244 research outputs found
Uncertainty relations for the support of quantum states
Given a narrow signal over the real line, there is a limit to the
localisation of its Fourier transform. In spaces of prime dimensions, Tao
derived a sharp state-independent uncertainty relation which holds for the
support sizes of a pure qudit state in two bases related by a discrete Fourier
transform. We generalise Tao's uncertainty relation to complete sets of
mutually unbiased bases in spaces of prime dimensions. The bound we obtain
appears to be sharp for dimension three only. Analytic and numerical results
for prime dimensions up to nineteen suggest that the bound cannot be saturated
in general. For prime dimensions two to seven we construct sharp bounds on the
support sizes in mutually unbiased bases and identify some of the
states achieving them
The effects of privatization and consolidation on bank productivity: comparative evidence from Italy and Germany
The Italian and German banking systems shared similar characteristics early in the 1990s but have evolved in different directions since then: Italy privatized its publicly-owned banks while Germany has maintained a large share of state-owned savings banks. Contemporaneously, banks in both markets engaged heavily in mergers and acquisitions. We analyze how these activities have affected banks' productivity in the period 1994-2004, differentiating between technical change, efficiency change and scale economies. We find that privatized banks experienced a significant increase in productivity, especially if they subsequently merged with other banks. German banks were still able to increase their productivity through consolidation. --Banking market integration,deregulation,total factor productivity,Italy,Germany
The effects of privatization and consolidation on bank productivity: comparative evidence from Italy and Germany
The Italian and German banking systems shared similar characteristics early in the 1990s but have evolved in different directions since then: Italy privatized its publicly-owned banks while Germany has maintained a large share of state-owned savings banks. Contemporaneously, banks in both markets engaged heavily in mergers and acquisitions. We analyze how these activities have affected banksÂ’ productivity in the period 1994-2004, differentiating between technical change, efficiency change and scale economies. We find that privatized banks experienced a significant increase in productivity, especially if they subsequently merged with other banks. German banks were still able to increase their productivity through consolidation.banking market integration, deregulation, total factor productivity, Italy, Germany
Uncertainty relations for the support of quantum states
Given a narrow signal over the real line, there is a limit to the localisation of its Fourier transform. In spaces of prime dimensions, Tao derived a sharp state-independent uncertainty relation which holds for the support sizes of a pure qudit state in two bases related by a discrete Fourier transform. We generalise Tao's uncertainty relation to complete sets of mutually unbiased bases in spaces of prime dimensions. The bound we obtain appears to be sharp for dimension three only. Analytic and numerical results for prime dimensions up to nineteen suggest that the bound cannot be saturated in general. For prime dimensions two to seven we construct sharp bounds on the support sizes in (d + 1) mutually unbiased bases and identify some of the states achieving them
Power-efficient distributed resource allocation under goodput QoS constraints for heterogeneous networks
