4,523 research outputs found
ReCon: Revealing and Controlling PII Leaks in Mobile Network Traffic
It is well known that apps running on mobile devices extensively track and
leak users' personally identifiable information (PII); however, these users
have little visibility into PII leaked through the network traffic generated by
their devices, and have poor control over how, when and where that traffic is
sent and handled by third parties. In this paper, we present the design,
implementation, and evaluation of ReCon: a cross-platform system that reveals
PII leaks and gives users control over them without requiring any special
privileges or custom OSes. ReCon leverages machine learning to reveal potential
PII leaks by inspecting network traffic, and provides a visualization tool to
empower users with the ability to control these leaks via blocking or
substitution of PII. We evaluate ReCon's effectiveness with measurements from
controlled experiments using leaks from the 100 most popular iOS, Android, and
Windows Phone apps, and via an IRB-approved user study with 92 participants. We
show that ReCon is accurate, efficient, and identifies a wider range of PII
than previous approaches.Comment: Please use MobiSys version when referencing this work:
http://dl.acm.org/citation.cfm?id=2906392. 18 pages, recon.meddle.mob
The Value of Literacy Practices
The concepts of literacy events and practices have received considerable attention in educational research and policy. In comparison, the question of value, that is, ‘which literacy practices do people most value?’ has been neglected. With the current trend of cross-cultural adult literacy assessment, it is increasingly important to recognise locally valued literacy practices. In this paper we argue that measuring preferences and weighting of literacy practices provides an empirical and democratic basis for decisions in literacy assessment and curriculum development and could inform rapid educational adaptation to changes in the literacy environment. The paper examines the methodological basis for investigating literacy values and its potential to inform cross-cultural literacy assessments. The argument is illustrated with primary data from Mozambique. The correlation between individual values and respondents’ socio-economic and demographic characteristics is explored
A Monitoring Campaign for Luhman 16AB. I. Detection of Resolved Near-Infrared Spectroscopic Variability
[abbreviated] We report resolved near-infrared spectroscopic monitoring of
the nearby L dwarf/T dwarf binary WISE J104915.57-531906.1AB (Luhman 16AB), as
part of a broader campaign to characterize the spectral energy distribution and
temporal variability of this system. A continuous 45-minute sequence of
low-resolution IRTF/SpeX data spanning 0.8-2.4 micron were obtained, concurrent
with combined-light optical photometry with ESO/TRAPPIST. Our spectral
observations confirm the flux reversal of this binary, and we detect a
wavelength-dependent decline in the relative spectral fluxes of the two
components coincident with a decline in the combined-light optical brightness
of the system over the course of the observation. These data are successfully
modeled as a combination of brightness and color variability in the T0.5 Luhman
16B, consistent cloud variations; and no significant variability in L7.5 Luhman
16A. We estimate a peak-to-peak amplitude of 13.5% at 1.25 micron over the full
lightcurve. Using a two-spot brightness temperature model, we infer an average
cloud covering fraction of ~30-55% for Luhman 16B, varying by 15-30% over a
rotation period. A Rhines scale interpretation for the size of the variable
features explains an apparent correlation between period and amplitude for
three highly variable T dwarfs, and predicts relatively fast winds (1-3 km/s)
for Luhman 16B consistent with lightcurve evolution on an advective time scale
(1-3 rotation periods). Our observations support the model of a patchy
disruption of the mineral cloud layer as a universal feature of the L dwarf/T
dwarf transition.Comment: 11 pages, 7 figures; accepted for publication in Astrophysical
Journa
Literacy under and over the desk: oppositions and heterogeneity
In this paper I argue that a dominant theme in New Literacy Studies research, the differences between literacy practices inside and outside school, has sometimes involved conflating ‘home literacy’ with private, unregulated ‘vernacular literacy’, and the use of an idealised abstract notion of schooled literacy to represent students’ actual everyday experience in the classroom. Drawing on linguistic ethnographic research in two British primary schools, I use examples of ‘unofficial’ and ‘official’ literacy activities from 10-11 year-olds to show that a wide range of different forms of literacy can be found in the classroom and I argue that the division between ‘vernacular’ and ‘schooled’ is not as clear-cut as is sometimes assumed. My analysis of children’s literacy activities suggests that, on the one hand, unofficial activities orientate towards and index official knowledges and the macro-level institutional order and, on the other hand, official activities are interpenetrated with informal practices and procedures. I also comment on some implications of using the New Literacy Studies ‘events and practices’ conceptual framework for understanding what is going on in classrooms
