Constitutive Model for Time-Dependent Flows of Shear-Thickening Suspensions

We develop a tensorial constitutive model for dense, shear-thickening particle suspensions subjected to time-dependent flow. Our model combines a recently proposed evolution equation for the suspension microstructure in rate-independent materials with ideas developed previously to explain the steady flow of shear-thickening ones, whereby friction proliferates among compressive contacts at large particle stresses. We apply our model to shear reversal, and find good qualitative agreement with particle-level, discrete-element simulations whose results we also present

Antibodies to Seasonal Coronaviruses Rarely Cross-React with SARS-CoV-2: Findings from an African Birth Cohort

Antibodies to seasonal human-coronaviruses (sHCoV) may cross-protect against SARS-CoV-2. We investigated antibody responses in biobanked serum obtained before the pandemic from infants with polymerase chain reaction-confirmed sHCoV. Among 141 samples with antibodies to sHCoV, 4 (2.8%) were positive for SARS-CoV-2-S1 and 8 (5.7%) for SARS-CoV-2-S2. Antibodies to sHCoV rarely cross-react with SARS-CoV-2 antigens and are unlikely to account for mild pediatric illness

Universality, limits and predictability of gold-medal performances at the Olympic Games

Inspired by the Games held in ancient Greece, modern Olympics represent the world's largest pageant of athletic skill and competitive spirit. Performances of athletes at the Olympic Games mirror, since 1896, human potentialities in sports, and thus provide an optimal source of information for studying the evolution of sport achievements and predicting the limits that athletes can reach. Unfortunately, the models introduced so far for the description of athlete performances at the Olympics are either sophisticated or unrealistic, and more importantly, do not provide a unified theory for sport performances. Here, we address this issue by showing that relative performance improvements of medal winners at the Olympics are normally distributed, implying that the evolution of performance values can be described in good approximation as an exponential approach to an a priori unknown limiting performance value. This law holds for all specialties in athletics-including running, jumping, and throwing-and swimming. We present a self-consistent method, based on normality hypothesis testing, able to predict limiting performance values in all specialties. We further quantify the most likely years in which athletes will breach challenging performance walls in running, jumping, throwing, and swimming events, as well as the probability that new world records will be established at the next edition of the Olympic Games.Comment: 8 pages, 3 figures, 1 table. Supporting information files and data are available at filrad.homelinux.or

Intra-articular vs. systemic administration of etanercept in antigen-induced arthritis in the temporomandibular point. Part I: histological effects

<p>Abstract</p> <p>Background</p> <p>Temporomandibular joint (TMJ) arthritis in children causes alterations in craniomandibular growth. This abnormal growth may be prevented by an early anti-inflammatory intervention. We have previously shown that intra-articular (IA) corticosteroid reduces TMJ inflammation, but causes concurrent mandibular growth inhibition in young rabbits. Blockage of TNF-α has already proven its efficacy in children with juvenile idiopathic arthritis not responding to standard therapy. In this paper we evaluate the effect of IA etanercept compared to subcutaneous etanercept in antigen-induced TMJ-arthritis in rabbits on histological changes using histomorphometry and stereology. This article presents the data and discussion on the anti-inflammatory effects of systemic and IA etanercept. In Part II the data on the effects of systemic and IA etanercept on facial growth are presented.</p> <p>Methods</p> <p>Forty-two rabbits (10 weeks old) pre-sensitized with ovalbumin and locally induced inflammation in the temporomandibular joints were divided into three groups: a placebo group receiving IA saline injections in both joints one week after arthritis induction (n = 14), an IA etanercept group receiving 0.1 mg/kg etanercept per joint one week after arthritis induction (n = 14) and a systemic etanercept group receiving 0.8 mg/kg etanercept weekly throughout the 12-week study (n = 14). Arthritis was maintained by giving four inductions three weeks apart. Additional IA saline or etanercept injections were also given one week after the re-inductions. Histomorphometric and unbiased stereological methods (optical fractionator) were used to assess and estimate the inflammation in the joints.</p> <p>Results</p> <p>The histomorphometry showed synovial proliferation in all groups. The plasma cell count obtained by the optical fractionator was significantly reduced when treating with systemic etanercept but not with IA etanercept. Semi-quantitative assessments of synovial proliferation and subsynovial inflammation also showed reduced inflammation in the systemic etanercept group. However, the thickness of the synovial lining and volume of the subsynovial connective tissue showed no differences between the groups.</p> <p>Conclusion</p> <p>An anti-inflammatory effect of systemic etanercept on the synovial tissues in the temporomandibular joint was shown. However, IA etanercept at the given dose had no significant effect on the severity of chronic inflammation on the parameters here tested in ovalbumin antigen-induced arthritis.</p

Retrograde semaphorin-plexin signalling drives homeostatic synaptic plasticity.

