Search results for "Coherence"

Probing mechanical quantum coherence with an ultracold-atom meter

2011

We propose a scheme to probe quantum coherence in the state of a nano-cantilever based on its magnetic coupling (mediated by a magnetic tip) with a spinor Bose Einstein condensate (BEC). By mapping the BEC into a rotor, its coupling with the cantilever results in a gyroscopic motion whose properties depend on the state of the cantilever: the dynamics of one of the components of the rotor angular momentum turns out to be strictly related to the presence of quantum coherence in the state of the cantilever. We also suggest a detection scheme relying on Faraday rotation, which produces only a very small back-action on the BEC and it is thus suitable for a continuous detection of the cantilever'…

Sterile Neutrinos in Light of Recent Cosmological and Oscillation Data: a Multi-Flavor Scheme Approach

2008

Light sterile neutrinos might mix with the active ones and be copiously produced in the early Universe. In the present paper, a detailed multi-flavor analysis of sterile neutrino production is performed. Making some justified approximations allows us to consider not only neutrino interactions with the primeval medium and neutrino coherence breaking effects, but also oscillation effects arising from the presence of three light (mostly-active) neutrino states mixed with two heavier (mostly-sterile) states. First, we emphasize the underlying physics via an analytical description of sterile neutrino abundances that is valid for cases with small mixing between active and sterile neutrinos. Then,…

In-medium jet shape from energy collimation in parton showers: Comparison with CMS PbPb data at 2.76 TeV

2014

Abstract: We present the medium-modified energy collimation in the leading-logarithmic approximation (LLA) and next-to-leading-logarithmic approximation (NLLA) of QCD. As a consequence of more accurate kinematic considerations in the argument of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) fragmentation functions (FFs) we find a new NLLA correction O ð α s Þ which accounts for the scaling violation of DGLAP FFs at small x . The jet shape is derived from the energy collimation within the same approximations and we also compare our calculations for the energy collimation with the event generators PYTHIA 6 and Y A JEM for the first time in this paper. The modification of jets by the …

Quasi-decadal signals of Sahel rainfall and West African monsoon since the mid-twentieth century

2013

[1] Sahel rainfall shows pronounced decadal variability and a negative trend between wet conditions in the 1950s–1960s and dry ones in the 1970s–1980s. Using continuous wavelet transform, the quasi-decadal variability (QDV) of rainfall reveals zonal contrasts. The highest QDV is identified in the 1950s–1960s over western Sahel and in the 1970s–1980s over eastern Sahel. The quasi-decadal atmospheric anomalies have been reconstructed using Fourier transform for the 1950s–1960s and the 1970s–1980s, respectively, and assessed by the composite analysis of the QDV phases for the periods before and after 1968. Over western Sahel, the rainfall QDV in the 1950s–1960s is related to the North Atlantic…

Spatial coherence and potential predictability assessment of intraseasonal statistics of wet and dry spells over Equatorial Eastern Africa

2012

The aim of this study was to derive components of the intraseasonal rainfall variations from the daily rainfall in the Equatorial Eastern Africa region and assess their spatial coherence, a pointer to their potential predictability. Daily rainfall observations from 36 stations distributed over Equatorial Eastern Africa and extending from 1962 to 2000 were used. The March to May and October to December periods commonly referred to as the long and short rainfall seasons respectively were considered. Seasonal and intraseasonal statistics at the local (station) level were first defined. The stations were also grouped into near-homogeneous (sub-regional) zones based on daily rainfall. Similarly,…

Coherence and entanglement dynamics of vibrating qubits

2017

We investigate the dynamics of coherence and entanglement of vibrating qubits. Firstly, we consider a single trapped ion qubit inside a perfect cavity and successively we use it to construct a bipartite system made of two of such subsystems, taken identical and noninteracting. As a general result, we find that qubit vibration can lead to prolonging initial coherence in both single-qubit and two-qubit system. However, despite of this coherence preservation, we show that the decay of the entanglement between the two qubits is sped up by the vibrational motion of the qubits. Furthermore, we highlight how the dynamics of photon-phonon correlations between cavity mode and vibrational mode, which…

THE INFLUENCE OF SPATIAL COGNITION IN THEORY OF MIND AND CENTRAL COHERENCE TASKS: STUDY IN AUTISM

Autism Spectrum Disorder (ADS) is a severe developmental disability characterized by impairments in social interaction and communicative skills. Despite a growing research interest in the field, the causes of these impairments remain unknown. Two lines of research, Theory of Mind (ToM) and Central Coherence (CC), using experimental tasks such as visuo-spatial perspective Taking (VPT) and the local and global levels have suggested that visuo-spatial attention and spatial variables in the self-versus other recognition, may be the basis of the cognitive processes underlying social interaction. According to spatial attention, such as observed in the Unilateral spatial neglect (USN) may contribu…

Probabilities of conditionals and previsions of iterated conditionals

2019

Abstract We analyze selected iterated conditionals in the framework of conditional random quantities. We point out that it is instructive to examine Lewis's triviality result, which shows the conditions a conditional must satisfy for its probability to be the conditional probability. In our approach, however, we avoid triviality because the import-export principle is invalid. We then analyze an example of reasoning under partial knowledge where, given a conditional if A then C as information, the probability of A should intuitively increase. We explain this intuition by making some implicit background information explicit. We consider several (generalized) iterated conditionals, which allow…

Ocular biometry with swept-source optical coherence tomography

2020

This study aimed to summarize the outcomes reported when swept-source optical coherence tomography (SS-OCT) is used for ocular biometry. A literature search was performed to identify publications reporting clinical outcomes of patients measured with commercial SS-OCT. Twenty-nine studies were included in this review. A comprehensive analysis of the available data was performed, focusing on parameters used for intraocular lens (IOL) power calculation in cataract surgery, including keratometry, central corneal thickness, white-to-white distance, anterior chamber depth, lens thickness, axial length, IOL power, and pupil diameter. Different metrics for repeatability, reproducibility, and agreem…

Evaluation of 6 biometers based on different optical technologies

2021

This study shows that optical biometers based on different technologies provide repeatable measurements for different ocular parameters and, when compared, statistically significant differences between them were found when measuring most parameters.