Gradient-based 2-D/3-D rigid registration of fluoroscopic X-ray to CT

We present a gradient-based method for rigid registration of a patient preoperative computed tomography (CT) to its intraoperative situation with a few fluoroscopic X-ray images obtained with a tracked C-arm. The method is noninvasive, anatomy-based, requires simple user interaction, and includes validation. It is generic and easily customizable for a variety of routine clinical uses in orthopaedic surgery. Gradient-based registration consists of three steps: 1) initial pose estimation; 2) coarse geometry-based registration on bone contours, and; 3) fine gradient projection registration (GPR) on edge pixels. It optimizes speed, accuracy, and robustness. Its novelty resides in using volume gradients to eliminate outliers and foreign objects in the fluoroscopic X-ray images, in speeding up computation, and in achieving higher accuracy. It overcomes the drawbacks of intensity-based methods, which are slow and have a limited convergence range, and of geometry-based methods, which depend on the image segmentation quality. Our simulated, in vitro, and cadaver experiments on a human pelvis CT, dry vertebra, dry femur, fresh lamb hip, and human pelvis under realistic conditions show a mean 0.5-1.7 mm (0.5-2.6 mm maximum) target registration accuracy.     

RNA-binding protein conserved in both microtubule- and microfilament-based RNA localization

IL-12 is a key cytokine in the development of Th1 responses. IL-12 production by antigen-presenting cells (APC) can be induced by the interaction between CD40 on the APC and CD40 ligand (CD40L) expressed on T cells after activation. Our previous study indicated that in dendritic cells (DC), the only APC that can activate naive T(h) cells efficiently, the mere CD40 engagement is insufficient to induce IL-12 production. The aim of the present study was to dissect the conditions for efficient IL-12 production by DC further. Using populations of naive and memory Th cells, recombinant CD40L, neutralizing and blocking antibodies, and by determining IFN-gamma production and CD40L expression levels, we here show that T cell-induced IL-12 production by DC results from the action of two signals, mediated by CD40L and IFN-gamma, and that the inability of naive T(h) cells to induce IL-12 production resides in their inability to produce IFN-(gamma). Other factors than CD40L and IFN-gamma can provide the required signals for IL-12 production by DC, as either factor could be replaced by lipopolysaccharide (LPS). The two-signal requirement proved unique for the production of IL-12, since either CD40 engagement or LPS was sufficient for the efficient production of tumor necrosis factor-alpha, IL-8 and the p40 subunit of IL-12, and may be considered as a safety mechanism for optimal control of potentially harmful T(h)1 responses.     

Constant-Power Bit Loading for Multicarrier Systems: BER-Allocation

Adaptive bit loading algorithms are proposed for multi-channel systems in general, and orthogonal frequency division multiplexing in particular. A discrete coding-modulation adaptation is considered. Constant power allocation is assumed for all subchannels, while the bit error rate on different subchannels is unconstrained. The proposed algorithms are computationally efficient and require limited amount of feedback resources. Their performance compare favorably with other practical schemes known in the art.     

Fast direct solution of 3-D scattering problems via nonuniform grid-based matrix compression

A fast non-iterative algorithm for the solution of large 3-D acoustic scattering problems is presented. The proposed approach can be used in conjunction with the conventional boundary element discretization of the integral equations of acoustic scattering. The algorithm involves domain decomposition and uses the nonuniform grid (NG) approach for the initial compression of the interactions between each subdomain and the rest of the scatterer. These interactions, represented by the off-diagonal blocks of the boundary element method matrix, are then further compressed while constructing sets of interacting and local basis and testing functions. The compressed matrix is obtained by eliminating the local degrees of freedom through the Schur's complement-based technique procedure applied to the diagonal blocks. In the solution process, the interacting unknowns are first determined by solving the compressed system equations. Subsequently, the local degrees of freedom are determined for each subdomain. The proposed technique effectively reduces the oversampling typically needed when using low-order discretization techniques and provides significant computational savings.     

An electrical equivalent for barrier anodic films on aluminium

A duplex-film model for barrier anodic films on aluminium is suggested, the lower layer being homogeneous and amorphous and the upper consisting of a dispersion of a crystalline phase in an amorphous matrix. From impedance measurements over a range of frequencies, the dielectric constants of the layers are estimated as 12 and 9 respectively.     

Stress-activated protein kinases are negatively regulated by cell density

Stimulation by UV irradiation, TNFalpha, as well as PDGF or EGF activates the JNK/SAPK signalling pathway in mouse fibroblasts. This results in the phosphorylation of the N-terminal domain of c-Jun, increasing its transactivation potency. Using an antibody that specifically recognizes c-Jun phosphorylated at Ser63, we show that culture confluency drastically inhibited c-Jun N-terminal phosphorylation due to the inhibition of the JNK/SAPK pathway. Transfection experiments demonstrate that the inhibition occurs at the same level as, or upstream of, the small G-proteins cdc42 and Rac1. In contrast, the classical MAPK pathway was insensitive to confluency. The inhibition of JNK/SAPK activation depended on the integrity of the actin microfilament network. These results were confirmed and extended in monolayer wounding experiments. After PDGF, EGF or UV stimulation, c-Jun was predominantly phosphorylated in cells bordering the wound, which are the cells that move to occupy the wounded area. Thus, modulation of the stress-dependent signal cascade by confluency will restrict c-Jun N-terminal phosphorylation in response to mitogenic or chemotactic agents to cells that border a wounded area.     

Multi-input/single-output computer-aided control design using the quantitative feedback theory

The quantitative feedback theory is an engineering design technique of uncertain feedback systems having robust stability and robust performance specifications. The crux of the quantitative feedback theory is a transformation of robust stability and robust performance specifications into domains in the complex plane, referred to as bounds, where a nominal loop transmission should lie within. To date, a quantitative feedback theory design is being carried out using manual (i.e. graphical) procedures or search algorithms. This paper shows that there exists a formal map from the uncertain plant and each closed-loop specification to these bounds. In particular, it is shown that each map has a closed form consisting of a quadratic inequality. These maps greatly simplify the computational aspects of the quantitative feedback theory in design of single-loop feedback systems. Based on this new development, a simple-to-implement, efficient computer algorithm is outlined.     

Concurrent Java Test Generation as a Search Problem

A Random test generator generates executable tests together with their expected results. In the form of a noise-maker, it seeds the program with conditional scheduling primitives (such as yield()) that may cause context switches. As a result different interleavings are potentially produced in different executions of the program. Determining a-priori the set of seeded locations required for a bug to manifest itself is rarely possible.This work proposes to reformulate random test generation of concurrent Java programs as a search problem. Hence, it allows applying a set of well known search techniques from the domain of AI to the input space of the test generator. By iteratively refining the input parameters fed to the test generator, the search process creates testing scenarios (i.e. interleavings) that maximizes predefined objective functions. We develop geneticFinder, a noise-maker that uses a genetic algorithm as a search method. We demonstrate our approach by maximizing two objective functions: the high manifestation rate of concurrent bugs and the exporting of a high degree of debugging information to the user. Experimental results show our approach is effective.     

RADE: resource-efficient supervised anomaly detection using decision tree-based ensemble methods

Machine Learning - The capability to perform anomaly detection in a resource-constrained setting, such as an edge device or a loaded server, is of increasing need due to emerging on-premises...