189 research outputs found
Cloudless Friend-to-Friend Middleware for Smartphones
Using smartphones for peer-to-peer communication over the Internet is
difficult without the aid of centralized services. These centralized services,
which usually reside in the cloud, are necessary for brokering communication
between peers, and all communication must pass through them. A reason for this
is that smartphones lack publicly reachable IP addresses. Also, because people
carry their smartphones with them, smartphones will often disconnect from one
network and connect to another. Smartphones can also go offline. Additionally,
a network of trusted peers (or friends) requires a directory of known peers,
authentication mechanisms, and secure communication channels. In this paper, we
propose a peer-to-peer middleware that provides these features without the need
for centralized services.Comment: ICETE 2018: E-Business and Telecommunications pp 199-218. Part of the
Communications in Computer and Information Science book series (CCIS, volume
1118). The final authenticated publication is available online at
https://doi.org/10.1007/978-3-030-34866-3_1
Realism and Objectivism in Quantum Mechanics
The present study attempts to provide a consistent and coherent account of
what the world could be like, given the conceptual framework and results of
contemporary quantum theory. It is suggested that standard quantum mechanics
can, and indeed should, be understood as a realist theory within its domain of
application. It is pointed out, however, that a viable realist interpretation
of quantum theory requires the abandonment or radical revision of the classical
conception of physical reality and its traditional philosophical
presuppositions. It is argued, in this direction, that the conceptualization of
the nature of reality, as arising out of our most basic physical theory, calls
for a kind of contextual realism. Within the domain of quantum mechanics,
knowledge of 'reality in itself', 'the real such as it truly is' independent of
the way it is contextualized, is impossible in principle. In this connection,
the meaning of objectivity in quantum mechanics is analyzed, whilst the
important question concerning the nature of quantum objects is explored.Comment: 20 pages. arXiv admin note: substantial text overlap with
arXiv:0811.3696, arXiv:quant-ph/0502099, arXiv:0904.2702, arXiv:0904.2859,
arXiv:0905.013
Why honey is effective as a medicine. 1. Its use in modern medicine
Honey has been used as a medicine for thousands of years and its curative properties are well documented. However, modern medicine turned its back on honey and it is only now, with the advent of multi-resistant bacteria, that the antibiotic properties of honey are being rediscovered
Quantum Communication
Quantum communication, and indeed quantum information in general, has changed
the way we think about quantum physics. In 1984 and 1991, the first protocol
for quantum cryptography and the first application of quantum non-locality,
respectively, attracted a diverse field of researchers in theoretical and
experimental physics, mathematics and computer science. Since then we have seen
a fundamental shift in how we understand information when it is encoded in
quantum systems. We review the current state of research and future directions
in this new field of science with special emphasis on quantum key distribution
and quantum networks.Comment: Submitted version, 8 pg (2 cols) 5 fig
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Automated segmentation of cerebral deep gray matter from MRI scans: effect of field strength on sensitivity and reliability
SoLid: A short baseline reactor neutrino experiment
The SoLid experiment, short for Search for Oscillations with a Lithium-6 detector, is a new generation neutrino experiment which tries to address the key challenges for high precision reactor neutrino measurements at very short distances from a reactor core and with little or no overburden. The primary goal of the SoLid experiment is to perform a precise measurement of the electron antineutrino energy spectrum and flux and to search for very short distance neutrino oscillations as a probe of eV-scale sterile neutrinos. This paper describes the SoLid detection principle, the mechanical design and the construction of the detector. It then reports on the installation and commissioning on site near the BR2 reactor, Belgium, and finally highlights its performance in terms of detector response and calibration
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