This work proposes a distributed resource allocation (RA) algorithm for packet bit-interleaved coded OFDM transmissions in the uplink of heterogeneous networks (HetNets), characterized by small cells deployed over a macrocell area and sharing the same band. Every user allocates its transmission resources, i.e., bits per active subcarrier, coding rate, and power per subcarrier, to minimize the power consumption while both guaranteeing a target quality of service (QoS) and accounting for the interference inflicted by other users transmitting over the same band. The QoS consists of the number of information bits delivered in error-free packets per unit of time, or goodput (GP), estimated at the transmitter by resorting to an efficient effective SNR mapping technique. First, the RA problem is solved in the point-to-point case, thus deriving an approximate yet accurate closed-form expression for the power allocation (PA). Then, the interference-limited HetNet case is examined, where the RA problem is described as a non-cooperative game, providing a solution in terms of generalized Nash equilibrium. Thanks to the closed-form of the PA, the solution analysis is based on the best response concept. Hence, sufficient conditions for existence and uniqueness of the solution are analytically derived, along with a distributed algorithm capable of reaching the game equilibrium
A Quantum Theory with Non-collapsing Measurements
A collapse-free version of quantum theory is introduced to study the role of the projection postulate. We assume "passive" measurements that do not update quantum states while measurement outcomes still occur probabilistically, in accordance with Born's rule. All other defining features of quantum theory, such as the Hilbert space setting, are retained. The resulting quantum-like theory has only one type of dynamics, namely unitary evolution. Passive quantum theory shares many features with standard quantum theory. These include preparational uncertainty relations, the impossibility to dynamically clone unknown quantum states and the absence of signalling. However, striking differences emerge when protocols involve post-measurement states. For example, in the collapse-free setting, no ensemble is needed to reconstruct the state of a system by passively measuring a tomographically complete set of observables - a single system will do. Effectively, the state becomes an observable quantity, with implications for both the ontology of the theory and its computational power. At the same time, the theory is not locally tomographic and passive measurements do not create Bell-type correlations in composite systems
A robust resource allocation algorithm for packet BIC-UFMC 5G wireless communications
In this paper, we present a novel resource allocation (RA) algorithm for packet Universal Filtered Multi-Carrier (UFMC) BIC-based communications, the latter being a novel modulation format possibly envisaged to be applied in 5G wireless systems. Assuming the perfect knowledge of the channel and capitalizing on the specific UFMC signal waveform, the proposed RA strategy optimizes the coding rate and bit loading within the overall bandwidth along with the per-subband power distribution. In the presence of a carrier offset and over fading selective channels, the results we obtained are twofold: i) the UFMC format reveals to be more robust than the conventional OFDM scheme; ii) the performance of the UFMC system itself is further boosted by the optimal choice of radio resources evaluated by the proposed RA algorithm
On the use of asymmetric PSF on NIR images of crowded stellar fields
We present data collected using the camera PISCES coupled with the Firt Light
Adaptive Optics (FLAO) mounted at the Large Binocular Telescope (LBT). The
images were collected using two natural guide stars with an apparent magnitude
of R<13 mag. During these observations the seeing was on average ~0.9". The AO
performed very well: the images display a mean FWHM of 0.05 arcsec and of 0.06
arcsec in the J- and in the Ks-band, respectively. The Strehl ratio on the
quoted images reaches 13-30% (J) and 50-65% (Ks), in the off and in the central
pointings respectively. On the basis of this sample we have reached a J-band
limiting magnitude of ~22.5 mag and the deepest Ks-band limiting magnitude ever
obtained in a crowded stellar field: Ks~23 mag.
J-band images display a complex change in the shape of the PSF when moving at
larger radial distances from the natural guide star. In particular, the stellar
images become more elongated in approaching the corners of the J-band images
whereas the Ks-band images are more uniform. We discuss in detail the strategy
used to perform accurate and deep photometry in these very challenging images.
In particular we will focus our attention on the use of an updated version of
ROMAFOT based on asymmetric and analytical Point Spread Functions.
