548 research outputs found
The Homeric poems as oral dictated texts
The more I understand the Southslavic poetry and the nature of the unity of the oral poem, the clearer it seems to me that the Iliad and the Odyssey are very exactly, as we have them, each one of them the rounded and finished work of a single singer…. I even figure to myself, just now, the moment when the author of the Odyssey sat and dictated his song, while another, with writing materials, wrote it down verse by verse, even in the way that our singers sit in the immobility of their thought, watching the motion of Nikola's hand across the empty page, when it will tell them it is the instant for them to speak the next verse
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Detailed examination of a packet collision model for Bluetooth Low Energy advertising mode
The aim of this paper is to investigate the amount of energy that is required to successfully transmit information inside the Bluetooth Low Energy (BLE) advertising packets. There are applications that require more than one BLE node to simultaneously transmit data. The BLE protocol utilizes a specific communication method termed advertising mode to perform unidirectional broadcasts of data from the advertising devices. However, with an increased number of BLE devices advertising simultaneously, there will be inevitable packet collisions from the advertising devices. This results in a waste of energy, specifically in low-power applications where lower consumption is desirable to minimize the need for battery replacements. This paper examines a packet collision model for the BLE advertising mode with the results validated using experimental data. Our analysis shows that when the throughput of the BLE network starts to fall due to an increase in the number of packet collisions, the energy consumption of the BLE nodes increase exponentially with respect to the number of nodes
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Analysis of recovery effect in supercapacitors for wearable devices
Supercapacitors are likely to be adopted as power sources for wearable sensors; in particular where the sensor mechanism relies on energy harvesting. A specific advantage of supercapacitors over traditional batteries is their performance over large numbers of discharge cycles. Likewise, in the case of wearable devices, it is essential to efficiently manage the available power. Supercapacitors exhibit a small recovery effect, in part due to ion diffusion. Modelling this effect allows an increase in available energy to be realized following the sleep times during a discharge cycle thus increasing the time between charging for wearables. This paper presents the increase in useful lifetime that can be achieved via the recovery effect in a typical wearable device
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Reconstruction of Angular Kinematics From Wrist-Worn Inertial Sensor Data for Smart Home Healthcare
This paper tackles the problem of the estimation of simplified human limb kinematics for home health care. Angular kinematics are widely used for gait analysis, for rehabilitation, and more generally for activity recognition. Residential monitoring requires particular sensor constraints to enable long-term user compliance. The proposed strategy is based on measurements from two low-power accelerometers placed only on the forearm, which makes it an ill-posed problem. The system is considered in a Bayesian framework, with a linear-Gaussian transition model with hard boundaries and a nonlinear-Gaussian observation model. The state vector and the associated covariance are estimated by a post-regularized particle filter (constrained-extended-RPF or C-ERPF), with an importance function whose moments are computed via an extended Kalman filter (EKF) linearization. Several sensor configurations are compared in terms of estimation performance, as well as power consumption and user acceptance. The proposed constrained-EKF (CERPF) is compared to other methods (EKF, constrained-EKF, and ERPF without transition constraints) on the basis of simulations and experimental measurements with motion capture reference. The proposed C-ERPF method coupled with two accelerometers on the wrist provides promising results with 19% error in average on both angles, compared with the motion capture reference, 10% on velocities and 7% on accelerations. This comparison highlights that arm kinematics can be estimated from only two accelerometers on the wrist. Such a system is a crucial step toward enabling machine monitoring of users health and activity on a daily basis
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Dictionary memory based software architecture for distributed bluetooth low energy host controllers enabling high coverage in consumer residential healthcare environments
Technology has been seen as a possible solution to the increasing costs of healthcare and the globally aging population. It is known that many elderly people prefer to stay in their homes for as long as possible and remote monitoring can be a solution, but often such systems lack useful information or are prohibitive due to cost, ease of use/deployment and wireless coverage.
