5,053 research outputs found
Computational Soundness for Dalvik Bytecode
Automatically analyzing information flow within Android applications that
rely on cryptographic operations with their computational security guarantees
imposes formidable challenges that existing approaches for understanding an
app's behavior struggle to meet. These approaches do not distinguish
cryptographic and non-cryptographic operations, and hence do not account for
cryptographic protections: f(m) is considered sensitive for a sensitive message
m irrespective of potential secrecy properties offered by a cryptographic
operation f. These approaches consequently provide a safe approximation of the
app's behavior, but they mistakenly classify a large fraction of apps as
potentially insecure and consequently yield overly pessimistic results.
In this paper, we show how cryptographic operations can be faithfully
included into existing approaches for automated app analysis. To this end, we
first show how cryptographic operations can be expressed as symbolic
abstractions within the comprehensive Dalvik bytecode language. These
abstractions are accessible to automated analysis, and they can be conveniently
added to existing app analysis tools using minor changes in their semantics.
Second, we show that our abstractions are faithful by providing the first
computational soundness result for Dalvik bytecode, i.e., the absence of
attacks against our symbolically abstracted program entails the absence of any
attacks against a suitable cryptographic program realization. We cast our
computational soundness result in the CoSP framework, which makes the result
modular and composable.Comment: Technical report for the ACM CCS 2016 conference pape
Exploring decision making by occupational therapists in a school setting
Occupational therapists working in schools make many decisions regarding evaluation and services to support a student\u27s special education. Six school-based occupational therapists from the Midwest shared, through interviews, how they chose assessment methods and tools for a particular student and how their evaluation findings were used to make service delivery decisions for that student. This group of therapists addressed team members\u27 concerns, focusing on how sensory processing, handwriting, and functional skills influence a student\u27s schoolwork performance. Their decisions regarding assessments were determined by the needs of the student and the questions raised by the educational team. Their evaluation information contributed to team decision-making regarding services and resulted in a variety of service delivery models. The results acknowledge the linearity of thinking used by school occupational therapists
The JPL telerobotic Manipulator Control and Mechanization (MCM) subsystem
The Manipulator Control and Mechanization (MCM) subsystem of the telerobot system provides the real-time control of the robot manipulators in autonomous and teleoperated modes and real time input/output for a variety of sensors and actuators. Substantial hardware and software are included in this subsystem which interfaces in the hierarchy of the telerobot system with the other subsystems. The other subsystems are: run time control, task planning and reasoning, sensing and perception, and operator control subsystem. The architecture of the MCM subsystem, its capabilities, and details of various hardware and software elements are described. Important improvements in the MCM subsystem over the first version are: dual arm coordinated trajectory generation and control, addition of integrated teleoperation, shared control capability, replacement of the ultimate controllers with motor controllers, and substantial increase in real time processing capability
Mitochondrial DNA insertions into the nuclear chromosomes of the maize Mo17 inbred line [abstract]
Abstract only availableMitochondria contain their own DNA separate from the nucleus; however, most of their genes have been transferred to the nucleus over evolutionary time. The lateral transfer of DNA from the mitochondria to the nucleus appears to be a continuing process and is more frequent in plants than in animals. Our laboratory has documented extensive variation in the nuclear-mitochondrial sequences (NUMTs) among maize inbred lines using total mitochondrial DNA (mtDNA) as probes onto mitotic metaphase chromosomes, a technique known as fluorescence in situ hybridization (FISH). The mitochondrial genome has been cloned into 20 cosmids, which were used to examine the insertions of individual segments. The focus of the current study was to use FISH with the 20 individual mtDNA-containing cosmids to locate mtDNA within the nuclear chromosomes of the Mo17 inbred line of maize and to compare these locations with those of the B73 line. We studied Mo17 because this line and its derivatives are used in crosses with B73-derived lines to create the most commonly used corn hybrids. Fifteen NUMTs had been detected on the Mo17 chromosomes using a mixture of 19 mtDNA-containing cosmids. However, only nine of the 15 NUMTs were seen when applying individual mtDNA-containing cosmids, suggesting that the portions of nuclear DNA corresponding to the individual mtDNA-containing cosmids were too small to be detected until many cosmids were combined. A large NUMT was previously detected on the long arm of chromosome 9 by 14 of the 20 individually tested cosmids in the B73 inbred line. However, a NUMT present at the same site in Mo17 was detected by only 2 of the 20 cosmids (5 and 20). This suggests that the major insertion in B73 is recent and that it may have inserted by homologous recombination
X-Ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu
We have used a MHz lock-in x-ray spectro-microscopy technique to directly
detect changes of magnetic moments in Cu due to spin injection from an adjacent
Co layer. The elemental and chemical specificity of x-rays allows us to
distinguish two spin current induced effects. We detect the creation of
transient magnetic moments of on Cu atoms
within the bulk of the 28 nm thick Cu film due to spin-accumulation. The moment
value is compared to predictions by Mott's two current model. We also observe
that the hybridization induced existing magnetic moments on Cu interface atoms
are transiently increased by about 10% or .
