1,194 research outputs found
When Things Matter: A Data-Centric View of the Internet of Things
With the recent advances in radio-frequency identification (RFID), low-cost
wireless sensor devices, and Web technologies, the Internet of Things (IoT)
approach has gained momentum in connecting everyday objects to the Internet and
facilitating machine-to-human and machine-to-machine communication with the
physical world. While IoT offers the capability to connect and integrate both
digital and physical entities, enabling a whole new class of applications and
services, several significant challenges need to be addressed before these
applications and services can be fully realized. A fundamental challenge
centers around managing IoT data, typically produced in dynamic and volatile
environments, which is not only extremely large in scale and volume, but also
noisy, and continuous. This article surveys the main techniques and
state-of-the-art research efforts in IoT from data-centric perspectives,
including data stream processing, data storage models, complex event
processing, and searching in IoT. Open research issues for IoT data management
are also discussed
EG-Sozialpolitik nach Verflechtungsfalle und EntscheidungslĂŒcke: BewertungsmaĂstĂ€be und Entwicklungstrends
Bis in die 1990er Jahre befand sich die EG-Sozialpolitik infolge weitestgehender Einstimmigkeitserfordernisse in einer âPolitikverflechtungsfalleâ (Fritz W. Scharpf), die noch durch eine, korporatistische EntscheidungslĂŒckeâ (Wolfgang Streeck) ergĂ€nzt wurde. Der Maastrichter Vertrag brachte allerdings signifikante Neuerungen in Hinblick auf Handlungskompetenzen, Mehrheitsvoten und die korporatistische Einbeziehung der SozialpartnerverbĂ€nde. Dass diese Potenziale entgegen vielfachen Erwartungen auch praktisch zur Anwendung kamen, heiĂt allerdings noch nicht, dass die ProblemlösungskapazitĂ€t der EG-Sozialpolitik schon zufrieden stellend wĂ€re. Dieser Beitrag analysiert unterschiedliche BeurteilungsmaĂstĂ€be dafĂŒr und zeigt auf, dass die âsoziale Dimensionâ bei Anwendung von inhaltlich vergleichsweise eng definierten AnsprĂŒchen mittlerweile besser abschneidet, als oft erwartet wurde (SchlieĂung akuter arbeitsrechtlicher LĂŒcken; KommissionsvorschlĂ€ge im Vergleich zu RatsbeschlĂŒssen). Noch tut die Union allerdings wenig, um marktinduziertem Druck auf soziale Standards in den Mitgliedstaaten entgegenzuwirken. Bislang kaum ernsthaft diskutiert wurde auch die NĂŒtzung jener Potenziale fĂŒr sozialgestaltende Politik auf supranationaler Ebene, die heute angesichts offener MĂ€rkte in den Mitgliedstaaten immer weniger bestehen. Als Entwicklungstrend zeichnet sich in allerjĂŒngster Zeit eine völlig neue Rolle fĂŒr die EG-Sozialpolitik im 21. Jahrhundert ab: als Motor und zugleich Korsett fĂŒr auf nationaler Ebene entschiedene Reformen.Until the 1990s, eC social policy was characterised by a joint-decision trap (Fritz W. Scharpf) characterized by a joint decision trap and a concomitant âcorporatist decision gapâ (Wolfgang Streeck). The Maastricht Treaty, however, brought significant innovation in terms of EC competencies, majority voting, and corporatist decision patterns. The fact that some of these potential improvements have actually been put into practice â surprisingly for many â does not, however, mean that the problem solving capacity of the EC in social policy is satisfying. This article analyses several quite different yardsticks and shows that the âsocial dimensionâ is more successful than was often expected, in the light of the less ambitious standards (closing labour law gaps induced by the Internal Market; Commission proposals compared to Council decisions). By contrast, the EC does little to fight devaluative pressures on the national social standards, and it does not yet make use of the specific potential for improvements in social policy which nowadays tends to exist on the supranational level rather than on the national one. Very recently, however, there has been a trend towards a new role for EC social policy in the 21st century: as a catalyst and, at the same time, corset for reforms decided upon at the national level
Edge Influence Computation in Dynamic Graphs
Reachability queries are of great importance in many research and application areas, including general graph mining, social network analysis and so on. Many approaches have been proposed to compute whether there exists one path from one node to another node in a graph. Most of these approaches focus on static graphs, however in practice dynamic graphs are more common. In this paper, we focus on handling graph reachability queries in dynamic graphs. Specifically we investigate the influence of a given edge in the graph, aiming to study the overall reachability changes in the graph brought by the possible failure/deletion of the edge. To this end, we firstly develop an efficient update algorithm for handling edge deletions. We then define the edge influence concept and put forward a novel computation algorithm to accelerate the computation of edge influence. We evaluate our approach using several real world datasets. The experimental results show that our approach outperforms traditional approaches significantly
Formation of phase lags at the cyclotron energies in the pulse profiles of magnetized, accreting neutron stars
Context: Accretion-powered X-ray pulsars show highly energy-dependent and
complex pulse-profile morphologies. Significant deviations from the average
pulse profile can appear, in particular close to the cyclotron line energies.
