1,073 research outputs found
An explicit height bound for the classical modular polynomial
For a prime m, let Phi_m be the classical modular polynomial, and let
h(Phi_m) denote its logarithmic height. By specializing a theorem of Cohen, we
prove that h(Phi_m) <= 6 m log m + 16 m + 14 sqrt m log m. As a corollary, we
find that h(Phi_m) <= 6 m log m + 18 m also holds. A table of h(Phi_m) values
is provided for m <= 3607.Comment: Minor correction to the constants in Theorem 1 and Corollary 9. To
appear in the Ramanujan Journal. 17 pages
Spatially embedded random networks
Many real-world networks analyzed in modern network theory have a natural spatial element; e.g., the Internet, social networks, neural networks, etc. Yet, aside from a comparatively small number of somewhat specialized and domain-specific studies, the spatial element is mostly ignored and, in particular, its relation to network structure disregarded. In this paper we introduce a model framework to analyze the mediation of network structure by spatial embedding; specifically, we model connectivity as dependent on the distance between network nodes. Our spatially embedded random networks construction is not primarily intended as an accurate model of any specific class of real-world networks, but rather to gain intuition for the effects of spatial embedding on network structure; nevertheless we are able to demonstrate, in a quite general setting, some constraints of spatial embedding on connectivity such as the effects of spatial symmetry, conditions for scale free degree distributions and the existence of small-world spatial networks. We also derive some standard structural statistics for spatially embedded networks and illustrate the application of our model framework with concrete examples
Participatory design, beyond the local
This workshop aims at stimulating and opening a debate around the capacity of Participatory Design (PD) and other co-design approaches to deliver outcomes and methodologies that can have an impact and value for reuse well beyond the local context in which they were originally developed. This will be achieved by stimulating the submission of position papers by researchers from the PD community and beyond.These papers will be discussed during the workshop in order to identify challenges, obstacles but also potentials for scaling up PD processes and results from the local to the global.</p
Comparison between two cases study on water kiosks
Bottled water consumption in Europe began in the 70s. Environmental impact derived from water production chain is very significant: for example plastic bottles use, oil consumption for bottle production, air emission from vehicles transporting bottles, not recycled plastic packages, etc. In this research an environmental and economic impact evaluation was presented for two case studies, regarding water kiosk design with the aim of supplying controlled natural and sparkling water with better organoleptic quality compared to water directly supplied from aqueduct
Entanglement of fields in coupled-cavities: effects of pumping and fluctuations
A system of two coupled cavities is studied in the context of bipartite,
continuous variable entanglement. One of the cavities is pumped by an external
classical source that is coupled quadratically, to the cavity field. Dynamics
of entanglement, quantified by covariance measure [Dodonov {\it et al}, Phys.
Lett A {\bf 296}, (2002) 73], in the presence of cavity-cavity coupling and
external pumping is investigated. The importance of tailoring the coupling
between the cavities is brought out by studying the effects of pump
fluctuations on the entanglement.Comment: 20 pages; 6 figure
Ground states for a class of deterministic spin models with glassy behaviour
We consider the deterministic model with glassy behaviour, recently
introduced by Marinari, Parisi and Ritort, with \ha\ , where is the discrete sine Fourier transform. The
ground state found by these authors for odd and prime is shown to
become asymptotically dege\-ne\-ra\-te when is a product of odd primes,
and to disappear for even. This last result is based on the explicit
construction of a set of eigenvectors for , obtained through its formal
identity with the imaginary part of the propagator of the quantized unit
symplectic matrix over the -torus.Comment: 15 pages, plain LaTe
Application of strategies for particulate matter reduction in urban areas: an italian case
The paper describes the particulate matter pollution in a Northern Italian city: Varese. The city is distinguished by a particular orographic and meteorological situation, characterized by valleys and heavy rainfalls. Nevertheless the urban area is interested by particulate matter pollution mainly due to heating
systems and traffic. Here some corrective strategies in order to reduce PM air pollution have been presented, applied and evaluated by the means of a simplified model which considers emissions and meteorological conditions
UV/TiO2 photocatalytic degradation of xanthene dyes
UV/titanium dioxide (TiO2) degradation of two xanthene
dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a
photocatalytic reactor. Photocatalysis was able to degrade
98% of Ery and 73% of Eos and led to 65% of chemical
oxygen demand removal. Experiments in buffered solutions
at different initial pH values reveal the pH dependence of the
process, with better results obtained under acidic conditions
due to the electrostatic attraction caused by the opposite
charges of TiO2 (positive) and of anionic dyes (negative).
Batch activity tests under methanogenic conditions showed
the high toxicity exerted by the dyes even at low concentrations
(~85% with initial concentration of 0.3 mmol L 1), but
the end products of photocatalytic treatment were much less
toxic toward methanogenic bacteria, as detoxification of
85 ± 5% for Eos and 64 ± 7% for Ery were obtained. In
contrast, the dyes had no inhibitory effect on the biogeniccarbon
biodegradation activity of aerobic biomass, obtained
by respirometry. The results demonstrate that photocatalysis
combining UV/TiO2 as a pretreatment followed by an anaerobic
biological process may be promising for the treatment of
wastewaters produced by many industries.This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS UEFISCDI, project PN-II-ID-PCE-2011-3-0559, contract 265/2011, and the PTDC/AMB/69335/2006 project grants. Luciana Pereira holds a Pos-Doc fellowship (SFRH/BPD/80941/2011), Raquel Pereira holds a fellowship (SFRH/BPD/39086/2007) and Catarina S. Oliveira holds a PhD fellowship (SFRH/BD/32289/2006) from Fundacao para a Ciencia e Tecnologia
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