Does the 3D Feature Descriptor Impact The Registration Accuracy in Laparoscopic Liver Surgery?

In laparoscopic liver surgery (LLS) image-guidednavigation systems could support the surgeon by providingsubsurface information such as the positions of tumors andvessels. For this purpose, one option is to perform a registra-tion of preoperative 3D data and 3D surface patches recon-structed from laparoscopic images. Part of an automatic 3Dregistration pipeline is the feature description, which takes intoaccount various geometric and spatial information. Since thereis no leading feature descriptor in the field of LLS, two featuredescriptors are compared in this paper: The Fast Point FeatureHistogram (FPFH) and Triple Orthogonal Local Depth Images(TOLDI). To evaluate their performance, three perturbationswere induced: varying surface patch sizes, spatial displace-ment, and Gaussian deformation. Registration was performedusing the RANSAC algorithm. FPFH outperformed TOLDIfor small surface patches and in case of Gaussian deformationsin terms of registration accuracy. In contrast, TOLDI showedlower registration errors for patches with spatial displacement.While developing a 3D-3D registration pipeline, the choice ofthe feature descriptor is of importance, consequently a carefulchoice suitable for the application in LLS is necessary

A Statistical Shape Model Pipeline to Enable the Creation of Synthetic 3D Liver Data

The application of machine learning approaches in medical technology is gaining more and more attention. Due to the high restrictions for collecting intraoperative patient data, synthetic data is increasingly used to support the training of artificial neural networks. We present a pipeline to create a statistical shape model (SSM) using 28 segmented clinical liver CT scans. Our pipeline consists of four steps: data preprocessing, rigid alignment, template morphing, and statistical modeling. We compared two different template morphing approaches: Laplace-Beltrami-regularized projection (LBRP) and nonrigid iterative closest points translational (N-ICP-T) and evaluated both morphing approaches and their corresponding shape model performance using six metrics. LBRP achieved a smaller mean vertex-to-nearest-neighbor distances (2.486 ± 0.897 mm) than N-ICP-T (5.559 ± 2.413 mm). Generalization and specificity errors for LBRP were consistently lower than those of N-ICP-T. The first principal components of the SSM showed realistic anatomical ariations. The performance of the SSM was comparable to a state-of-the-art model

Surface recombination measurements on III–V candidate materials for nanostructure light-emitting diodes

Surface recombination is an important characteristic of an optoelectronic material. Although surface recombination is a limiting factor for very small devices it has not been studied intensively. We have investigated surface recombination velocity on the exposed surfaces of the AlGaN, InGaAs, and InGaAlP material systems by using absolute photoluminescence quantum efficiency measurements. Two of these three material systems have low enough surface recombination velocity to be usable in nanoscale photonic crystal light-emitting diodes

Identificação e caracterização dos depósitos de várzea no trecho fluvial da Volta Grande, Rio Uruguai - SC/RS

The study of the sedimentary records of surface coverings has great importance for understanding the past and present processes that shaped the landscape, since it is a valuable instrument for interpreting and understanding the processes and changes that a particular landscape has undergone during the last few thousand years. From the point of view of the fluvial environment, the recognition of the width and morphology of the alluvial plain of a river brings important contributions to understand these changes and the sedimentary record that configures the different superficial coverings within the fluvial valley. Therefore, this work aims to analyze the morphology and sediments along the banks of the stretch of the Uruguay River known as Volta Grande on the border between Santa Catarina and Rio Grande do Sul. This perspective is tied to the approach of the interrelations between the River and river environments as a basis for the integrated understanding of the evolution of the landscape in this stretch of the Uruguay River valley in western Santa Catarina. The preliminary delimitation of the floodplain of the Uruguay River was made and contrasted these limits with the results of the field observations and the particle size analysis of samples collected along the Uruguay River as a means of verifying the fluvial participation in the configuration of these sedimentary deposits Of low slope. Thus verifying that prevailing materials predominantly of textural class, argilo siltosa and clayey / very clayey, in a great process of weathering.O estudo dos registros sedimentares das coberturas superficiais possui grande importância para a compreensão dos processos pretéritos e atuais que moldaram a paisagem. Esses registros são valiosos instrumentos para interpretar e compreender os processos e as mudanças pelas quais a paisagem passou durante os últimos milhares de anos. Do ponto de vista do ambiente fluvial, o reconhecimento da largura, da morfologia e dos depósitos da planície aluvial de um rio traz contribuições importantes para compreender essas mudanças e o registro sedimentar que configura as diferentes coberturas superficiais dentro do vale fluvial. Este trabalho delimitou e analisou alguns materiais da várzea do rio Uruguai no trecho conhecido como Volta Grande na divisa entre Santa Catarina e Rio Grande do Sul. A delimitação prévia da planície de inundação da Volta Grande foi feita com base em imagens de satélite por meio do software Google Earth Pro. Em trabalho de campo esses limites foram contrapostos às observações de campo e posteriormente readequados. Foram coletadas em campo, nos trechos tipicamente caracterizados como várzea, amostras de sedimentos para análise granulométrica como meio de verificar a participação fluvial na configuração desses depósitos sedimentares de baixa vertente. Os resultados mostraram que a várzea no trecho fluvial da Volta Grande apresenta-se de modo descontínuo, ora com trechos mais largos, ora com trechos muito estreitos ou mesmo inexistentes, dada a proximidade do leito de encostas íngremes sustentadas por rocha basáltica. As análises granulométricas demonstraram materiais predominantemente de classe textural franco argilo siltosa e argilosa/muito argilosa

