Stochastic Block Models with Multiple Continuous Attributes

The stochastic block model (SBM) is a probabilistic model for community structure in networks. Typically, only the adjacency matrix is used to perform SBM parameter inference. In this paper, we consider circumstances in which nodes have an associated vector of continuous attributes that are also used to learn the node-to-community assignments and corresponding SBM parameters. While this assumption is not realistic for every application, our model assumes that the attributes associated with the nodes in a network's community can be described by a common multivariate Gaussian model. In this augmented, attributed SBM, the objective is to simultaneously learn the SBM connectivity probabilities with the multivariate Gaussian parameters describing each community. While there are recent examples in the literature that combine connectivity and attribute information to inform community detection, our model is the first augmented stochastic block model to handle multiple continuous attributes. This provides the flexibility in biological data to, for example, augment connectivity information with continuous measurements from multiple experimental modalities. Because the lack of labeled network data often makes community detection results difficult to validate, we highlight the usefulness of our model for two network prediction tasks: link prediction and collaborative filtering. As a result of fitting this attributed stochastic block model, one can predict the attribute vector or connectivity patterns for a new node in the event of the complementary source of information (connectivity or attributes, respectively). We also highlight two biological examples where the attributed stochastic block model provides satisfactory performance in the link prediction and collaborative filtering tasks

The Incidence and Clinical Relevance of Graft Hypertrophy After Matrix-Based Autologous Chondrocyte Implantation

Background: Graft hypertrophy is the most common complication of periosteal autologous chondrocyte implantation (p-ACI). Purpose: The aim of this prospective study was to analyze the development, the incidence rate, and the persistence of graft hypertrophy after matrix-based autologous chondrocyte implantation (mb-ACI) in the knee joint within a 2-year postoperative course. Study Design: Case series; Level of evidence, 4. Methods: Between 2004 and 2007, a total of 41 patients with 44 isolated cartilage defects of the knee were treated with the mb-ACI technique. The mean age of the patients was 35.8 years (standard deviation [SD], 11.3 years), and the mean body mass index was 25.9 (SD, 4.2; range, 19-35.3). The cartilage defects were arthroscopically classified as Outerbridge grades III and IV. The mean area of the cartilage defect measured 6.14 cm2 (SD, 2.3 cm2). Postoperative clinical and magnetic resonance imaging (MRI) examinations were conducted at 3, 6, 12, and 24 months to analyze the incidence and course of the graft. Results: Graft hypertrophy developed in 25% of the patients treated with mb-ACI within a postoperative course of 1 year; 16% of the patients developed hypertrophy grade 2, and 9% developed hypertrophy grade 1. Graft hypertrophy occurred primarily in the first 12 months and regressed in most cases within 2 years. The International Knee Documentation Committee (IKDC) and visual analog scale (VAS) scores improved during the postoperative follow-up time of 2 years. There was no difference between the clinical results regarding the IKDC and VAS pain scores and the presence of graft hypertrophy. Conclusion: The mb-ACI technique does not lead to graft hypertrophy requiring treatment as opposed to classic p-ACI. The frequency of occurrence of graft hypertrophy after p-ACI and mb-ACI is comparable. Graft hypertrophy can be considered as a temporary excessive growth of regenerative cartilage tissue rather than a true graft hypertrophy. It is therefore usually not a persistent or systematic complication in the treatment of circumscribed cartilage defects with mb-ACI

Investigations on Spark and Corona Ignition of Oxymethylene Ether-1 and Dimethyl Carbonate Blends with Gasoline by High-Speed Evaluation of OH* Chemiluminescence

Bio-fuels of the 2nd generation constitute a key approach to tackle both Greenhouse Gas (GHG) and air quality challenges associated with combustion emissions of the transport sector. Since these fuels are obtained of residual materials of the agricultural industry, well-totank CO2 emissions can be significantly lowered by a closed-cycle of formation and absorption of CO2. Furthermore, studies of bio-fuels have shown reduced formation of particulate matter on account of the fuels’ high oxygen content therefore addressing air quality issues. However, due to the high oxygen content and other physical parameters these fuels are expected to exhibit different ignition behaviour. Moreover, the question is whether there is a positive superimposition of the fuels ignition behaviour with the benefits of an alternative ignition system, such as a corona ignition. To shed light on these questions two oxygenic compounds, oxymethylene ether-1 (OME1) and dimethyl carbonate (DMC) have been studied with respect to OH* emission throughout ignition and onset of flame-front propagation in a combustion chamber with a large optical access via a quartz window. OH* measurements have been recorded via a highspeed optical camera (5 kHz) coupled with 308 nm optical filter and image intensifier. Sealing material swelling tests have yielded a perfluoroelastomer (FFKM 72) as an ideal, cost-efficient material regardless of the applied fuel. Comparative measurements with both ignition systems for combustion of gasoline as well as moderate blend admixtures of OME1 and DMC have demonstrated the superior ignition stability with likewise implications on flame-kernel development for the corona ignition. Furthermore a strong influence of the mode of discharge on OH* formation rates was observed especially for the oxygenic blends. Finally, for admixture variations of both oxygenates, an increased OH* level was shown during discharge thereby proving the hypothesis of a positive superimposition of oxygenic fuel and corona ignition system