This work presents a novel gateway software architecture based on threads being managed by dictionary memory. The architecture has been deployed in a distributed interconnected set of low-cost consumer grade gateway devices using Bluetooth Low Energy (BLE) that are positioned around the home. The gateway devices can then be used to listen, monitor or connect to BLE based healthcare sensors to continually reveal information about the user with full residential coverage. A further novelty of this work is the ability to maintain handover connections between many sensors and many gateways as a user moves throughout their home, thus the gateways can route information to/from sensors across the consumer’s home network. The system has been tested in an experimental house and is now poised to be initially deployed to 100 homes for residential healthcare monitoring before any public mass consumer deployment
Defective Transcriptional Programming of Effector CD8 T Cells in Aged Mice Is Cell-Extrinsic and Can Be Corrected by Administration of IL-12 and IL-18
In response to infection with intracellular microorganisms, old mice mobilize decreased numbers of antigen-specific CD8 T cells with reduced expression of effector molecules and impaired cytolytic activity. Molecular mechanisms behind these defects and the cell-intrinsic (affecting naïve CD8 T cells themselves) vs. extrinsic, microenvironmental origin of such defects remain unclear. Using reciprocal transfer experiments of highly purified naïve T cells from adult and old transgenic OT-1 mice, we decisively show that the dominant effect is cell-extrinsic. Naïve adult OT-1 T cells failed to expand and terminally differentiate in the old organism infected with Listeria-OVA. This defect was preceded by blunted expression of the master transcription factor T-bet and impaired glycolytic switch when T cells are primed in the old organism. However, both old and adult naïve CD8 T cells proliferated and produced effector molecules to a similar extent when stimulated in vitro with polyclonal stimuli, as well as when transferred into adult recipients. Multiple inflammatory cytokines with direct effects on T cell effector differentiation were decreased in spleens of old animals, particularly IL-12 and IL-18. Of note, in vivo treatment of mice with IL-12 and IL-18 on days 4–6 of Listeria infection reconstituted cytotoxic T cell response of aged mice to the level of adult. Therefore, critical cytokine signals which are underproduced in the old priming environment can restore proper transcriptional programming of old naïve CD8 T cells and improve immune defense against intracellular microorganisms
Phase Fluctuations and Pseudogap Properties: Influence of Nonmagnetic Impurities
The presence of nonmagnetic impurities in a 2D ``bad metal'' depresses the
superconducting Berezinskii-Kosterlitz-Thouless transition temperature, while
leaving the pairing energy scale unchanged. Thus the region of the pseudogap
non-superconducting phase, where the modulus of the order parameter is non-zero
but its phase is random, and which opens at the pairing temperature is
substantially bigger than for the clean system. This supports the premise that
fluctuations in the phase of the order parameter can in principle describe the
pseudogap phenomena in high- materials over a rather wide range of
temperatures and carrier densities. The temperature dependence of the bare
superfluid density is also discussed.Comment: 11 pages, LaTeX, 1 EPS figure; final version to appear in
Low.Temp.Phy
Parity-Affected Superconductivity in Ultrasmall Metallic Grains
We investigate the breakdown of BCS superconductivity in {\em ultra}\/small
metallic grains as a function of particle size (characterized by the mean
spacing between discrete electronic eigenstates), and the parity ( =
even/odd) of the number of electrons on the island. Assuming equally spaced
levels, we solve the parity-dependent BCS gap equation for the order parameter
. Both the critical level spacing and the
critical temperature at which are parity
dependent, and both are so much smaller in the odd than the even case that
these differences should be measurable in current experiments.Comment: 4 pages RevTeX, 1 encapsulated postscript figure, submitted to
Physical Review Letter
Parity Effect and Charge Binding Transition in Submicron Josephson Junction Arrays
We reconsider the issue of Berezinskii-Kosterlitz-Thouless (BKT) transition
into an insulating state in the Coulomb-dominated Josephson junction arrays. We
show that previously predicted picture of the Cooper-pair BKT transtion at T =
T_2 is valid only under the condition that T_2 is considerably below the
parity-effect temperature (which is usually almost 10 times below the value of
superconductive transition temperature), and even in this case it is not a
rigorous phase transition but only a crossover, whereas the real phase
transition takes place at T_1 = T_2/4. Our theory is in agreement with
available experimental data on Coulomb-dominated Josephson arrays and also
sheds some light on the origin of unusual reentrant temperature dependence of
resistivity in the array with nearly-criticial ratio of Coulomb to Josephson
energies.Comment: 4 pages, Revtex, to be published in JETP Letters, April 9
Examining the Link between Crime and Unemployment: A Time Series Analysis for Canada
We use national and regional Canadian data to analyse the relationship between economic activity (as reflected by the unemployment rate) and crime rates. Given potential aggregation bias, we disaggregate the crime data and look at the relationship between six different types of crimes rates and unemployment rate; we also disaggregate the data by region. We employ an error correction model in our analysis to test for short-run and long-run dynamics. We find no evidence of long-run relationship between crime and unemployment, when we look at both disaggregation by type of crime and disaggregation by region. Lack of evidence of a long-run relationship indicates we have no evidence of the motivation hypothesis. For selected types of property crimes, we find some evidence of a significant negative short-run relationship between crime and unemployment, lending support to the opportunity hypothesis. Inclusion of control variables in the panel analysis does not alter the findings, qualitatively or quantitatively
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