An image-based approach to interactive crease extraction and rendering

AbstractRidge and valley manifolds are receiving a growing attention in visualization research due to their ability to reveal the shapes of salient structures in numerical datasets across scientific, engineering, and medical applications. However, the methods proposed to date for their extraction in the visualization and image analysis literature are computationally expensive and typically applied in an offline setting. This setup does not properly support a userdriven exploration, which often requires control over various parameters tuned to filter false positives and spurious artifacts and highlight the most significant structures. This paper presents a GPU-based adaptive technique for crease extraction and visualization across scales. Our method combines a scale-space analysis of the data in pre-processing with a ray casting approach supporting a robust and efficient one-dimensional numerical search, and an image-based rendering strategy. This general framework achieves high-quality crease surface representations at interactive frame rates. Results are proposed for analytical, medical, and computational datasets

Influence of local and remote white matter conductivity anisotropy for a thalamic source on EEG/MEG field and return current computation

nverse methods are used to reconstruct current sources in the human brain by means of Electroencephalogra- phy (EEG) and Magnetoencephalography (MEG) measure- ments of event related fields or epileptic seizures. There exists a persistent uncertainty regarding the influence of anisotropy of the white matter compartment on neural source reconstruc- tion. In this paper, we study the sensitivity to anisotropy of the EEG/MEG forward problem for a thalamic source in a high resolution finite element volume conductor. The influence of anisotropy on computed fields will be presented by both high resolution visualization of fields and return current flow and topography and magnitude error measures. We pay particular attention to the influence of local conductivity changes in the neighborhood of the source. The combination of simulation and visualization provides deep insight into the effect of white matter conductivity anisotropy. We found that for both EEG and MEG formulations, the local presence of electrical anisotropy in the tissue surroun- ding the source substantially compromised the forward field computation, and correspondingly, the inverse source recons- truction. The degree of error resulting from the uncompen- sated presence of tissue anisotropy depended strongly on the proximity of the anisotropy to the source; remote anisotropy had a much weaker influence than anisotropic tissue that included the source

Nitrous oxide does not produce a clinically important sparing effect during closed-loop delivered propofol-remifentanil anaesthesia guided by the bispectral index: a randomized multicentre study†‡

Background Nitrous oxide (N2O) offers both hypnotic and analgesic characteristics. We therefore tested the hypothesis that N2O administration decreases the amount of propofol and remifentanil given by a closed-loop automated controller to maintain a similar bispectral index (BIS). Methods In a randomized multicentre double-blind study, patients undergoing elective surgery were randomly assigned to breathe 60% inspired N2O (N2O group) or 40% oxygen (AIR group). Anaesthesia depth was evaluated by the proportion of time where BIS was within the range of 40-60 (BIS40-60). The primary outcomes were propofol and remifentanil consumption, with reductions of 20% in either being considered clinically important. Results A total of 302 patients were randomized to the N2O group and 299 to the AIR group. At similar BIS40-60 [79 (67-86)% vs 76 (65-85)%], N2O slightly decreased propofol consumption [4.5 (3.7-5.5) vs 4.8 (4.0-5.9) mg kg−1 h−1, P=0.032], but not remifentanil consumption [0.17 (0.12-0.23) vs 0.18 (0.14-0.24) µg kg−1 min−1]. For the subgroups of men, at similar BIS40-60 [80 (72-88)% vs 80 (70-87)%], propofol [4.2 (3.4-5.3) vs 4.4 (3.6-5.4) mg kg−1 h−1] and remifentanil [0.19 (0.13-0.25) vs 0.18 (0.15-0.23) µg kg−1 min−1] consumptions were similar in the N2O vs AIR group, respectively. For the subgroups of women, at similar BIS40-60 [76 (64-84)% vs 72 (62-82)%], propofol [4.7 (4.0-5.8) vs 5.3 (4.5-6.6) mg kg−1 h−1, P=0.004] and remifentanil [0.18 (0.13-0.25) vs 0.20 (0.15-0.27) µg kg−1 min−1, P=0.029] consumptions decreased with the co-administration of N2O. Conclusions With automated drug administration titrated to comparable BIS, N2O only slightly reduced propofol consumption and did not reduce remifentanil consumption. There was a minor gender dependence, but not by a clinically important amount. Clinical trial registration This study was registered at ClinicalTrials.gov, number NCT0054720

The Adjuvanticity of an O. volvulus-Derived rOv-ASP-1 Protein in Mice Using Sequential Vaccinations and in Non-Human Primates

Adjuvants potentiate antigen-specific protective immune responses and can be key elements promoting vaccine effectiveness. We previously reported that the Onchocerca volvulus recombinant protein rOv-ASP-1 can induce activation and maturation of naïve human DCs and therefore could be used as an innate adjuvant to promote balanced Th1 and Th2 responses to bystander vaccine antigens in mice. With a few vaccine antigens, it also promoted a Th1-biased response based on pronounced induction of Th1-associated IgG2a and IgG2b antibody responses and the upregulated production of Th1 cytokines, including IL-2, IFN-γ, TNF-α and IL-6. However, because it is a protein, the rOv-ASP-1 adjuvant may also induce anti-self-antibodies. Therefore, it was important to verify that the host responses to self will not affect the adjuvanticity of rOv-ASP-1 when it is used in subsequent vaccinations with the same or different vaccine antigens. In this study, we have established rOv-ASP-1's adjuvanticity in mice during the course of two sequential vaccinations using two vaccine model systems: the receptor-binding domain (RBD) of SARS-CoV spike protein and a commercial influenza virus hemagglutinin (HA) vaccine comprised of three virus strains. Moreover, the adjuvanticity of rOv-ASP-1 was retained with an efficacy similar to that obtained when it was used for a first vaccination, even though a high level of anti-rOv-ASP-1 antibodies was present in the sera of mice before the administration of the second vaccine. To further demonstrate its utility as an adjuvant for human use, we also immunized non-human primates (NHPs) with RBD plus rOv-ASP-1 and showed that rOv-ASP-1 could induce high titres of functional and protective anti-RBD antibody responses in NHPs. Notably, the rOv-ASP-1 adjuvant did not induce high titer antibodies against self in NHPs. Thus, the present study provided a sound scientific foundation for future strategies in the development of this novel protein adjuvant

Microstructure design of lead-free piezoelectric ceramics

Computational and experimental methodologies are integrated into a novel combined technique to define microstructure design criteria and maximize the properties of rhombohedral Bi 0.5Na 0.4K 0.1TiO 3, from untextured (1 MRD), d 33 = 155pC/N, to textured (4.41 MRDs), d 33 = 227pC/N. Two-dimensional orientation maps obtained using electron backscatter diffraction on sequential parallel layers are used to computationally reconstruct three-dimensional samples, simulate the local piezoelectric grain interactions, and thus demonstrate that superior lead-free piezoelectric microstructures can be fabricated by engineering its associated crystallographic and polarization texture. Computer-generated material representations, based on the experimentally determined microstructures, were used to simulate the crystallographic orientation of each grain, as function a macroscopic polarization and crystallographic texture. Computer-generated material representations, based on the experimentally determined microstructures, were used to simulate the crystallographic orientation of each grain, as function a macroscopic polarization and crystallographic texture. The method takes advantage of the anisotropy of the properties of the underlying single-crystal phases and delivers a guide to search for material anisotropy |microstructure parameters that are optimal in piezoelectric performance and reliability, and thus establish practical links between structure and macroscopic length scales.close6