People in different age groups show different hip-joint morphology

It has been suggested that the distribution of the subchondral bone density may be regarded as the expression of the long-term effective stress in a joint, and previous results indicate the regularity of the distribution of subchondral bone density as a function of the passing demands made upon a joint. Computed tomography-osteoabsorptiometry has been developed to visualize the area distribution of subchondral mineralization in the major joints in vivo. The purpose of this study was to display the distribution of subchondral bone density in the acetabular cup of patients of different ages. Computer tomography data files of hip joints of 27 patients (18–89 years) were used. Density ranges, image analysis, and area presentation of the distribution of subchondral mineralization are presented. The maximal subchondral mineralization in young persons is found both in the ventral and dorsal part of the acetabular roof. In older people, however, the densest areas are most often found at the zenith of the acetabulum. These morphological results could be well explained by the experimental results of other authors who found a joint incongruity in young persons with contact areas in the ventral and dorsal part of the acetabulum. With advancing age a decrease in incongruence is found, leading to an increased stress in the dome, i.e. in the area where degenerative changes are often found

Regulation of Placental Calcium Transport and Offspring Bone Health

Osteoporosis causes considerable morbidity and mortality in later life, and the risk of the disease is strongly determined by peak bone mass, which is achieved in early adulthood. Poor intrauterine and early childhood growth are associated with reduced peak bone mass, and increased risk of osteoporotic fracture in older age. In this review we describe the regulatory aspects of intrauterine bone development, and then summarize the evidence relating early growth to later fracture risk. Physiological systems include vitamin D, parathyroid hormone, leptin, GH/IGF-1; finally the potential role of epigenetic processes in the underlying mechanisms will be explored. Thus factors such as maternal lifestyle, diet, body build, physical activity, and vitamin D status in pregnancy all appear to influence offspring bone mineral accrual. These data demonstrate a likely interaction between environmental factors and gene expression, a phenomenon ubiquitous in the natural world (developmental plasticity), as the potential key process. Intervention studies are now required to test the hypotheses generated by these epidemiological and physiological findings, to inform potential novel public health interventions aimed at improving childhood bone health and reducing the burden of osteoporotic fracture in future generations

Chemostratigraphy and depositional environment of an Ordovician sedimentary section across the Miramichi Group - Tetagouche Group contact, northeastern New Brunswick

