2,309 research outputs found
On the use of reproducing kernel Hilbert spaces in functional classification
The H\'ajek-Feldman dichotomy establishes that two Gaussian measures are
either mutually absolutely continuous with respect to each other (and hence
there is a Radon-Nikodym density for each measure with respect to the other
one) or mutually singular. Unlike the case of finite dimensional Gaussian
measures, there are non-trivial examples of both situations when dealing with
Gaussian stochastic processes. This paper provides:
(a) Explicit expressions for the optimal (Bayes) rule and the minimal
classification error probability in several relevant problems of supervised
binary classification of mutually absolutely continuous Gaussian processes. The
approach relies on some classical results in the theory of Reproducing Kernel
Hilbert Spaces (RKHS).
(b) An interpretation, in terms of mutual singularity, for the "near perfect
classification" phenomenon described by Delaigle and Hall (2012). We show that
the asymptotically optimal rule proposed by these authors can be identified
with the sequence of optimal rules for an approximating sequence of
classification problems in the absolutely continuous case.
(c) A new model-based method for variable selection in binary classification
problems, which arises in a very natural way from the explicit knowledge of the
RN-derivatives and the underlying RKHS structure. Different classifiers might
be used from the selected variables. In particular, the classical, linear
finite-dimensional Fisher rule turns out to be consistent under some standard
conditions on the underlying functional model
Anderson transition in systems with chiral symmetry
Anderson localization is a universal quantum feature caused by destructive
interference. On the other hand chiral symmetry is a key ingredient in
different problems of theoretical physics: from nonperturbative QCD to highly
doped semiconductors. We investigate the interplay of these two phenomena in
the context of a three-dimensional disordered system. We show that chiral
symmetry induces an Anderson transition (AT) in the region close to the band
center. Typical properties at the AT such as multifractality and critical
statistics are quantitatively affected by this additional symmetry. The origin
of the AT has been traced back to the power-law decay of the eigenstates; this
feature may also be relevant in systems without chiral symmetry.Comment: RevTex4, 4 two-column pages, 3 .eps figures, updated references,
final version as published in Phys. Rev.
Mechanisms for AAA and QoS Interaction
Proceedings of Third IEEE Workshop on Applications and Services in Wireless Networks, ASWN 2003. Bern, Switzerland, July 2-4, 2003.The interaction between Authentication, Authorization and Accounting (AAA) systems and the Quality of Service (QoS) infrastructure is to become a must in the near future. This interaction will allow rich control and management of both users and networks. DIAMETER and DiffServ are likely to turn into the future standards in AAA and QoS systems, but they are not designed to interact with each other. To face this, we propose a new Diameter-Diffserv interaction model and describe the Application Specific Module (ASM) implemented to allow this interaction. The ASM has been implemented and tested in a complete AAA-QoS IPv6 scenario
Multipath propagation model for high altitude platform (HAP) based on circular straigh cone geometry
A geometric model that describes a multipath
propagation for a fixed wireless communication system between a
High Altitude Platform and a fixed terrestrial user is presented.
The model describes the propagation of the reflected signals that
are able to reach the receiver as a consequence of all the
scatterers located inside the system coverage area. The
establishment of a particular geometry characterizing the system
coverage area allows the behavior of the multipath phenomenon
effects to be modeled accurately.Postprint (published version
Differentiable potentials and metallic states in disordered one-dimensional systems
We provide evidence that as a general rule Anderson localization effects
become weaker as the degree of differentiability of the disordered potential
increases. In one dimension a band of metallic states exists provided that the
disordered potential is sufficiently correlated and has some minimum degree of
differentiability. Several examples are studied in detail. In agreement with
the one parameter scaling theory the motion in the metallic region is ballistic
if the spectral density is smooth. Finally, we study the most promising
settings to observe these results in the context of cold atoms.Comment: 5 pages, 3 figures, journal versio
Depth Dependent Relationships between Temperature and Ocean Heterotrophic Prokaryotic Production
9 pĂĄginas, 2 figuras, 1 tabla.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these termsCorrigendum: Depth Dependent Relationships between Temperature and Ocean Heterotrophic Prokaryotic Production, Frontiers in Marine Science 4: 91 (2017) https://doi.org/10.3389/fmars.2017.00091Marine prokaryotes play a key role in cycling of organic matter and nutrients in the ocean. Using a unique dataset (>14,500 samples), we applied a space-for-time substitution analysis to assess the temperature dependence of prokaryotic heterotrophic production (PHP) in epi- (0â200 m), meso- (201â1000 m) and bathypelagic waters (1001â4000 m) of the global ocean. Here, we show that the temperature dependence of PHP is fundamentally different between these major oceanic depth layers, with an estimated ecosystem-level activation energy (Ea) of 36 ± 7 kJ molâ1 for the epipelagic, 72 ± 15 kJ molâ1 for the mesopelagic and 274 ± 65 kJ molâ1 for the bathypelagic realm. We suggest that the increasing temperature dependence with depth is related to the parallel vertical gradient in the proportion of recalcitrant organic compounds. These Ea predict an increased PHP of about 5, 12, and 55% in the epi-, meso-, and bathypelagic ocean, respectively, in response to a water temperature increase by 1°C. Hence, there is indication that a major thus far underestimated feedback mechanism exists between future bathypelagic ocean warming and heterotrophic prokaryotic activityFinancial support for this project was provided by the Australian Institute of Marine Science (AIMS) and a grant from the Carlsberg Foundation to CL. XA, XM and JG were funded by the Malaspina expedition 2010 (grant n° CSD2008â00077) and HOTMIX (grant n° CTM2011â30010âC02â02) projects. TR was supported by the PADOM project (Austrian Science Fund grant n° P23221-B11). GH was funded by the Austrian Science Fund (FWF) project I486-B09 and by the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 268595 (MEDEA project).Peer reviewe
Field evaluation of a 4G âTrue-IPâ network
This article presents field evaluation results of an IP-based architecture for heterogeneous environments, covering UMTS- like TD-CDMA (Time Division-Code Division Multiple Access) wireless access technology, wireless and wired LANs, that has been developed under the aegis of the IST Moby Dick project. The architecture treats all transmission capabilities as basic physical and data-link layers, and attempts to replace all higher-level tasks by IP-based strategies.
The Moby Dick architecture incorporates mobile-IPv6, fast handover, AAA-control (Authentication, Authorization, Accounting), Charging and Quality of Service. The architecture allows for an optimized control on the radio link layer resources. The Moby Dick architecture has been implemented and was evaluated on field trials with multiple services
Assessment of nocturnal aerosol optical depth from lunar photometry at the Izaña high mountain observatory
This work involves a first analysis of the systematic errors observed in the AOD retrieved at nighttime using the Sunâskyâlunar CE318-T photometer. In this respect, this paper is a first attempt to correct the AOD uncertainties that currently affect the lunar photometry by means of an empirical regression model. We have detected and corrected an important bias correlated to the Moon's phase and zenith angles, especially at longer wavelength channels.AERONET Sun photometers at Izaña have been calibrated
within the AERONET Europe TNA, supported by the European
Unionâs Horizon 2020 research and innovation program under
grant agreement no. 654109 (ACTRIS-2)
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