163,945 research outputs found
Can sign language make you better at hand processing?
The languages developed by deaf communities are unique for using visual signs produced by the hand. In the present study, we explored the cognitive effects of employing the hand as articulator. We focused on the arbitrariness of the form-meaning relationship\u2014a fundamental feature of natural languages\u2014and asked whether sign languages change the processing of arbitrary non-linguistic stimulus-response (S-R) associations involving the hand. This was tested using the Simon effect, which specifically requires such type of associations. Differences between signers and speakers (non-signers) only appeared in the Simon task when hand stimuli were shown. Response-time analyses revealed that the distinctiveness of signers\u2019 responses derived from an increased ability to process memory traces of arbitrary S-R pairs related to the hand. These results shed light on the interplay between language and cognition as well as on the effects of sign language acquisition
Integration of Carrier Aggregation and Dual Connectivity for the ns-3 mmWave Module
Thanks to the wide availability of bandwidth, the millimeter wave (mmWave)
frequencies will provide very high data rates to mobile users in next
generation 5G cellular networks. However, mmWave links suffer from high
isotropic pathloss and blockage from common materials, and are subject to an
intermittent channel quality. Therefore, protocols and solutions at different
layers in the cellular network and the TCP/IP protocol stack have been proposed
and studied. A valuable tool for the end-to-end performance analysis of mmWave
cellular networks is the ns-3 mmWave module, which already models in detail the
channel, Physical (PHY) and Medium Access Control (MAC) layers, and extends the
Long Term Evolution (LTE) stack for the higher layers. In this paper we present
an implementation for the ns-3 mmWave module of multi connectivity techniques
for 3GPP New Radio (NR) at mmWave frequencies, namely Carrier Aggregation (CA)
and Dual Connectivity (DC), and discuss how they can be integrated to increase
the functionalities offered by the ns-3 mmWave module.Comment: 9 pages, 7 figures, submitted to the Workshop on ns-3 (WNS3) 201
Performance Comparison of Dual Connectivity and Hard Handover for LTE-5G Tight Integration
Communications at frequencies above 10 GHz (the mmWave band) are expected to
play a major role for the next generation of cellular networks (5G), because of
the potential multi-gigabit, ultra-low latency performance of this technology.
mmWave frequencies however suffer from very high isotropic pathloss, which may
result in cells with a much smaller coverage area than current LTE macrocells.
High directionality techniques will be used to improve signal quality and
extend coverage area, along with a high density deployment of mmWave base
stations (BS). However, when propagation conditions are hard and it is
difficult to provide high quality coverage with mmWave BS, it is necessary to
rely on previous generation LTE base stations, which make use of lower
frequencies (900 MHz - 3.5 GHz), which are less sensitive to blockage and
experience lower pathloss. In order to provide ultra-reliable services to
mobile users there is a need for network architectures that tightly and
seamlessly integrate the LTE and mmWave Radio Access Technologies. In this
paper we will present two possible alternatives for this integration and show
how simulation tools can be used to assess and compare their performance.Comment: This paper was accepted for presentation at the ninth EAI SIMUtools
2016 conference, August 22 - 23, 2016, Prague, Czech Republi
TCP in 5G mmWave Networks: Link Level Retransmissions and MP-TCP
MmWave communications, one of the cornerstones of future 5G mobile networks,
are characterized at the same time by a potential multi-gigabit capacity and by
a very dynamic channel, sensitive to blockage, wide fluctuations in the
received signal quality, and possibly also sudden link disruption. While the
performance of physical and MAC layer schemes that address these issues has
been thoroughly investigated in the literature, the complex interactions
between mmWave links and transport layer protocols such as TCP are still
relatively unexplored. This paper uses the ns-3 mmWave module, with its channel
model based on real measurements in New York City, to analyze the performance
of the Linux TCP/IP stack (i) with and without link-layer retransmissions,
showing that they are fundamental to reach a high TCP throughput on mmWave
links and (ii) with Multipath TCP (MP-TCP) over multiple LTE and mmWave links,
illustrating which are the throughput-optimal combinations of secondary paths
and congestion control algorithms in different conditions.Comment: 6 pages, 11 figures, accepted for presentation at the 2017 IEEE
Conference on Computer Communications Workshops (INFOCOM WKSHPS
Repulsion-Sustained Supercurrent and Flux Quantization in Rings of Symmetric Hubbard Clusters
We test the response to a threading magnetic field of rings of 5-site
-symmetric repulsive Hubbard clusters connected by weak intercell
links; each 5-site unit has the topology of a CuO cluster and a repulsive
interaction is included on every site. In a numerical study of the three-unit
ring with 8 particles, we take advantage of a novel exact-diagonalization
technique which can be generally applied to many-fermion problems. For O-O
hopping we find Superconducting Flux Quantization (SFQ), but for purely Cu-Cu
links bound pair propagation is hindered by symmetry. The results agree with
W=0 pairing theory.Comment: 4 pages, 2 figure
An efficient and accurate decomposition of the Fermi operator
We present a method to compute the Fermi function of the Hamiltonian for a
system of independent fermions, based on an exact decomposition of the
grand-canonical potential. This scheme does not rely on the localization of the
orbitals and is insensitive to ill-conditioned Hamiltonians. It lends itself
naturally to linear scaling, as soon as the sparsity of the system's density
matrix is exploited. By using a combination of polynomial expansion and
Newton-like iterative techniques, an arbitrarily large number of terms can be
employed in the expansion, overcoming some of the difficulties encountered in
previous papers. Moreover, this hybrid approach allows us to obtain a very
favorable scaling of the computational cost with increasing inverse
temperature, which makes the method competitive with other Fermi operator
expansion techniques. After performing an in-depth theoretical analysis of
computational cost and accuracy, we test our approach on the DFT Hamiltonian
for the metallic phase of the LiAl alloy.Comment: 8 pages, 7 figure
Rate-Distortion Classification for Self-Tuning IoT Networks
Many future wireless sensor networks and the Internet of Things are expected
to follow a software defined paradigm, where protocol parameters and behaviors
will be dynamically tuned as a function of the signal statistics. New protocols
will be then injected as a software as certain events occur. For instance, new
data compressors could be (re)programmed on-the-fly as the monitored signal
type or its statistical properties change. We consider a lossy compression
scenario, where the application tolerates some distortion of the gathered
signal in return for improved energy efficiency. To reap the full benefits of
this paradigm, we discuss an automatic sensor profiling approach where the
signal class, and in particular the corresponding rate-distortion curve, is
automatically assessed using machine learning tools (namely, support vector
machines and neural networks). We show that this curve can be reliably
estimated on-the-fly through the computation of a small number (from ten to
twenty) of statistical features on time windows of a few hundreds samples
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