17,419 research outputs found
Universal Lossless Compression with Unknown Alphabets - The Average Case
Universal compression of patterns of sequences generated by independently
identically distributed (i.i.d.) sources with unknown, possibly large,
alphabets is investigated. A pattern is a sequence of indices that contains all
consecutive indices in increasing order of first occurrence. If the alphabet of
a source that generated a sequence is unknown, the inevitable cost of coding
the unknown alphabet symbols can be exploited to create the pattern of the
sequence. This pattern can in turn be compressed by itself. It is shown that if
the alphabet size is essentially small, then the average minimax and
maximin redundancies as well as the redundancy of every code for almost every
source, when compressing a pattern, consist of at least 0.5 log(n/k^3) bits per
each unknown probability parameter, and if all alphabet letters are likely to
occur, there exist codes whose redundancy is at most 0.5 log(n/k^2) bits per
each unknown probability parameter, where n is the length of the data
sequences. Otherwise, if the alphabet is large, these redundancies are
essentially at least O(n^{-2/3}) bits per symbol, and there exist codes that
achieve redundancy of essentially O(n^{-1/2}) bits per symbol. Two sub-optimal
low-complexity sequential algorithms for compression of patterns are presented
and their description lengths analyzed, also pointing out that the pattern
average universal description length can decrease below the underlying i.i.d.\
entropy for large enough alphabets.Comment: Revised for IEEE Transactions on Information Theor
Neutrino Physics
The fundamental properties of neutrinos are reviewed in these lectures. The
first part is focused on the basic characteristics of neutrinos in the Standard
Model and how neutrinos are detected. Neutrino masses and oscillations are
introduced and a summary of the most important experimental results on neutrino
oscillations to date is provided. Then, present and future experimental
proposals are discussed, including new precision reactor and accelerator
experiments. Finally, different approaches for measuring the neutrino mass and
the nature (Majorana or Dirac) of neutrinos are reviewed. The detection of
neutrinos from supernovae explosions and the information that this measurement
can provide are also summarized at the end.Comment: 50 pages, contribution to the 2011 CERN-Latin-American School of
High-Energy Physics, Natal, Brazil, 23 March-5 April 2011, edited by C.
Grojean, M. Mulders and M. Spiropulu. arXiv admin note: text overlap with
arXiv:1010.5112, arXiv:1010.4131, arXiv:0704.1800 by other author
Oscillation parameters present: Session summary
© Copyright owned by the author(s) under the terms of the Creative Commons. Session I of the Neutrino Oscillation Workshop 2018 Conference, “Neutrino Oscillations: Present”, is summarised. Results were presented by the currently-running long-baseline oscillation experiments T2K and NOvA, as well as from the accelerator experiments OPERA and MiniBooNE. Status reports and results from experiments using short-baseline accelerator neutrinos (ICARUS and MicroBooNE), atmospheric neutrinos (Super-K, IceCube and ANTARES), and those from reactors (Daya Bay and Double Chooz), and from the Sun and the Earth (Borexino) were also presented. Our current knowledge of neutrino oscillation parameters depends significantly on the experimental inputs that inform us of details of the production and interactions of neutrinos, which were presented by the NA61/SHINE hadron production experiment and cross section measurements from T2K and MINERvA, as well as a review of the status of our understanding of neutrino production at nuclear reactors. The session also included theoretical reviews of the current status of neutrino oscillations, and phenomenological studies on neutrino tomography and experimental studies to support nuclear matrix element calculations (NUMEN)
Benefits of Older Volunteering on Wellbeing: An International Comparison
Healthier aging implies lower health service expenditure and the possibility for individuals to make a longer and more valuable contribution to society. Lifestyles, including volunteering, affect our health. The policy implications of the present study are that it aims to broaden the state of knowledge and be useful to public decision-makers: if voluntary activities enhance the integration of older people into society, their participation will help to generate economic resources and improve their own welfare; if, however, health and participation do not show positive synergies, then policymakers must act independently in each of these fields. In this work, we focus on the societies of Chile, Mexico, and Spain because they have significantly aging populations and share common traits but also exhibit important differences. The empirical study employs micro-data from the World Value Survey (1994–1998, 2005–2009, and 2010–2014) and macro-data from the statistics of the OECD (Organization for Economic Co-operation and Development). Micro- and macro-data are merged by national and temporal identifiers. Our main results provide empirical evidence that volunteering might improve every indicator of wellbeing except happiness. Different kinds of activities have different impacts on individual wellbeing. For example, volunteering in activities related to social awareness is positive for male life satisfaction, whereas volunteering in activities related to religious issues is positive for male life satisfaction but also female happiness. In general, voluntary activities have a stronger impact on male wellbeing than female wellbeing
Verdaguer a Folgueroles: un recurs local ben aprofitat. Estudi d'un sistema local territorial
Non-equilibrium physics of Rydberg lattices in the presence of noise and dissipative processes
We study the non-equilibrium dynamics of driven spin lattices in the presence
of decoherence caused by either laser phase noise or strong decay. In the first
case, we discriminate between correlated and uncorrelated noise and explore
their effect on the mean density of Rydberg states and the full counting
statistics (FCS). We find that while the mean density is almost identical in
both cases, the FCS differ considerably. The main method employed is the
Langevin equation (LE) but for the sake of efficiency in certain regimes, we
use a Markovian master equation and Monte Carlo rate equations, respectively.
In the second case, we consider dissipative systems with more general power-law
interactions. We determine the phase diagram in the steady state and analyse
its generation dynamics using Monte Carlo rate equations. In contrast to
nearest-neighbour models, there is no transition to long-range-ordered phases
for realistic interactions and resonant driving. Yet, for finite laser
detunings, we show that Rydberg lattices can undergo a dissipative phase
transition to a long-range-ordered antiferromagnetic (AF) phase. We identify
the advantages of Monte Carlo rate equations over mean field (MF) predictions
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