Gasoline from the bioliq® process: Production, characterization and performance

Within the so-called bioliq® process, renewable carbon resources, especially agricultural residues, are converted to gasoline. The process chain comprises pyrolysis of the feedstocks, gasification to synthesis gas, gas cleaning and conversion of synthesis gas to dimethyl ether (DME) followed by conversion of DME to hydrocarbons. Construction of all process units has been completed now and the entire plant has been successfully operated in several campaigns. Thus, hundreds of liters of a new alternative gasoline are available now, which allow for an extensive testing. The basic characteristics of the resulting bioliq®/100 fuel are described. It is rich in aromatics and a blend consisting of 90 Vol.−% of conventional RON95 E5 fuel and 10 Vol.−% of bioliq®/100, designated as bioliq®/10, has been produced which meets the DIN EN 228 standard. Initial measurements on a single cylinder research engine have been carried out focusing on efficiency and emissions. A comparison of bioliq®/10 with neat RON95 E5 revealed an improved knocking behavior of bioliq®/10 even by a small fraction of regenerative bioliq® fuel. Particle as well as hydrocarbon emissions from bioliq®/10 are significantly higher than in the case of RON95 E5. Increased particle emissions are attributed to the higher content of aromatics. Soot reactivity has been investigated and soot from bioliq®/10 exhibits higher reactivity than soot from RON95 E5

Third generation autologous chondrocyte implantation is a good treatment option for athletic persons

PURPOSE Autologous chondrocyte implantation is an established method for the treatment of joint cartilage damage. However, to date it has not been established that autologous chondrocyte implantation is an appropriate procedure for cartilage defects therapy in athletic persons. The aim of this study is to analyze if third-generation autologous chondrocyte implantation is an appropriate treatment for athletic persons with full cartilage defect of the knee joints. METHODS A total of 84 patients were treated with third-generation autologous chondrocyte implantation (NOVOCART® 3D). The mean follow-up time was 8 years (5–14). Sports activity was measured via UCLA Activity Score and Tegner Activity Scale before the onset of knee pain and postoperatively in an annual clinical evaluation. 41 athletic persons and 43 non-athletic persons (UCLA-Cut-off: 7; Tegner Activity Scale-Cut-off: 4) were analyzed. Patient reported outcomes were captured using IKDC subjective, KOOS, Lysholm score and VAS score on movement. RESULTS Patient reported outcomes (IKDC, VAS at rest, VAS on movement) showed significant improvement (p < 0.001) postoperatively. Athletic persons demonstrated significantly better results than non-athletic persons in the analyzed outcome scores (IKDC: p < 0.01, KOOS: p < 0.01, Lysholm score: p < 0.01). 96.4% of the patients were able to return to sport and over 50% returned or surpassed their preinjury sports level. The remaining patients were downgraded by a median of two points on the UCLA- and 2.5 on the Tegner Activity Scale. A shift from high-impact sports to active events and moderate or mild activities was found. Furthermore, it was shown that preoperative UCLA score and Tegner Activity Scale correlated significantly with the patient reported outcome postoperatively. CONCLUSION Autologous chondrocyte implantation is a suitable treatment option for athletic persons with full-thickness cartilage defects in the knee. The return to sports activity is possible, but includes a shift from high-impact sports to less strenuous activities

Effect of the defect localization and size on the success of third-generation autologous chondrocyte implantation in the knee joint

Introduction. Femoral and patellar cartilage defects with a defect size > 2.5 cm2 are a potential indication for an autologous chondrocyte implantation (ACI). However, the influence of the localization and the absolute and relative defect size on the clinical outcome has not yet been determined. The purpose of this study is to analyze the influence of the localization and the absolute and relative defect size on the clinical outcome after third-generation autologous chondrocyte implantation. Methods. A total of 50 patients with cartilage defects of the knee were treated with third-generation autologous chondrocyte implantation (Novocart® 3D). A match paired analysis was performed of 25 treated femoral and 25 treated patella defects with a follow-up of three years. MRI data was used to do the manual segmentation of the cartilage layer throughout the knee joint. The defect size was determined by taking the defect size measured in the MRI in relation to the whole cartilage area. The clinical outcome was measured by the IKDC score and VAS pre-operatively and after six, 12, 24, and 36 months post-operatively. Results. IKDC and VAS scores showed a significant improvement from the baseline in both groups. Femoral cartilage defects showed significantly superior clinical results in the analyzed scores compared to patellar defects. The femoral group improved IKDC from 33.9 (SD 18.1) pre-operatively to 71.5 (SD 17.4) after three years and the VAS from 6.9 (SD 2.9) pre-operatively to 2.4 (SD 2.5) after three years. In the patellar group, IKDC improved from 36.1 (SD 12.6) pre-operatively to 54.7 (SD 20.3) after three years and the VAS improved from 6.7 (SD 2.8) pre-operatively to 3.4 (SD 2.) after three years. Regarding the defect size, results showed that the same absolute defect size at med FC (4.8, range 2–15) and patella (4.6, range 2–12) has a significantly different share of the total cartilaginous size of the joint compartment (med FC: 6.7, range 1.2–13.9; pat: 18.9, range 4.0–47.0). However, there was no significant influence of the relative defect size on the clinical outcome in either patellar or femoral localization. Conclusion. Third-generation autologous chondrocyte implantation in ACI-treated femoral cartilage defects leads to a superior clinical outcome in a follow-up of three years compared with patellar defects. No significant influence of the defect size was found in either femoral or patellar cartilage defects

