Denoising and enhancement of mammographic images under the assumption of heteroscedastic additive noise by an optimal subband thresholding

Mammographic images suffer from low contrast and signal dependent noise, and a very small size of tumoral signs is not easily detected, especially for an early diagnosis of breast cancer. In this context, many methods proposed in literature fail for lack of generality. In particular, too weak assumptions on the noise model, e.g., stationary normal additive noise, and an inaccurate choice of the wavelet family that is applied, can lead to an information loss, noise emphasizing, unacceptable enhancement results, or in turn an unwanted distortion of the original image aspect. In this paper, we consider an optimal wavelet thresholding, in the context of Discrete Dyadic Wavelet Transforms, by directly relating all the parameters involved in both denoising and contrast enhancement to signal dependent noise variance (estimated by a robust algorithm) and to the size of cancer signs. Moreover, by performing a reconstruction from a zero-approximation in conjunction with a Gaussian smoothing filter, we are able to extract the background and the foreground of the image separately, as to compute suitable contrast improvement indexes. The whole procedure will be tested on high resolution X-ray mammographic images and compared with other techniques. Anyway, the visual assessment of the results by an expert radiologist will be also considered as a subjective evaluation

Order-of-magnitude speedup for steady states and traveling waves via Stokes preconditioning in Channelflow and Openpipeflow

Steady states and traveling waves play a fundamental role in understanding hydrodynamic problems. Even when unstable, these states provide the bifurcation-theoretic explanation for the origin of the observed states. In turbulent wall-bounded shear flows, these states have been hypothesized to be saddle points organizing the trajectories within a chaotic attractor. These states must be computed with Newton's method or one of its generalizations, since time-integration cannot converge to unstable equilibria. The bottleneck is the solution of linear systems involving the Jacobian of the Navier-Stokes or Boussinesq equations. Originally such computations were carried out by constructing and directly inverting the Jacobian, but this is unfeasible for the matrices arising from three-dimensional hydrodynamic configurations in large domains. A popular method is to seek states that are invariant under numerical time integration. Surprisingly, equilibria may also be found by seeking flows that are invariant under a single very large Backwards-Euler Forwards-Euler timestep. We show that this method, called Stokes preconditioning, is 10 to 50 times faster at computing steady states in plane Couette flow and traveling waves in pipe flow. Moreover, it can be carried out using Channelflow (by Gibson) and Openpipeflow (by Willis) without any changes to these popular spectral codes. We explain the convergence rate as a function of the integration period and Reynolds number by computing the full spectra of the operators corresponding to the Jacobians of both methods.Comment: in Computational Modelling of Bifurcations and Instabilities in Fluid Dynamics, ed. Alexander Gelfgat (Springer, 2018

Subpopulations of anti-β2glycoprotein I antibodies with different pathogenic potential: fine specificity against the domains of β2glycoprotein I

Objective: Anti-β2glycoprotein I antibodies (a-β2GPI) are a laboratory criterion for the antiphospholipid syndrome (APS) and were demonstrated to be involved in the pathogenesis of APS. However, they can also be detected in asymptomatic subjects. It has been suggested that a-β2GPI against Domain1 (D1) associate with thrombosis, while those recognizing Domain4/5 (D4/5) have been identified in non-thrombotic conditions. We evaluate the specificity of a- β2GPI in different clinical situations. Methods: We studied 39 one-year-old healthy children born to mothers with systemic autoimmune diseases (SAD) (15 (38.4%) were born to mothers who were a-β2GPI positive), 33 children with atopic dermatitis (AD) and 55 patients with APS (50 adults and 5 paediatrics). All subjects were IgG a-β2GPI positive. IgG a-β2GPI were performed by homemade ELISA, while IgG a-β2GPI D1 and D4/5 were tested on research ELISAs containing recombinant β2GPI domains antigens. Results: One-year-old children and AD children displayed preferential reactivity for D4/5; patients with APS recognized preferentially D1. We also found a good correlation between a-β2GPI and D4/5 in one-year-old (r=0.853) and AD children (r=0.879) and between a-β2GPI and D1 in the APS group (r=0.575). No thrombotic events were recorded in both groups of children. Conclusions: A-β2GPI found in non-thrombotic conditions (healthy children born to mothers with SAD and AD children) mostly recognize D4/5, in contrast to the prevalent specificity for D1 in the APS group. The different specificity could at least partially explain the "innocent" profile of a-β2GPI in children

Neuromotor Changes in Participants with a Concussion History can be Detected with a Custom Smartphone App

Neuromotor dysfunction after a concussion is common, but balance tests used to assess neuromotor dysfunction are typically subjective. Current objective balance tests are either cost- or space-prohibitive, or utilize a static balance protocol, which may mask neuromotor dysfunction due to the simplicity of the task. To address this gap, our team developed an Android-based smartphone app (portable and cost-effective) that uses the sensors in the device (objective) to record movement profiles during a stepping-in-place task (dynamic movement). The purpose of this study was to examine the extent to which our custom smartphone app and protocol could discriminate neuromotor behavior between concussed and non-concussed participants. Data were collected at two university laboratories and two military sites. Participants included civilians and Service Members (N = 216) with and without a clinically diagnosed concussion. Kinematic and variability metrics were derived from a thigh angle time series while the participants completed a series of stepping-in-place tasks in three conditions: eyes open, eyes closed, and head shake. We observed that the standard deviation of the mean maximum angular velocity of the thigh was higher in the participants with a concussion history in the eyes closed and head shake conditions of the stepping-in-place task. Consistent with the optimal movement variability hypothesis, we showed that increased movement variability occurs in participants with a concussion history, for which our smartphone app and protocol were sensitive enough to capture

Acute cardiac injury after subarachnoid haemorrhage: two case reports

It is well known that cardiopulmonary complications are often associated to subarachnoid haemorrhage. For appropriate therapeutic managing it is very important to distinguish acute coronary syndrome from neurogenic myocardial injury, which is a reversible condition. Furthermore, because the hearts of brain dead patients may be utilized for therapeutic purpose, it has became of importance to rule out erroneous diagnosis of cardiac ischemia in order to avoid rejection of hearts potential suitable for transplantation

2D dosimeter based on monolithic silicon sensors for beam verification in conformal radiotherapy

Due to the features of modern radiotherapy techniques, such as Intensity Modulated Radiation Therapy (IMRT), Stereotactic Treatments with photons and proton therapy, where high spatial dose gradient are often present, detectors to be employed for two-dimensional dose verifications must satisfy narrow requirements. In particular, they have to exhibit high spatial resolution. For these applications, in the framework of the European Integrated project MAESTRO (LSHC-CT-2004-503564) and of the INFN experiment PRIMA, we designed a modular system based on a monolithic silicon segmented sensor. A single sensor has been coupled with readout electronics and tested with satisfactory results by using 6, 10 and 25MV X-rays from a LINAC at the University Hospital of Florence and 62MeV protons at INFN LNS Catania, following MAESTRO procedures. For photons, almost all the channels exhibit performances within project specifications (repeatability ≪0.5%, reproducibility ≪1%, deviation from linearity ≪1%, dose rate dependence ≪1%). For protons, the measured Spread Out Bragg Peak is in good agreement with the one measured with a single diode and the detector shows also a good linearity in the range 20–5000 cGy. The output factors are in agreement with those measured with ionization chamber, single diode or film, within experimental errors