15,738 research outputs found
Fast Authentication in Heterogeneous Wireless Networks
The growing diffusion of wireless devices is leading to an increasing demand for mobility and security. At the same time, most applications can only tolerate short breaks in the data flow, so that it is a challenge to find out mobility and authentication methods able to cope with these constraints. This paper aims to propose an authentication scheme which significantly shortens the authentication latency and that can be deployed in a variety of wireless environments ranging from common Wireless LANs (WLANs) to satellite-based access networks
From China with love: Effects of the Chinese economy on skill-biased technical change in the US
In this study, we analyze the effects of labor shortage in China on the direction of innovation in the US by incorporating production offshoring into a North-South model of directed technical change. We �find that if offshoring is present (absent) in equilibrium, then a decrease (an increase) in unskilled labor in the South would lead to skill-biased technical change in the North. This fi�nding highlights the different implications of offshoring and conventional trade on innovation. Furthermore, we �find
that an increase in the Southern stock of capital reduces offshoring and also leads to skill-biased technical change. Therefore, rapid capital accumulation and labor shortage
in China could lead to a rising skill premium in the US. Calibrating the model to China-US data, we �find that a 1% decrease in unskilled labor (1% increase in capital)
in China leads to a 0.8% (0.6%) increase in the skill premium in the US under a moderate elasticity of substitution between skill-intensive and labor-intensive goods
Is Traditional Teaching really all that Bad? A Within-Student Between-Subject Approach
Recent studies conclude that teachers are important for student learning but it remains uncertain what actually determines effective teaching. This study directly peers into the black box of educational production by investigating the relationship between lecture style teaching and student achievement. Based on matched student-teacher data for the US, the estimation strategy exploits between-subject variation to control for unobserved student traits. Results indicate that traditional lecture style teaching is associated with significantly higher student achievement. No support for detrimental effects of lecture style teaching can be found even when evaluating possible selection biases due to unobservable teacher characteristics.teaching practices, educational production, TIMSS, between-subject variation
Statistical Analysis of Native Contact Formation in the Folding of Designed Model Proteins
The time evolution of the formation probability of native bonds has been
studied for designed sequences which fold fast into the native conformation.
From this analysis a clear hierarchy of bonds emerge a) local, fast forming
highly stable native bonds built by some of the most strongly interacting amino
acids of the protein, b) non-local bonds formed late in the folding process, in
coincidence with the folding nucleus, and involving essentially the same
strongly interacting amino acids already participating in the fast bonds, c)
the rest of the native bonds whose behaviour is subordinated, to a large
extent, to that of the local- and non-local native contacts
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The Neurobiology of Eating Disorders.
Eating disorders are severe psychiatric illnesses with a typical age of onset in adolescence. Brain research in youth and young adults may help us identify specific neurobiology that contributes to onset and maintenance of those disorders. This article provides a state-of-the-art review of our current understanding of the neurobiology of anorexia nervosa and bulimia nervosa. This includes brain structure and function studies to understand food restriction, binge-eating or purging behaviors, cognitive and emotional factors, as well as interoception. Binge-eating disorder and avoidant restrictive food intake disorder are also discussed, but the literature is still very small
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Recent advances in understanding anorexia nervosa.
Anorexia nervosa is a complex psychiatric illness associated with food restriction and high mortality. Recent brain research in adolescents and adults with anorexia nervosa has used larger sample sizes compared with earlier studies and tasks that test specific brain circuits. Those studies have produced more robust results and advanced our knowledge of underlying biological mechanisms that may contribute to the development and maintenance of anorexia nervosa. It is now recognized that malnutrition and dehydration lead to dynamic changes in brain structure across the brain, which normalize with weight restoration. Some structural alterations could be trait factors but require replication. Functional brain imaging and behavioral studies have implicated learning-related brain circuits that may contribute to food restriction in anorexia nervosa. Most notably, those circuits involve striatal, insular, and frontal cortical regions that drive learning from reward and punishment, as well as habit learning. Disturbances in those circuits may lead to a vicious cycle that hampers recovery. Other studies have started to explore the neurobiology of interoception or social interaction and whether the connectivity between brain regions is altered in anorexia nervosa. All together, these studies build upon earlier research that indicated neurotransmitter abnormalities in anorexia nervosa and help us develop models of a distinct neurobiology that underlies anorexia nervosa
Low-Latency Short-Packet Transmissions: Fixed Length or HARQ?
We study short-packet communications, subject to latency and reliability
constraints, under the premises of limited frequency diversity and no time
diversity. The question addressed is whether, and when, hybrid automatic repeat
request (HARQ) outperforms fixed-blocklength schemes with no feedback (FBL-NF)
in such a setting. We derive an achievability bound for HARQ, under the
assumption of a limited number of transmissions. The bound relies on
pilot-assisted transmission to estimate the fading channel and scaled
nearest-neighbor decoding at the receiver. We compare our achievability bound
for HARQ to stateof-the-art achievability bounds for FBL-NF communications and
show that for a given latency, reliability, number of information bits, and
number of diversity branches, HARQ may significantly outperform FBL-NF. For
example, for an average latency of 1 ms, a target error probability of 10^-3,
30 information bits, and 3 diversity branches, the gain in energy per bit is
about 4 dB.Comment: 6 pages, 5 figures, accepted to GLOBECOM 201
How do neural networks see depth in single images?
Deep neural networks have lead to a breakthrough in depth estimation from
single images. Recent work often focuses on the accuracy of the depth map,
where an evaluation on a publicly available test set such as the KITTI vision
benchmark is often the main result of the article. While such an evaluation
shows how well neural networks can estimate depth, it does not show how they do
this. To the best of our knowledge, no work currently exists that analyzes what
these networks have learned.
In this work we take the MonoDepth network by Godard et al. and investigate
what visual cues it exploits for depth estimation. We find that the network
ignores the apparent size of known obstacles in favor of their vertical
position in the image. Using the vertical position requires the camera pose to
be known; however we find that MonoDepth only partially corrects for changes in
camera pitch and roll and that these influence the estimated depth towards
obstacles. We further show that MonoDepth's use of the vertical image position
allows it to estimate the distance towards arbitrary obstacles, even those not
appearing in the training set, but that it requires a strong edge at the ground
contact point of the object to do so. In future work we will investigate
whether these observations also apply to other neural networks for monocular
depth estimation.Comment: Submitte
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