets was developed. The instrument uses one of two techniques, as appropriate. In the first technique two small laser beams of one color identify the center of a larger laser beam of a different color. This defines a region of almost uniform intensity where the light scattered by the individual droplets can be related to their size. The first technique uses the visibility of a Doppler burst and validates it against the peak intensity of the signal's pedestal. Results are presented for monodisperse, bimodal, trimodal, and polydisperse sprays produced by the Berglund-Liu droplet generator and a pressure nozzle. Size distributions of a given spray obtained using three different size ranges show excellent self-consistency in the overlapping region. Measurements of sprays of known characteristics exhibit errors in the order of 10%. The principles of operation and design criteria of the instrument are discussed in great detail
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