A thick section of Ordovician sedimentary rocks underlies and overlies felsic to mafic volcanic rocks of the Tetagouche Group, Bathurst Mining Camp. The dark grey quartzose slates and siltstones of the Patrick Brook Formation (Miramichi Group) occur below the volcanic rocks, whereas the dark grey to black slates and siltstones of the Boucher Brook Formation (Tetagouche Group) are intercalated with the volcanic rocks and overlie the sequence. The Miramichi-Tctagouche contact represents the interpreted Gander-Dunnage boundary in northeastern New Brunswick. Distinguishing between these two simitar formations is important for stratigraphic and geo-tectonic interpretations of the Bathurst Mining Camp and for exploration in these sequences. The geochemical composition of a semi-con form able section of rocks from the Boucher Brook (Middle to Late? Ordovician) and Patrick Brook (Early to Middle Ordovician) formations was determined to identify geochemical chemostratigraphic discriminants, as well as to determine the depositional environment in which these were deposited. The high AI2O3 and distinctly higher high-field-strength elements (LREE, Th, HREE, and Y) in the Patrick Brook rocks are characteristic of mature sedimentary rocks and indicate intense chemical weathering (tropical environment) in the source regions, which is consistent with their compositional similarity to Avalon-derived shales analogous to Gander Zone sedimentary rocks. The Boucher Brook slates and siltstones are immature sedimentary rocks based on the preservation of albite and the less coherent trace-element systematics to phyllosilicate indices (AI2O3 and K2O). The Boucher Brook Formation is probably derived from the associated volcanic rocks. The higher Mn and Fe and positive Ce/Ce* anomaly in some Boucher Brook Formation compared to the Patrick Brook rocks indicate that the Boucher Brook rocks in this section were deposited in a transitional anoxic/ oxic environment. The Patrick Brook rocks that immediately precede felsic volcanism and formation of massive sulphide deposits are highly reduced based on C and S contents, which is consistent with the sulphur isotope data. Moderately heavy δ34S values are indicative of SO42- reduction to H2S under anoxic conditions, which is significant in the formation and preservation of massive sulphides in the basal Tetagouche sequence. RÉSUMÉ Une section épaisse de roches sédimentaires de l’Ordovicien est sus-jacente ct sous-jacente à des roches volcanomafiques à volcanofelsiques du groupe de Tetagouche, dans le Camp minier de Bathurst. Des siltstones et des schistes quartzeux gris foncé de la Formation de Patrick Brook (groupe de Miramichi) sont présents au-dessous des roches volcaniques, tandis que des schistes et des siltstones gris foncé à noirs de la formation de Boucher Brook (groupe de Tetagouche) sont intercales dans les roches volcaniques et recouvrent la séquence. La surface de contact de Miramichi-Tetagouche représente ce qu'on interprèts comme la limite de Gander-Dunnage dans le nord-est du Nouveau-Brunswick. Il est important d'établir une distinction entre ces deux formations semblables pour les interprétations stratigraphiques du Camp minier de Bathurst et pour l'exploration dans ces séquences. On a détermine la composition géochimique d'une section semi-concordante de roches de Boucher Brook (Ordovicien moyen à tardif?) et de Patrick Brook (Ordovicien inférieur à moyen) afin de repérer les discriminants chimiostratigraphiques géochimiques ainsi que pour définir le milieu sédimentaire dans lequel ceux-ci ont été deposes. La quantité prononcée d'Al2O3 et la présence distinctement supérieure d'éléments d'intensité de champ élevée (éléments de terres rares légers, Th, éléments de terres rares lourds et Y) dans les roches de Patrick Brook constituent des traits caractérstiques de roches sédimentaires matures; el les témoignent d'une altération climatique chimique intense (milieu tropical) dans les regions d'origine, ce qui est compatible avec la similarité de leur composition avec les schistes en provenance d'Avalon analogues aux roches sédimentaires de la zone de Gander. Les schistes et les siltstones de Boucher Brook sont des roches sédimentaires immatures basées sur la conservation d'albite et la corrélation d'éléments traces moins cohérents avec les indices de phyllosilicates (AI2O3). La Formation de Boucher Brook provient probabtement de roches volcaniques connexes. La proportion supérieure de Mn et de Fe et l’anomalie positive de Ce/Ce* dans certaines parties de la Formation de Boucher Brook révèlcnt que les roches de Boucher Brook de cette section ont été déposées dans un milieu anoxique / oxique de transition. Les roches de Patrick Brook qui ont immédiatement précedé le volcanisme felsique et la formation de gitcs de sulfures massifs ont, à en juger par Icur teneur en C et en S, subi une réduction importante, ce qui correspond aux données isotopiques relatives au soufre. Les valeurs moyennement prononcées de δ34S temoignent d'une réduction du SO42- en H2S dans des conditions anoxiques, un phénomène déterminant dans la formation et la conservation des sulfures massifs dans la séquence basale de Tetagouche. [Traduit par la rédaction

Iterative Segmentation from Limited Training Data: Applications to Congenital Heart Disease

We propose a new iterative segmentation model which can be accurately learned from a small dataset. A common approach is to train a model to directly segment an image, requiring a large collection of manually annotated images to capture the anatomical variability in a cohort. In contrast, we develop a segmentation model that recursively evolves a segmentation in several steps, and implement it as a recurrent neural network. We learn model parameters by optimizing the interme- diate steps of the evolution in addition to the final segmentation. To this end, we train our segmentation propagation model by presenting incom- plete and/or inaccurate input segmentations paired with a recommended next step. Our work aims to alleviate challenges in segmenting heart structures from cardiac MRI for patients with congenital heart disease (CHD), which encompasses a range of morphological deformations and topological changes. We demonstrate the advantages of this approach on a dataset of 20 images from CHD patients, learning a model that accurately segments individual heart chambers and great vessels. Com- pared to direct segmentation, the iterative method yields more accurate segmentation for patients with the most severe CHD malformations.Comment: Presented at the Deep Learning in Medical Image Analysis Workshop, MICCAI 201

Adversarial Personalized Ranking for Recommendation

Item recommendation is a personalized ranking task. To this end, many recommender systems optimize models with pairwise ranking objectives, such as the Bayesian Personalized Ranking (BPR). Using matrix Factorization (MF) --- the most widely used model in recommendation --- as a demonstration, we show that optimizing it with BPR leads to a recommender model that is not robust. In particular, we find that the resultant model is highly vulnerable to adversarial perturbations on its model parameters, which implies the possibly large error in generalization. To enhance the robustness of a recommender model and thus improve its generalization performance, we propose a new optimization framework, namely Adversarial Personalized Ranking (APR). In short, our APR enhances the pairwise ranking method BPR by performing adversarial training. It can be interpreted as playing a minimax game, where the minimization of the BPR objective function meanwhile defends an adversary, which adds adversarial perturbations on model parameters to maximize the BPR objective function. To illustrate how it works, we implement APR on MF by adding adversarial perturbations on the embedding vectors of users and items. Extensive experiments on three public real-world datasets demonstrate the effectiveness of APR --- by optimizing MF with APR, it outperforms BPR with a relative improvement of 11.2% on average and achieves state-of-the-art performance for item recommendation. Our implementation is available at: https://github.com/hexiangnan/adversarial_personalized_ranking.Comment: SIGIR 201