Application of a dynamic subgrid-scale model to turbulent recirculating flows
The dynamic subgrid-scale model of Germano et al. is implemented in a finite volume formulation and applied to the simulation of turbulent flow in a three-dimensional lid-driven cavity at Reynolds number of 7500. The filtering operation is carried out in physical space, and the model coefficient is calculated locally. The computed mean and rms velocities as well as the Reynolds stress are compared with experimental data. It is shown that backscatter from small to large scales is necessary to sustain turbulent fluctuations. The model is being applied to the simulation of turbulent flows in a stratified and rotating environment in complex geometries
Improving adaptive bagging methods for evolving data streams
We propose two new improvements for bagging methods on evolving data streams. Recently, two new variants of Bagging were proposed: ADWIN Bagging and Adaptive-Size Hoeffding Tree (ASHT) Bagging. ASHT Bagging uses trees of different sizes, and ADWIN Bagging uses ADWIN as a change detector to decide when to discard underperforming ensemble members. We improve ADWIN Bagging using Hoeffding Adaptive Trees, trees that can adaptively learn from data streams that change over time. To speed up the time for adapting to change of Adaptive-Size Hoeffding Tree (ASHT) Bagging, we add an error change detector for each classifier. We test our improvements by performing an evaluation study on synthetic and real-world datasets comprising up to ten million examples
Optimizing DNA Extraction Methods for Nanopore Sequencing of Neisseria gonorrhoeae Directly from Urine Samples
Empirical gonorrhea treatment at initial diagnosis reduces onward transmission. However, increasing resistance to multiple antibiotics may necessitate waiting for culture-based diagnostics to select an effective treatment. There is a need for same-day culture-free diagnostics that identify infection and detect antimicrobial resistance. We investigated if Nanopore sequencing can detect sufficient Neisseria gonorrhoeae DNA to reconstruct whole genomes directly from urine samples. We used N. gonorrhoeae-spiked urine samples and samples from gonorrhea infections to determine optimal DNA extraction methods that maximize the amount of N. gonorrhoeae DNA sequenced while minimizing contaminating host DNA. In simulated infections, the Qiagen UCP pathogen mini kit provided the highest ratio of N. gonorrhoeae to human DNA and the most consistent results. Depletion of human DNA with saponin increased N. gonorrhoeae yields in simulated infections but decreased yields in clinical samples. In 10 urine samples from men with symptomatic urethral gonorrhea, ≥92.8% coverage of an N. gonorrhoeae reference genome was achieved in all samples, with ≥93.8% coverage breath at ≥10-fold depth in 7 (70%) samples. In simulated infections, if ≥104 CFU/ml of N. gonorrhoeae was present, sequencing of the large majority of the genome was frequently achieved. N. gonorrhoeae could also be detected from urine in cobas PCR medium tubes and from urethral swabs and in the presence of simulated Chlamydia coinfection. Using Nanopore sequencing of urine samples from men with urethral gonorrhea, sufficient data can be obtained to reconstruct whole genomes in the majority of samples without the need for culture
Magnetic Field scaling of Relaxation curves in Small Particle Systems
We study the effects of the magnetic field on the relaxation of the
magnetization of small monodomain non-interacting particles with random
orientations and distribution of anisotropy constants. Starting from a master
equation, we build up an expression for the time dependence of the
magnetization which takes into account thermal activation only over barriers
separating energy minima, which, in our model, can be computed exactly from
analytical expressions. Numerical calculations of the relaxation curves for
different distribution widths, and under different magnetic fields H and
temperatures T, have been performed. We show how a \svar scaling of the
curves, at different T and for a given H, can be carried out after proper
normalization of the data to the equilibrium magnetization. The resulting
master curves are shown to be closely related to what we call effective energy
barrier distributions, which, in our model, can be computed exactly from
analytical expressions. The concept of effective distribution serves us as a
basis for finding a scaling variable to scale relaxation curves at different H
and a given T, thus showing that the field dependence of energy barriers can be
also extracted from relaxation measurements.Comment: 12 pages, 9 figures, submitted to Phys. Rev.
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