The use of media in language teaching

Multilingual teaching and the promotion of multilingualism among students are important principles of the University of Luxembourg. For their implementation, a variety of e-learning resources are used, adapted to the needs of the learners. We will give an overview of new multimodal communication practices and methods used by learners in multilingual contexts which naturally lead teachers to rethink their approach and incorporate media into their teaching strategies. The hybrid nature of devices (computers, tablets, televisions, smartphones, paper, interactive whiteboards, etc.) and digital tools (document sharing platforms, online correction tools, interactive exercises, online learning programmes, dictionaries, video editing software, automatic pronunciation correction, etc.) offer a great potential to interactive and mobile teaching and learning. We will illustrate this potential by giving an example of how to develop text production competence in Chinese as a foreign language in a motivating way using the content management system Moodle. Our reflection aims at optimising the quality of language teaching both in and out of the classroom

Twinning superlattices in indium phosphide nanowires

Here, we show that we control the crystal structure of indium phosphide (InP) nanowires by impurity dopants. We have found that zinc decreases the activation barrier for 2D nucleation growth of zinc-blende InP and therefore promotes the InP nanowires to crystallise in the zinc blende, instead of the commonly found wurtzite crystal structure. More importantly, we demonstrate that we can, by controlling the crystal structure, induce twinning superlattices with long-range order in InP nanowires. We can tune the spacing of the superlattices by the wire diameter and the zinc concentration and present a model based on the cross-sectional shape of the zinc-blende InP nanowires to quantitatively explain the formation of the periodic twinning.Comment: 18 pages, 4 figure

Generation of a Simplified Brain Geometry for the Calculation of Local Cerebral Temperature using a 1D Hemodynamic Model

In Western countries, stroke is the third-most cause of death; 35– 55% of the survivors experience permanent disability. Mild therapeutic hypothermia (TH) showed neuroprotective effect in patients returning from cardiac arrest and is therefore assumed to decrease stroke induced cerebral damage. Recently, an intracarotid cooling sheath was developed to induce local TH in the penumbra using the cooling effect of cerebral blood flow via collaterals. Computational modeling provides unique opportunities to predict the resulting cerebral temperature without invasive procedures. In this work, we generated a simplified brain model to establish a cerebral temperature calculation using Pennes’ bio-heat equation and a 1D hemodynamics model of the cranial artery tree. In this context, we performed an extensive literature research to assign the terminal segments of the latter to the corresponding perfused tissue. Using the intracarotid cooling method, we simulated the treatment with TH for different degrees of stenosis in the middle cerebral artery (MCA) and analyzed the resulting temperature spatialtemporal distributions of the brain and the systemic body considering the influence of the collaterals on the effect of cooling

Recurrent Cellulitis Associated with Long-Term Intrathecal Opioid Infusion Therapy: A Case Report and Review of the Literature

Lower-limb edema is recognized as an untoward side effect of intrathecal opioid therapy. Cellulitis, an acute, spreading pyogenic inflammation of the dermis and subcutaneous tissue, predisposed by persistent leg edema, can become problematic in patients on intraspinal opioid infusion therapy.To present a case of recurrent cellulitis in an elderly lady with persistent leg edema associated with intrathecal morphine/hydromorphone infusion therapy.Sixty-one-year-old woman with intractable chronic low back pain and bilateral leg pain treated with an intrathecal infusion of morphine up to 5 mg/day over 3 months with satisfactory pain control developed progressive lower extremity edema, complicated by recurrent cellulitis, requiring repeated hospitalization and intravenous antibiotic treatment. Switching to intrathecal hydromorphone helped minimally. Intrathecal baclofen and clonidine infusion resulted in complete resolution of leg edema and pain relief over the following 12 months.Intrathecal Baclofen and Clonidine may be used as alternatives to provide spinally mediated antinociception when intraspinal opioid fails due to pharmacological side effects such as persistent edema.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79174/1/j.1526-4637.2010.00854.x.pd

Influences of excitation-dependent bandstructure changes on InGaN light-emitting diode efficiency

Bandstructure properties in wurtzite quantum wells can change appreciably with changing carrier density because of screening of quantum-confined Stark effect. An approach for incorporating these changes in an InGaN light-emitting-diode model is described. Bandstructure is computed for different carrier densities by solving Poisson and k\cdotp equations in the envelop approximation. The information is used as input in a dynamical model for populations in momentum-resolved electron and hole states. Application of the approach is illustrated by modeling device internal quantum efficiency as a function of excitation

Effects of near-infrared light on well-being and health in human subjects with mild sleep-related complaints:A double-blind, randomized, placebo-controlled study

Modern urban human activities are largely restricted to the indoors, deprived of direct sunlight containing visible and near-infrared (NIR) wavelengths at high irradiance levels. Therapeutic exposure to doses of red and NIR, known as photobiomodulation (PBM), has been effective for a broad range of conditions. In a double-blind, randomized, placebo-controlled study, we aimed to assess the effects of a PBM home set-up on various aspects of well-being, health, sleep, and circadian rhythms in healthy human subjects with mild sleep complaints. The effects of three NIR light (850 nm) doses (1, 4, or 6.5 J·cm−2) were examined against the placebo. Exposure was presented five days per week between 9:30 am and 12:30 pm for four consecutive weeks. The study was conducted in both summer and winter to include seasonal variation. The results showed PBM treatment only at 6.5 J·cm−2 to have consistent positive benefits on well-being and health, specifically improving mood, reducing drowsiness, reducing IFN-γ, and resting heart rate. This was only observed in winter. No significant effects on sleep or circadian rhythms were noted. This study provides further evidence that adequate exposure to NIR, especially during low sunlight conditions, such as in the winter, can be beneficial for human health and wellness.</p