Variational Deep Semantic Hashing for Text Documents

As the amount of textual data has been rapidly increasing over the past decade, efficient similarity search methods have become a crucial component of large-scale information retrieval systems. A popular strategy is to represent original data samples by compact binary codes through hashing. A spectrum of machine learning methods have been utilized, but they often lack expressiveness and flexibility in modeling to learn effective representations. The recent advances of deep learning in a wide range of applications has demonstrated its capability to learn robust and powerful feature representations for complex data. Especially, deep generative models naturally combine the expressiveness of probabilistic generative models with the high capacity of deep neural networks, which is very suitable for text modeling. However, little work has leveraged the recent progress in deep learning for text hashing. In this paper, we propose a series of novel deep document generative models for text hashing. The first proposed model is unsupervised while the second one is supervised by utilizing document labels/tags for hashing. The third model further considers document-specific factors that affect the generation of words. The probabilistic generative formulation of the proposed models provides a principled framework for model extension, uncertainty estimation, simulation, and interpretability. Based on variational inference and reparameterization, the proposed models can be interpreted as encoder-decoder deep neural networks and thus they are capable of learning complex nonlinear distributed representations of the original documents. We conduct a comprehensive set of experiments on four public testbeds. The experimental results have demonstrated the effectiveness of the proposed supervised learning models for text hashing.Comment: 11 pages, 4 figure

A critical role for network structure in seizure onset: a computational modeling approach

Published onlineJournal ArticleRecent clinical work has implicated network structure as critically important in the initiation of seizures in people with idiopathic generalized epilepsies. In line with this idea, functional networks derived from the electroencephalogram (EEG) at rest have been shown to be significantly different in people with generalized epilepsy compared to controls. In particular, the mean node degree of networks from the epilepsy cohort was found to be statistically significantly higher than those of controls. However, the mechanisms by which these network differences can support recurrent transitions into seizures remain unclear. In this study, we use a computational model of the transition into seizure dynamics to explore the dynamic consequences of these differences in functional networks. We demonstrate that networks with higher mean node degree are more prone to generating seizure dynamics in the model and therefore suggest a mechanism by which increased mean node degree of brain networks can cause heightened ictogenicity.Medical Research Counci

The UK National Homicide Therapeutic Service: a retrospective naturalistic study among 929 bereaved individuals

Homicidal bereavement puts survivors at risk of developing a broad range of lasting and severe mental health problems. Previous research has often relied on relatively small and homogenous samples. Still, little is known about what factors influence the expression of symptoms following homicidal bereavement. Preventive and curative treatments often do not consider the complex coherence between the emotional, judicial, financial, and societal challenges that likely arise following a homicide. Despite the severity of its consequences on mental health, no gold standard for the preventative and curative treatment of mental health issues in homicide survivors exists. We aimed to introduce a time-limited, traumatic grief-focused outreaching model of care designed specifically for homicide survivors, and to examine its potential effectiveness. Furthermore, we aimed to investigate what factors influence the severity of mental health problems and response to treatment. In the current study, self-reported data on five different outcome measures, namely, symptoms of posttraumatic stress, prolonged grief, depression, anxiety, and functional impairment were available from 929 homicidally bereaved treatment receiving adults. We used Latent Growth Modeling to analyze our repeated measures data and to classify individuals into distinct groups based on individual response patterns. Results showed that the current model of care is likely to be effective in reducing mental health complaints following homicidal bereavement. Having a history of mental illness, being younger of age and female, and having lost either a child or spouse consistently predicted greater symptom severity and functional impairment at baseline. For change in symptom severity and functional impairment during treatment, having a history of mental illness was the only consistent predictor across all outcomes. This study was limited by its reliance on self-reported data and cross-sectional design without a control group. Future prospective, longitudinal research across different cultures is needed in order to replicate the current findings and enhance generalizability. That notwithstanding, findings provide a first step toward evaluating a novel service-delivery approach for homicide survivors and provide further insight in the development of mental health complaints following bereavement by homicide