3,854 research outputs found
Astrophysical and Cosmological Tests of Quantum Theory
We discuss several proposals for astrophysical and cosmological tests of
quantum theory. The tests are motivated by deterministic hidden-variables
theories, and in particular by the view that quantum physics is merely an
effective theory of an equilibrium state. The proposed tests involve searching
for nonequilibrium violations of quantum theory in: primordial inflaton
fluctuations imprinted on the cosmic microwave background, relic cosmological
particles, Hawking radiation, photons with entangled partners inside black
holes, neutrino oscillations, and particles from very distant sources.Comment: 25 pages. Amendment to section 7. Contribution to: "The Quantum
Universe", special issue of Journal of Physics A, dedicated to Prof. G.-C.
Ghirardi on the occasion of his seventieth birthda
Cepstral analysis based on the Glimpse proportion measure for improving the intelligibility of HMM-based synthetic speech in noise
In this paper we introduce a new cepstral coefficient extraction method based on an intelligibility measure for speech in noise, the Glimpse Proportion measure. This new method aims to increase the intelligibility of speech in noise by modifying the clean speech, and has applications in scenarios such as public announcement and car navigation systems. We first explain how the Glimpse Proportion measure operates and further show how we approximated it to integrate it into an existing spectral envelope parameter extraction method commonly used in the HMM-based speech synthesis framework. We then demonstrate how this new method changes the modelled spectrum according to the characteristics of the noise and show results for a listening test with vocoded and HMM-based synthetic speech. The test indicates that the proposed method can significantly improve intelligibility of synthetic speech in speech shaped noise. Index Terms â cepstral coefficient extraction, objective measure for speech intelligibility, Lombard speech, HMM-based speech synthesis 1
Inflationary Cosmology as a Probe of Primordial Quantum Mechanics
We show that inflationary cosmology may be used to test the statistical
predictions of quantum theory at very short distances and at very early times.
Hidden-variables theories, such as the pilot-wave theory of de Broglie and
Bohm, allow the existence of vacuum states with non-standard field fluctuations
('quantum nonequilibrium'). We show that inflationary expansion can transfer
microscopic nonequilibrium to macroscopic scales, resulting in anomalous power
spectra for the cosmic microwave background. The conclusions depend only weakly
on the details of the de Broglie-Bohm dynamics. We discuss, in particular, the
nonequilibrium breaking of scale invariance for the primordial (scalar) power
spectrum. We also show how nonequilibrium can generate primordial perturbations
with non-random phases and inter-mode correlations (primordial
non-Gaussianity). We address the possibility of a low-power anomaly at large
angular scales, and show how it might arise from a nonequilibrium suppression
of quantum noise. Recent observations are used to set an approximate bound on
violations of quantum theory in the early universe.Comment: 44 pages. Minor changes in v
Postural control deficit during Sit-To-Walk in patients with Parkinson\u2019s Disease and Freezing of Gait
Introduction
The intricate linkage between Freezing of Gait (FoG) and postural control in Parkinson's disease (PD) is unclear. We analyzed the impact of FoG on dynamic postural control.
Methods
24 PD patients, 12 with (PD\u202f+\u202fFoG), 12 without FoG (PD-FoG), and 12 healthy controls, were assessed in ON state. Mobility and postural control were measured with clinical scales (UPDRS III, BBS, MPAS) and with kinematic and kinetic analysis during three tasks, characterized by levels of increasing difficulty to plan sequential movement of postural control: walk (W), gait initiation (GI) and sit-to-walk (STW).
Results
The groups were balanced by age, disease duration, disease severity, mobility and balance. During STW, the spatial distribution of COP trajectories in PD\u202f+\u202fFoG patients are spread over medial-lateral space more than in the PD-FoG (p\u202f<\u202f.001). Moreover, the distribution of COP positions. in the transition between sit-to-stand and gait initiation, is not properly shifted toward the leading leg, as in PD-FoG and healthy controls, but it is more centrally dispersed (p\u202f<\u202f.01) with a delayed weight forward progression (p\u202f<\u202f.05). In GI task and walk task, COM and COP differences are less evident and even absent between PD patients.
