1,569 research outputs found
Exposing Fake Images with Forensic Similarity Graphs
We propose new image forgery detection and localization algorithms by
recasting these problems as graph-based community detection problems. To do
this, we introduce a novel abstract, graph-based representation of an image,
which we call the Forensic Similarity Graph, that captures key forensic
relationships among regions in the image. In this representation, small image
patches are represented by graph vertices with edges assigned according to the
forensic similarity between patches. Localized tampering introduces unique
structure into this graph, which aligns with a concept called ``community
structure'' in graph-theory literature. In the Forensic Similarity Graph,
communities correspond to the tampered and unaltered regions in the image. As a
result, forgery detection is performed by identifying whether multiple
communities exist, and forgery localization is performed by partitioning these
communities. We present two community detection techniques, adapted from
literature, to detect and localize image forgeries. We experimentally show that
our proposed community detection methods outperform existing state-of-the-art
forgery detection and localization methods, which do not capture such community
structure.Comment: 16 pages, under review at IEEE Journal of Selected Topics in Signal
Processin
Joint Demosaicing and Denoising with Double Deep Image Priors
Demosaicing and denoising of RAW images are crucial steps in the processing
pipeline of modern digital cameras. As only a third of the color information
required to produce a digital image is captured by the camera sensor, the
process of demosaicing is inherently ill-posed. The presence of noise further
exacerbates this problem. Performing these two steps sequentially may distort
the content of the captured RAW images and accumulate errors from one step to
another. Recent deep neural-network-based approaches have shown the
effectiveness of joint demosaicing and denoising to mitigate such challenges.
However, these methods typically require a large number of training samples and
do not generalize well to different types and intensities of noise. In this
paper, we propose a novel joint demosaicing and denoising method, dubbed
JDD-DoubleDIP, which operates directly on a single RAW image without requiring
any training data. We validate the effectiveness of our method on two popular
datasets -- Kodak and McMaster -- with various noises and noise intensities.
The experimental results show that our method consistently outperforms other
compared methods in terms of PSNR, SSIM, and qualitative visual perception
Tregs self-organize into a computing ecosystem and implement a sophisticated optimization algorithm for mediating immune response
Regulatory T cells (Tregs) play a crucial role in mediating immune response. Yet an algorithmic understanding of the role of Tregs in adaptive immunity remains lacking. Here, we present a biophysically realistic model of Treg-mediated self-tolerance in which Tregs bind to self-antigens and locally inhibit the proliferation of nearby activated T cells. By exploiting a duality between ecological dynamics and constrained optimization, we show that Tregs tile the potential antigen space while simultaneously minimizing the overlap between Treg activation profiles. We find that for sufficiently high Treg diversity, Treg-mediated self-tolerance is robust to fluctuations in self-antigen concentrations but lowering the Treg diversity results in a sharp transition-related to the Gardner transition in perceptrons-to a regime where changes in self-antigen concentrations can result in an autoimmune response. We propose an experimental test of this transition in immune-deficient mice and discuss potential implications for autoimmune diseases
Tregs self-organize into a "computing ecosystem" and implement a sophisticated optimization algorithm for mediating immune response
Regulatory T cells (Tregs) play a crucial role in mediating immune response.