This reveals the dominance of spin-torque alignment over Joule heat induced
disorder of the interfacial Cu moments during current flow
Disentangling surface and bulk transport in topological-insulator - junctions
By combining -type and -type
topological insulators, vertically stacked - junctions can be formed,
allowing to position the Fermi level into the bulk band gap and also tune
between - and -type surface carriers. Here we use low-temperature
magnetotransport measurements to probe the surface and bulk transport modes in
a range of vertical heterostructures with varying
relative thicknesses of the top and bottom layers. With increasing thickness of
the layer we observe a change from - to -type
behavior via a specific thickness where the Hall signal is immeasurable.
Assuming that the the bulk and surface states contribute in parallel, we can
calculate and reproduce the dependence of the Hall and longitudinal components
of resistivity on the film thickness. This highlights the role played by the
bulk conduction channels which, importantly, cannot be probed using surface
sensitive spectroscopic techniques. Our calculations are then buttressed by a
semi-classical Boltzmann transport theory which rigorously shows the vanishing
of the Hall signal. Our results provide crucial experimental and theoretical
insights into the relative roles of the surface and bulk in the vertical
topological - junctions.Comment: 11 pages, 5 figure
Towards Inferring Mechanical Lock Combinations using Wrist-Wearables as a Side-Channel
Wrist-wearables such as smartwatches and fitness bands are equipped with a
variety of high-precision sensors that support novel contextual and
activity-based applications. The presence of a diverse set of on-board sensors,
however, also expose an additional attack surface which, if not adequately
protected, could be potentially exploited to leak private user information. In
this paper, we investigate the feasibility of a new attack that takes advantage
of a wrist-wearable's motion sensors to infer input on mechanical devices
typically used to secure physical access, for example, combination locks. We
outline an inference framework that attempts to infer a lock's unlock
combination from the wrist motion captured by a smartwatch's gyroscope sensor,
and uses a probabilistic model to produce a ranked list of likely unlock
combinations. We conduct a thorough empirical evaluation of the proposed
framework by employing unlocking-related motion data collected from human
subject participants in a variety of controlled and realistic settings.
Evaluation results from these experiments demonstrate that motion data from
wrist-wearables can be effectively employed as a side-channel to significantly
reduce the unlock combination search-space of commonly found combination locks,
thus compromising the physical security provided by these locks
Direct observation and imaging of a spin-wave soliton with like symmetry
The prediction and realization of magnetic excitations driven by electrical
currents via the spin transfer torque effect, enables novel magnetic
nano-devices where spin-waves can be used to process and store information. The
functional control of such devices relies on understanding the properties of
non-linear spin-wave excitations. It has been demonstrated that spin waves can
show both an itinerant character, but also appear as localized solitons. So
far, it was assumed that localized solitons have essentially cylindrical,
like symmetry. Using a newly developed high-sensitivity time-resolved
magnetic x-ray microscopy, we instead observe the emergence of a novel
localized soliton excitation with a nodal line, i.e. with like symmetry.
Micromagnetic simulations identify the physical mechanism that controls the
transition from to like solitons. Our results suggest a potential new
pathway to design artificial atoms with tunable dynamical states using
nanoscale magnetic devices
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