Conclusion
PD\u202f+\u202fFoG show postural control differences in STW, compared with PD-FoG and healthy. Different spatial distribution of COP trajectories, between two PD groups are probably due to a deficit to plan postural control during a more demanding motor pattern, such as STW
Soil is a net source of methane in tropical African forests
Research Highlights: Monitoring of soil CH4 fluxes in African tropical forest conducted run for almost two years, contributing to the scant information on greenhouse gas (GHG) fluxes from forests available from this region. Data showed that the forest soil acted as a net yearly source of CH4. Hotspots of CH4 emissions were measured both in upland and lowland areas of the forest, and on an annual basis they overcame the soil CH4 sink during drier periods or in wellâdrained areas. Background and Objectives: Atmospheric studies indicate that tropics are a strong CH4 source. Regional budgets attribute the majority of this source to wetland ecosystems and flooded lowland forests, whereas unâflooded forests are considered net CH4 sinks, although few studies in tropical forests, in particular in Africa, are available. The present work aims to contribute to this knowledge gap. Materials and Methods: Monitoring campaigns were conducted along the year in the tropical forest of the Ankasa National Park, Ghana, in two contrasting environments, uphill and downhill, using close static chambers coupled with gas chromatography. Results: The uphill area was a net weak CH4 sink with mean daily fluxes ranging from â1.29 to 0.44 mg CH4 mâ2 dâ1. The downhill area was a significant CH4 source with mean daily fluxes ranging from â0.67 to 188.09 mg CH4 mâ2 dâ1 and with peaks up to 1312 mg CH4 mâ2 dâ1 in the wet season. Conclusions: The net annual soil CH4 budget for the Ankasa Park, normalizing the proportion of downhill areas over the whole park surface, was a source of about 3.3 kg CH4 haâ1 yrâ1. Overlooking such areas might lead to underestimates of the total CH4 source strength of forested areas
Does degradation from selective logging and illegal activities differently impact forest resources? A case study in Ghana
Degradation, a reduction of the ecosystemâs capacity to supply goods and services, is widespread in tropical forests and mainly caused by human disturbance. To maintain the full range of forest ecosystem services and support the development of effective conservation policies, we must understand the overall impact of degradation on different forest resources. This research investigates the response to disturbance of forest structure using several indicators: soil carbon content, arboreal richness and biodiversity, functional composition (guild and wood density), and productivity. We drew upon large field and remote sensing datasets from different forest types in Ghana, characterized by varied protection status, to investigate impacts of selective logging, and of illegal land use and resources extraction, which are the main disturbance causes in West Africa. Results indicate that functional composition and the overall number of species are less affected by degradation, while forest structure, soil carbon content and species abundance are seriously impacted, with resources distribution reflecting the protection level of the areas. Remote sensing analysis showed an increase in productivity in the last three decades, with higher resiliency to change in drier forest types, and stronger productivity correlation with solar radiation in the short dry season. The study region is affected by growing anthropogenic pressure on natural resources and by an increased climate variability: possible interactions of disturbance with climate are also discussed, together with the urgency to reduce degradation in order to preserve the full range of ecosystem functions
Review about comorbidities of behavioural disorders in children and adolescents: The focus on attention-deficit/hyperactivity disorder
Disruptive behavior disorders (DBD) present high comorbidity rate mainly for opposite-defiant disorders that are frequent among children, adolescents and adults affected by with attention deficit and hyperactivity disorder (ADHD), probably as result of common temperamental risk factors such as attention, distraction, impulsivity. ADHD tend to manifest in about 50% of individuals diagnosed as disruptive behavioral disorders
Behavioural disorders in children and adolescents: A conceptual review about the therapeutic alliance with family and school
Aim: In disruptive behavioral disorders, given the wide range of symptomatic manifestations and the complexity of the sociofamiliar contexts in which they develop, it is now proven that more visible and more stable results can be achieved over time through multimodal and multidimensional interventions. These are accomplished through the integration of psychotherapeutic interventions for the child and parents, counseling interventions for all the various practitioners who come into contact with the child in school, sports, and social settings, through the possibility of organizing multiple settings in patient can be followed by several health professionals such as child and adolescent neuropsychiatrist, neuropsychomotricist, occupation therapist, psychologist
Bell's Jump Process in Discrete Time
The jump process introduced by J. S. Bell in 1986, for defining a quantum
field theory without observers, presupposes that space is discrete whereas time
is continuous. In this letter, our interest is to find an analogous process in
discrete time. We argue that a genuine analog does not exist, but provide
examples of processes in discrete time that could be used as a replacement.Comment: 7 pages LaTeX, no figure
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