These deviations can be described as energy-dependent phase lags, that is, as
energy-dependent shifts of main features in the pulse profile. Aims: Using a
numerical study we explore the effect of cyclotron resonant scattering on
observable, energy-resolved pulse profiles. Methods: We generated the
observable emission as a function of spin phase, using Monte Carlo simulations
for cyclotron resonant scattering and a numerical ray-tracing routine
accounting for general relativistic light-bending effects on the intrinsic
emission from the accretion columns. Results: We find strong changes in the
pulse profile coincident with the cyclotron line energies. Features in the
pulse profile vary strongly with respect to the average pulse profile with the
observing geometry and shift and smear out in energy additionally when assuming
a non-static plasma. Conclusions: We demonstrate how phase lags at the
cyclotron energies arise as a consequence of the effects of angular
redistribution of X-rays by cyclotron resonance scattering in a strong magnetic
field combined with relativistic effects. We also show that phase lags are
strongly dependent on the accretion geometry. These intrinsic effects will in
principle allow us to constrain a system's accretion geometry.Comment: 4 pages, 4 figures; updated reference lis
Cyclotron resonant scattering feature simulations. I. Thermally averaged cyclotron scattering cross sections, mean free photon-path tables, and electron momentum sampling
Electron cyclotron resonant scattering features (CRSFs) are observed as
absorption-like lines in the spectra of X-ray pulsars. A significant fraction
of the computing time for Monte Carlo simulations of these quantum mechanical
features is spent on the calculation of the mean free path for each individual
photon before scattering, since it involves a complex numerical integration
over the scattering cross section and the (thermal) velocity distribution of
the scattering electrons.
We aim to numerically calculate interpolation tables which can be used in
CRSF simulations to sample the mean free path of the scattering photon and the
momentum of the scattering electron. The tables also contain all the
information required for sampling the scattering electron's final spin.
The tables were calculated using an adaptive Simpson integration scheme. The
energy and angle grids were refined until a prescribed accuracy is reached. The
tables are used by our simulation code to produce artificial CRSF spectra. The
electron momenta sampled during these simulations were analyzed and justified
using theoretically determined boundaries.
We present a complete set of tables suited for mean free path calculations of
Monte Carlo simulations of the cyclotron scattering process for conditions
expected in typical X-ray pulsar accretion columns (0.01<B/B_{crit}<=0.12,
where B_{crit}=4.413x10^{13} G and 3keV<=kT<15keV). The sampling of the tables
is chosen such that the results have an estimated relative error of at most
1/15 for all points in the grid. The tables are available online at
http://www.sternwarte.uni-erlangen.de/research/cyclo.Comment: A&A, in pres
Localization, analysis and evolution of transposed human immunoglobulin VK genes
The localization of VÎș gene regions to chromosome 2, on which the Îș locus is located, and to other chromosomes is described. The VÎș genes that have been transposed to other chromosomes are called orphons. The finding of two new VÎș genes on chromosome 22 is reported. A VÎș II gene of this region and two VÎș I genes of the Chr 1 and the cos 118 regions were sequenced. The two VÎș I orphon sequences and two others that had been determined previously were 97.5% identical, indicating that they may have evolved from a common ancestor by amplification. A model of the evolution of the human VÎș orphons is discussed.
Author Keywords: Human-rodent cell hybrids; cosmids; restriction maps; ligation artifacts; orphon; recombinant DNA
Abbreviations: aa, amino acid(s); bp, base pair(s); Chr1, VÎș gene-containing regions of chromosomes 1; Chr22, VÎș gene-containing regions of chromosomes 22; FR, framework regions; CDR, complementary determining regions; kb, kilo-base(s) or 1000 bp; L, LâČ, parts of a leader gene segment; m219-1, the first subclone of the cosmid clone cos 219; orphon, VÎș gene outside the Îș locus on chromosome 2pl2; SSC, 0.15 M NaCl, 0.015 M Na3-citrate, pH 7.6; V, variable gene segments; J, joining gene segments; C, constant gene segments; VÎș I to VÎș IV, variable gene segments of immunoglobulin light chains of the Îș type belonging to subgroups I to IV; for reasons of simplicity VÎș gene segments are generally called VÎș gene
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