5,948 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 — cepstral coefficient extraction, objective measure for speech intelligibility, Lombard speech, HMM-based speech synthesis 1
ГЛОБАЛЬНАЯ АГРОПРОМЫШЛЕННАЯ СИСТЕМА И ИЗМЕНЕНИЕ КЛИМАТА: ВЫЗОВЫ И ВОЗМОЖНОСТИ ДЛЯ РОССИЙСКОЙ ФЕДЕРАЦИИ
The article examines the dependence of the development of the global agricultural system against climate change of the planet. It is argued that agricultural production in the period beyond 2015 is playing an increasingly prominent role, and it will increase in future. The current vulnerability of climate system largely depends on a delicate balance between greenhouse gas emissions caused by human activities, a policy aimed at mitigating these harmful effects and the natural dynamics of the functioning of terrestrial and ocean systems. This, in turn, depends on the number of sources of greenhouse gases that affect climate. Unprecedented climate change seriously threatens agricultural production and food security. It is therefore essential the further development of new areas of science, including a reliable methodology for monitoring greenhouse gases, advanced modeling tools, collection and aggregation of big data. Despite the good preconditions for the development of the food sector, the risk of impacts of climate change on natural ecosystems remains high, even under favorable temperature conditions. Thus, solutions must be found in the change of our paradigms.We must change the attitude towards agriculture as a separate component of the food system. Agriculture should be an important element in mitigating the effects of climate change and adaptive strategies. The author argues that Russia is a promising candidate among the boreal regions. Russia is able to take advantage of the situation and to turn from an importer of agricultural products into solid world exporter of food. The article presents several factors that can become the basis for a new agricultural and food strategy of Russia. But to fully take advantage of such capabilities it is required significant transformation. Taking into account some changes in the agricultural sector, the author provides recommendations that could enhance the role of the Russian Federation on the agrofood world markets.В статье анализируется зависимость развития глобальной агропромышленной системы от изменения климата планеты. Утверждается, что сельскохозяйственное производство в период после 2015 г. играет все более заметную роль, и в дальнейшем она будет усиливаться. При этом нынешняя уязвимость климатической системы во многом зависит от тонкого баланса между выбросами парниковых газов, вызванных деятельностью человека, политикой смягчения этих пагубных последствий и естественной динамикой функционирования земных и океанских систем. Это, в свою очередь, зависит от количества источников парниковых газов, оказывающих влияние на климат. Беспрецедентное изменение климата серьезно угрожает производству сельско-хозяйственной продукции и продовольственной безопасности. Поэтому крайне важно дальнейшее развитие новых направлений науки, включающих в себя надежные методологии мониторинга парниковых газов, передовые инструменты моделирования, сбора и статистической обработки больших данных. Несмотря на хорошие предпосылки для развития продовольственного сектора, риск воздействия климатических изменений на природные экосистемы остается высоким, даже при наличии благоприятных температурных условий. Таким образом, решения должны быть найдены в изменении наших парадигм. Мы должны изменить отношение к сельскому хозяйству как к отдельному компоненту продовольственной системы. Сельское хозяйство должно стать важным элементом смягчения последствий изменения климата и адаптивных стратегий. Автор утверждает, что Россия является перспективным кандидатом среди бореальных регионов, способным воспользоваться сложившейся ситуацией и превратиться из импортера сельскохозяйственной продукции в солидного мирового экспортера продовольствия. В статье представлено несколько факторов, которые могут стать основой новой агропродовольственной стратегии России. Но чтобы в полной мере воспользоваться такими возможностями, необходимы существенные преобразования. Подводя итоги некоторых изменений в аграрном секторе, автор дает рекомендации, которые могли бы повысить роль Российской Федерации на агропродовольственных мировых рынках
Radiation reaction and quantum damped harmonic oscillator
By taking a Klein-Gordon field as the environment of an harmonic oscillator
and using a new method for dealing with quantum dissipative systems (minimal
coupling method), the quantum dynamics and radiation reaction for a quantum
damped harmonic oscillator investigated. Applying perturbation method, some
transition probabilities indicating the way energy flows between oscillator,
reservoir and quantum vacuum, obtainedComment: 12 pages. Accepted for publication in Mod. Phys. Lett.
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
Geometrical view of quantum entanglement
Although a precise description of microscopic physical problems requires a
full quantum mechanical treatment, physical quantities are generally discussed
in terms of classical variables. One exception is quantum entanglement which
apparently has no classical counterpart. We demonstrate here how quantum
entanglement may be within the de Broglie-Bohm interpretation of quantum
mechanics visualized in geometrical terms, giving new insight into this
mysterious phenomenon and a language to describe it. On the basis of our
analysis of the dynamics of a pair of qubits, quantum entanglement is linked to
concurrent motion of angular momenta in the Bohmian space of hidden variables
and to the average angle between these momenta
Neural network based prediction of roughing and finishing times in a hot strip mill
The paper presents a model based on neural networks which is able to predict the time required to pass the different gauges of a roughing and finishing mill as function of some slab features and process parameters. The final aim of the work is to increase the rolling efficiency while avoiding collisions and queues that cause time and energy losses. Neural networks are suitable to this prediction task as they are particularly able to cope with unknown non linear relationships between input and output variables. Moreover they can learn from real industrial data and therefore do not require prior assumptions or mathematical modelling of the process and transferability is ensured by the possibility to use different databases coming from different rolling mills. In the paper, two different kinds of neural network- based models have been proposed, their performances have been discussed and compared.En este artículo se presenta un modelo basado en redes neuronales capaz de predecir el tiempo necesario para pasar las diferentes galgas de un tren desbastador y acabador en función de ciertas características del desbaste y parámetros de proceso. El objetivo final es aumentar la eficacia de la laminación evitando colisiones y colas que provoquen pérdidas de tiempo y energía. Se propone utilizar para esta tarea redes neuronales por su capacidad de predicción en aquellos casos en los que existen relaciones no lineales desconocidas entre las variables de entrada y las de salida. Además, son capaces de aprender de datos industriales reales y, por tanto, no requieren suposiciones previas o modelos matemáticos del proceso, estando la transferibilidad asegurada ya que es posible utilizar distintas bases de datos procedentes de diferentes trenes de laminación
The antiquity of hydrocephalus: the first full palaeo-neuropathological description
The Pathology Museum of the University of Florence houses a rich collection of anatomical specimens and over a hundred waxworks portraying pathological conditions occurring in the nineteenth century, when the museum was established. Clinical and autopsy findings of these cases can still be retrieved from the original museum catalogue, offering a rare opportunity for retrospective palaeo-pathological diagnostics. We present a historical case of severe hydrocephalus backed by modern-day anthropological, radiological and molecular analyses conducted on the skeleton of an 18-month-old male infant deceased in 1831. Luigi Calamai (1796-1851), a wax craftsman of La Specola workshop in Florence, was commissioned to create a life-sized wax model of the child's head, neck and upper thorax. This artwork allows us to appreciate the cranial and facial alterations determined by 30 lb of cerebrospinal fluid (CSF) accumulated within the cerebral ventricular system. Based on the autopsy report, gross malformations of the neural tube, tumours and haemorrhage could be excluded. A molecular approach proved helpful in confirming sex. We present this case as the so-far most compelling case of hydrocephalus in palaeo-pathological research
Comparison of selection methods for the establishment of a core collection using SSR markers for hazelnut (Corylus avellana L.) accessions from European germplasm repositories
- …