The quality of the photometry allowed us to properly identify a feature that
clearly shows up in NIR bands: the main sequence knee (MSK). The MSK is
independent of the evolutionary age, therefore the difference in magnitude with
the canonical clock to constrain the cluster age, the main sequence turn off
(MSTO), provides an estimate of the absolute age of the cluster. The key
advantage of this new approach is that the error decreases by a factor of two
when compared with the classical one. Combining ground-based Ks with space
F606W photometry, we estimate the absolute age of M15 to be 13.70+-0.80 Gyr.Comment: 15 pages, 7 figures, presented at the SPIE conference 201
New technologies sustainability: monitoring and evaluation of results of interventions for the promotion of cultural heritage and the human landscape
The relationship between the development of technologies and the history of the cultural and agricultural landscape is linked to the concepts of "cultural landscape", understood as a space in continuous construction that changes with the change of individual, collective, social and cultural relationships of the inhabitants of the territory, or of the "cultural inhabitants", citizens who are producers of culture, rather than users. A vision of the "future as an open place" emerges, understood as a place of usability and sharing of all human, material and immaterial productions.Technologies, within a similar perspective, are presented as the historical evolution of téchne, whose degree of development today allows an extension of the level of human action.This study, in agreement with the scientific literature based on the use of recently developed digital models, demonstrates that the mainly agricultural territory of Basilicata, historically the site of complex social relations, has created a traditional rural society in which the concept of neighborhood and the spatial connotation also had the symbolic value of sharing knowledge and practices, relationships based on inclusiveness and sustainability. The diffusion of 5G technology is generating important cultural transformations. What used to be the neighborhood community in Matera (IT) - also following the activities launched with the CTEMT project and the social consequences of the Covid-19 pandemic - is now becoming a virtual community for sharing knowledge and practices , beliefs and values, including the use and management of cultural heritage, which takes place through the network, and therefore using applications that promote a transformative intervention of the landscape, such as to make it functional to human needs, and, at the same time, sustainable with respect to the perpetuation of ecosystem relationships.The diffusion of 5G technology, is generating important cultural transformations. What in the past was, in Matera (IT), the neighbourhood community - also as a result of the activities launched with the CTEMT project and the social consequences of the Covid-19 pandemic - now becomes a virtual community, sharing knowledge and practices, beliefs and values, including the use and management of cultural heritage, occurs through the network with the use of applications that promote accessibility and sustainability in both the urban and agricultural landscape. As argued by the International Union for Conservation of Nature (IUCN), the attention to the dynamic conservation of the landscape should not be placed so much to the "culture itself" or to the "nature itself" but rather to the relationship between these two dynamic components has been established, but also from the holistic mentioned many times, attentive to the values of identity and comforted by the knowledge and decoding of the intangible heritage, from which we deduce the active role, shared social behaviours, the mechanisms of transmission of knowledge and transgenerational awareness also thanks to the complex and fascinating universe of uses, traditions, rituals and rites that are an important tool of conscious management of the landscape and its culture. The conscious use of artificial intelligence is the concretion of the virtuous relationship between Humanism and technologies. For the biodiversity it is a support to the recognition of the species, in particular of the native ones, and it allows people to recognize themselves culturally and find into the biodiversity a collective and cultural belonging to the community and to the landscape. Therefore, thanks to the use of new technologies biodiversity becomes an historical-anthropological archive of knowledge and practices of a territory, and new technologies a powerful tool for the conservation of the cultural heritage
Are ancient dwarf satellites the building blocks of the Galactic halo?
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. ©: 2016 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.According to the current cosmological cold dark matter paradigm, the Galactic halo could have been the result of the assemblage of smaller structures. Here we explore the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the Milky Way have been the building blocks of the Galactic halo by comparing their [α/Fe] and [Ba/Fe] versus [Fe/H] patterns with the ones observed in Galactic halo stars. The α elements deviate substantially from the observed abundances in the Galactic halo stars for [Fe/H] values larger than −2 dex, while they overlap for lower metallicities. On the other hand, for the [Ba/Fe] ratio, the discrepancy is extended at all [Fe/H] values, suggesting that the majority of stars in the halo are likely to have been formed in situ. Therefore, we suggest that [Ba/Fe] ratios are a better diagnostic than [α/Fe] ratios. Moreover, for the first time we consider the effects of an enriched infall of gas with the same chemical abundances as the matter ejected and/or stripped from dwarf satellites of the Milky Way on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the assumed infall time-scale, and the presence of a threshold in the gas for star formation. In particular, in models with an infall time-scale for the halo around 0.8 Gyr coupled with a threshold in the surface gas density for the star formation (4 M pc−2), and the enriched infall from dwarf spheroidal satellites, the first halo stars formed show [Fe/H]>−2.4 dex. In this case, to explain [α/Fe] data for stars with [Fe/H]<−2.4 dex, we need stars formed in dSph systems.Peer reviewedFinal Published versio
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