14,541 research outputs found
Performance of two branch space and polarization diversity at 900 MHz
This work summarizes the results of a measurement campaign undertaken to evaluate the performance of two branch space and polarization diversity schemes at 900 MHz in different environments (urban, suburban, rural flat and rural hilly). A total number of 783 runs were made covering these sites and using different transmitter antennas (vertical polarized roof-top antenna, handheld randomly inclined) at differents speeds (walking, by car at 30 up to 80 km/h). Comparison between the two types of diversity schemes have been made through calculation of the statistics of mean received signal level, diversity gain, incremental diversity gain and envelope cross-correlationPeer ReviewedPostprint (published version
Functional advantages offered by many-body coherences in biochemical systems
Quantum coherence phenomena driven by electronic-vibrational (vibronic)
interactions, are being reported in many pulse (e.g. laser) driven chemical and
biophysical systems. But what systems-level advantage(s) do such many-body
coherences offer to future technologies? We address this question for pulsed
systems of general size N, akin to the LHCII aggregates found in green plants.
We show that external pulses generate vibronic states containing particular
multipartite entanglements, and that such collective vibronic states increase
the excitonic transfer efficiency. The strength of these many-body coherences
and their robustness to decoherence, increase with aggregate size N and do not
require strong electronic-vibrational coupling. The implications for energy and
information transport are discussed.Comment: arXiv admin note: text overlap with arXiv:1706.0776
Pulsed Generation of Quantum Coherences and Non-classicality in Light-Matter Systems
We show that a pulsed stimulus can be used to generate many-body quantum
coherences in light-matter systems of general size. Specifically, we calculate
the exact real-time evolution of a driven, generic out-of-equilibrium system
comprising an arbitrary number N qubits coupled to a global boson field. A
novel form of dynamically-driven quantum coherence emerges for general N and
without having to access the empirically challenging strong-coupling regime.
Its properties depend on the speed of the changes in the stimulus.
Non-classicalities arise within each subsystem that have eluded previous
analyses. Our findings show robustness to losses and noise, and have potential
functional implications at the systems level for a variety of nanosystems,
including collections of N atoms, molecules, spins, or superconducting qubits
in cavities -- and possibly even vibration-enhanced light harvesting processes
in macromolecules.Comment: 9 pages, 4 figure
Optimizing Scan Homogeneity for Building Full-3D Lidars based on Rotating a Multi-Beam Velodyne Rangefinder
Multi-beam lidar (MBL) scanners are compact, light, and accessible 3D sensors with high data rates, but they offer limited vertical resolution and field of view (FOV).
Some recent robotics research has profited from the addition of a degree-of-freedom (DOF) to an MBL to build rotating multi-beam lidars (RMBL) that can achieve high-resolution scans with full spherical FOV. In a previous work, we offered a methodology to analyze the complex 3D scan measurement distributions produced by RMBLs with a rolling DOF and no pitching. In this paper, we investigate the effect of introducing constant pitch angles in the construction of the RMBLs with the purpose of finding a kinematic configuration that optimizes scan homogeneity with a spherical FOV. To this end, we propose a scalar index of 3D sensor homogeneity that is based on the spherical formulation of Ripley's K function. The optimization is performed for the widely used Puck (VLP-16) and HDL-32 sensors by Velodyne.This work was partially funded by the Spanish project {DPI2015-65186-R}. The publication has received support from Universidad de Málaga, Campus de Excelencia Andalucía Tech
Faint emission lines in the Galactic H II regions M16, M20 and NGC 3603
We present deep echelle spectrophotometry of the Galactic {\hii} regions M16,
M20 and NGC 3603. The data have been taken with the Very Large Telescope
Ultraviolet-Visual Echelle Spectrograph in the 3100 to 10400 \AA range. We have
detected more than 200 emission lines in each region. Physical conditions have
been derived using different continuum and line intensity ratios. We have
derived He, C and O abundances from pure recombination
lines as well as abundances from collisionally excited lines for a large number
of ions of different elements. We have obtained consistent estimations of the
temperature fluctuation parameter, {\ts}, using different methods. We also
report the detection of deuterium Balmer lines up to D (M16) and to
D (M20) in the blue wings of the hydrogen lines, which excitation
mechanism seems to be continuum fluorescence. The temperature fluctuations
paradigm agree with the results obtained from optical CELs and the more
uncertain ones from far IR fine structure CELs in NGC 3603, although, more
observations covering the same volume of the nebula are necessary to obtain
solid conclusions.Comment: 22 pages, 13 Tables, 7 Figures. Accepted for publication by MNRA
The moderating role of gender on entrepreneurial intentions: a TPB perspective
Purpose: To disentangle the ways in which social norms shape entrepreneurial intentions of university students and to analyse the moderating effect of gender that may arise.
Design/methodology/approach: We have used the entrepreneurial intention model based on Theory of Planned Behaviour (TPB) literature and moderated by students’ gender affecting this intention. We tested some hypotheses using data from undergraduate business students in Spain and their entrepreneurial intentions.
Findings: Our results suggest that perceived behavioural control and attitudes affect the entrepreneurial intentions of university students towards entrepreneurship while subjective norms do not. Furthermore, our findings reveal that the moderating effect of gender has a positive influence for women in the relationship between those subjective norms and the perceived behavioural control. However, as to some research done so far, the moderating role of gender does not seem to have a particular effect on predicting entrepreneurial intentions when moderating TPB dimensions.
Practical implications: Given the socio-economic benefits attributed to entrepreneurship, the results allow the design of more effective education initiatives and policies.
Originality/value: This research provides support for the application of the TPB, allowing for a better understanding of gender differences in entrepreneurial intentions
The digital transformation of work: a relational view
Conversation about the current and potential effects of digital technologies on the nature of work is raging within scholarly and practitioner communities. Artificial intelligence, robotics, data analytics, digital platforms, and automation, among other technologies, are prompting a swift and profound transformation of work. Building on Pierpaolo Donati''s relational sociology, we examine the changes these technologies are likely to bring about in work as a human relation. Despite the very real threats of unemployment, job insecurity, precariousness, and surveillance, technology may also encourage the emergence of a work culture that shifts the scales toward a relational realm rather than a transactional one. To this end, we argue that work should be understood as a social relation with four dimensions: exchange value, intrinsic extra-economic purpose, communication for reciprocal services, and correspondence with primary human needs according to use values. Understanding the digital transformation of work from this point of view requires comprehending the differentiation and integration of these four dimensions
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