Graft Hypertrophy After Third-Generation Autologous Chondrocyte Implantation Has No Correlation With Reduced Cartilage Quality: Matched-Pair Analysis Using T2-Weighted Mapping

Background: Graft hypertrophy is common after matrix-based autologous chondrocyte implantation (ACI) in the knee joint. However, it is not clear whether graft hypertrophy is a complication or an adjustment reaction in the cartilage regeneration after ACI. Purpose: To analyze the cartilage quality of the ACI regeneration with graft hypertrophy using T2-weighted mapping. Study Design: Cohort study;Level of evidence, 2. Methods: A total of 91 patients with isolated cartilage defects (International Cartilage Repair Society [ICRS] grade III-IV) of the knee were treated with Novocart 3D, a third-generation, matrix-based, ACI procedure in the knee joint. All patients were evaluated with a standardized magnetic resonance imaging protocol after 3, 6, 12, 24, 36, and 48 months postoperatively. For morphological and biochemical assessment, the T2-weighted relaxation times of the ACI grafts as well as the healthy surrounding cartilage were determined. The results of the 20 patients with graft hypertrophy (hypertrophic group) were compared with the results of 21 matched patients without graft hypertrophy (nonhypertrophic group) after ACI. Match-paired analysis was performed by comparison of age, defect size, and body mass index. Results: The T2-weighted relaxation times of the ACI graft showed significant improvement, with values decreasing from 52.1 milliseconds to 33.3 milliseconds after 48 months. After 12 months, the T2-weighted relaxation times were constant and comparable with the healthy surrounding cartilage. Graft hypertrophy was seen in 22% (n = 20) of the patients who underwent ACI. A significant difference in T2-weighted relaxation times between the hypertrophic and nonhypertrophic ACI grafts could not be found except after 36 months (hypertrophic T2-weighted relaxation time/nonhypertrophic T2-weighted relaxation time: 3 months, 48.0/56.4 ms, P = .666;6 months, 45.6/42.5 ms, P = .280;12 months, 39.3/34.7 ms, P = .850;24 months, 34.8/32.2 ms, P =.742;36 months, 34.6/38.2 ms, P = .030;48 months, 34.2/32.3 ms, P = .693). Conclusion: The T2-weighted relaxation time of the ACI graft cartilage showed significant improvements over the observation period of 4 years postoperatively. After 2 years, graft maturation was completed. Graft hypertrophy after ACI was seen in 22% of the patients. Reduced cartilage quality could not be found in patients with graft hypertrophy after ACI

The influence of different footprint preparation techniques on tissue regeneration in rotator cuff repair in an animal model

Introduction: Rotator cuff tears are common diseases of the upper extremity. There are no recommendations to the surgeon on how to prepare the footprint to ensure optimal tendon-to-bone healing. However, biologic augmentation using stem cells and growth factors is considered to encourage the healing process of the tendon. The aim of the study was to investigate the biomechanical and histological outcome of different footprint preparations in rotator cuff repair. Material and methods: One hundred and eighty-nine Sprague-Dawley rats were randomly assigned to either spongialization, radiofrequency ablation or an untreated control group. Rats were killed after 1 or 7 weeks for histological evaluation or after 7 weeks for biomechanical testing. Results: Histological evaluation showed better tissue organization in the control and spongialization group compared to the radiofrequency ablation group. The highest collagen I to collagen III quotient was found in the control group, followed closely by the spongialization group. Measured quotients showed a decrease in the values after 1 week compared to the values after 7 weeks, except in the radiofrequency ablation group, where an increase was detected. A significant difference was found in the load to failure test comparing the radiofrequency ablation group to the spongialization group (p = 0.0409) and control group (p = 0.014), but not comparing the spongialization group to the control group (p = 0.2456). Conclusions: The results of this study suggest that spongialization of the footprint before attaching the torn supraspinatus tendon can lead to better structural properties and higher quality of tendon-to-bone restoration at the insertion area when compared with radiofrequency ablation

Appearance normalization of histology slides

This paper presents a method for automatic color and intensity normalization of digitized histology slides stained with two different agents. In comparison to previous approaches, prior information on the stain vectors is used in the plane estimation process, resulting in improved stability of the estimates. Due to the prevalence of hematoxylin and eosin staining for histology slides, the proposed method has significant practical utility. In particular, it can be used as a first step to standardize appearance across slides and is effective at countering effects due to differing stain amounts and protocols and counteracting slide fading. The approach is validated against non-prior plane-fitting using synthetic experiments and 13 real datasets. Results of application of the method to adjustment of faded slides are given, and the effectiveness of the method in aiding statistical classification is shown