Yet an algorithmic understanding of the role of Tregs in adaptive immunity
remains lacking. Here, we present a biophysically realistic model of Treg
mediated self-tolerance in which Tregs bind to self-antigens and locally
inhibit the proliferation of nearby activated T cells. By exploiting a duality
between ecological dynamics and constrained optimization, we show that Tregs
tile the potential antigen space while simultaneously minimizing the overlap
between Treg activation profiles. We find that for sufficiently high Treg
diversity, Treg mediated self-tolerance is robust to fluctuations in
self-antigen concentrations but lowering the Treg diversity results in a sharp
transition -- related to the Gardner transition in perceptrons -- to a regime
where changes in self-antigen concentrations can result in an auto-immune
response. We propose a novel experimental test of this transition in
immune-deficient mice and discuss potential implications for autoimmune
diseases.Comment: 8 pages, 4 figures + Appendix; Accepted at PNA
Numerical investigation of conjugated heat transfer in a channel with a moving depositing front
This article presents numerical simulations of conjugated heat transfer in a fouled channel with a moving depositing front. The depositing front separating the fluid and the deposit layer is captured using the level-set method. Fluid flow is modeled by the incompressible Navier–Stokes equations. Numerical solution is performed on a fixed mesh using the finite volume method. The effects of Reynolds number and thermal conductivity ratio between the deposit layer and the fluid on local Nusselt number as well as length-averaged Nusselt number are investigated. It is found that heat transfer performance, represented by the local and length-averaged Nusselt number reduces significantly in a fouled channel compared with that in a clean channel. Heat transfer performance decreases with the growth of the deposit layer. Increases in Reynolds, Prandtl numbers both enhance heat transfer. Besides, heat transfer is enhanced when the thermal conductivity ratio between the deposit layer and the fluid is lower than 20 but it decreases when the thermal conductivity ratio is larger than 2
The zooarchaeological application of quantifying cranial shape differences in wild boar and domestic pigs (Sus scrofa) using 3D geometric morphometrics
Peer reviewedPublisher PD
Epidural Hematoma Following Cervical Spine Surgery.
STUDY DESIGN: A multicentered retrospective case series.
OBJECTIVE: To determine the incidence and circumstances surrounding the development of a symptomatic postoperative epidural hematoma in the cervical spine.
METHODS: Patients who underwent cervical spine surgery between January 1, 2005, and December 31, 2011, at 23 institutions were reviewed, and all patients who developed an epidural hematoma were identified.
RESULTS: A total of 16 582 cervical spine surgeries were identified, and 15 patients developed a postoperative epidural hematoma, for a total incidence of 0.090%. Substantial variation between institutions was noted, with 11 sites reporting no epidural hematomas, and 1 site reporting an incidence of 0.76%. All patients initially presented with a neurologic deficit. Nine patients had complete resolution of the neurologic deficit after hematoma evacuation; however 2 of the 3 patients (66%) who had a delay in the diagnosis of the epidural hematoma had residual neurologic deficits compared to only 4 of the 12 patients (33%) who had no delay in the diagnosis or treatment (P = .53). Additionally, the patients who experienced a postoperative epidural hematoma did not experience any significant improvement in health-related quality-of-life metrics as a result of the index procedure at final follow-up evaluation.
CONCLUSION: This is the largest series to date to analyze the incidence of an epidural hematoma following cervical spine surgery, and this study suggest that an epidural hematoma occurs in approximately 1 out of 1000 cervical spine surgeries. Prompt diagnosis and treatment may improve the chance of making a complete neurologic recovery, but patients who develop this complication do not show improvements in the health-related quality-of-life measurements
Origin of volatiles in the Main Belt
We propose a scenario for the formation of the Main Belt in which asteroids
incorporated icy particles formed in the outer Solar Nebula. We calculate the
composition of icy planetesimals formed beyond a heliocentric distance of 5 AU
in the nebula by assuming that the abundances of all elements, in particular
that of oxygen, are solar. As a result, we show that ices formed in the outer
Solar Nebula are composed of a mix of clathrate hydrates, hydrates formed above
50 K and pure condensates produced at lower temperatures. We then consider the
inward migration of solids initially produced in the outer Solar Nebula and
show that a significant fraction may have drifted to the current position of
the Main Belt without encountering temperature and pressure conditions high
enough to vaporize the ices they contain. We propose that, through the
detection and identification of initially buried ices revealed by recent
impacts on the surfaces of asteroids, it could be possible to infer the
thermodynamic conditions that were present within the Solar Nebula during the
accretion of these bodies, and during the inward migration of icy
planetesimals. We also investigate the potential influence that the
incorporation of ices in asteroids may have on their porosities and densities.
In particular, we show how the presence of ices reduces the value of the bulk
density of a given body, and consequently modifies its macro-porosity from that
which would be expected from a given taxonomic type.Comment: Accepted for publication in MNRA
- …