Homeostatic signalling systems ensure stable but flexible neural activity and animal behaviour. Presynaptic homeostatic plasticity is a conserved form of neuronal homeostatic signalling that is observed in organisms ranging from Drosophila to human. Defining the underlying molecular mechanisms of neuronal homeostatic signalling will be essential in order to establish clear connections to the causes and progression of neurological disease. During neural development, semaphorin-plexin signalling instructs axon guidance and neuronal morphogenesis. However, semaphorins and plexins are also expressed in the adult brain. Here we show that semaphorin 2b (Sema2b) is a target-derived signal that acts upon presynaptic plexin B (PlexB) receptors to mediate the retrograde, homeostatic control of presynaptic neurotransmitter release at the neuromuscular junction in Drosophila. Further, we show that Sema2b-PlexB signalling regulates presynaptic homeostatic plasticity through the cytoplasmic protein Mical and the oxoreductase-dependent control of presynaptic actin. We propose that semaphorin-plexin signalling is an essential platform for the stabilization of synaptic transmission throughout the developing and mature nervous system. These findings may be relevant to the aetiology and treatment of diverse neurological and psychiatric diseases that are characterized by altered or inappropriate neural function and behaviour

Postglacial expansion of the arctic keystone copepod calanus glacialis

Calanus glacialis, a major contributor to zooplankton biomass in the Arctic shelf seas, is a key link between primary production and higher trophic levels that may be sensitive to climate warming. The aim of this study was to explore genetic variation in contemporary populations of this species to infer possible changes during the Quaternary period, and to assess its population structure in both space and time. Calanus glacialis was sampled in the fjords of Spitsbergen (Hornsund and Kongsfjorden) in 2003, 2004, 2006, 2009 and 2012. The sequence of a mitochondrial marker, belonging to the ND5 gene, selected for the study was 1249 base pairs long and distinguished 75 unique haplotypes among 140 individuals that formed three main clades. There was no detectable pattern in the distribution of haplotypes by geographic distance or over time. Interestingly, a Bayesian skyline plot suggested that a 1000-fold increase in population size occurred approximately 10,000 years before present, suggesting a species expansion after the Last Glacial Maximum.GAME from the National Science Centre, the Polish Ministry of Science and Higher Education Iuventus Plus [IP2014 050573]; FCT-PT [CCMAR/Multi/04326/2013]; [2011/03/B/NZ8/02876

Astrobiological Complexity with Probabilistic Cellular Automata

Search for extraterrestrial life and intelligence constitutes one of the major endeavors in science, but has yet been quantitatively modeled only rarely and in a cursory and superficial fashion. We argue that probabilistic cellular automata (PCA) represent the best quantitative framework for modeling astrobiological history of the Milky Way and its Galactic Habitable Zone. The relevant astrobiological parameters are to be modeled as the elements of the input probability matrix for the PCA kernel. With the underlying simplicity of the cellular automata constructs, this approach enables a quick analysis of large and ambiguous input parameters' space. We perform a simple clustering analysis of typical astrobiological histories and discuss the relevant boundary conditions of practical importance for planning and guiding actual empirical astrobiological and SETI projects. In addition to showing how the present framework is adaptable to more complex situations and updated observational databases from current and near-future space missions, we demonstrate how numerical results could offer a cautious rationale for continuation of practical SETI searches.Comment: 37 pages, 11 figures, 2 tables; added journal reference belo

Fully covered self-expanding metal stents placed temporarily in the bile duct: safety profile and histologic classification in a porcine model

<p>Abstract</p> <p>Background</p> <p>Fully covered Self-Expanding metal stents (FCSEMS) have been shown efficacious in palliating malignant biliary obstructions. There is little data analyzing mucosal response to their temporary placement in the bile duct.</p> <p>Methods</p> <p>Ten mini pigs underwent endoscopic placement of a FCSEMS (Wallflex, Boston Scientific). FCSEMS were kept in place for three months. At the end of the 3 months, FCSEMS were removed endoscopically. Five pigs were euthanized and their bile ducts harvested. The other five were kept alive for another month post removal. A single pathologist, created a scoring system (to determine degree of inflammation, fibrosis, and epithelial injury), examined all specimens in a blinded fashion.</p> <p>Results</p> <p>Four FCSEMS spontaneously migrated in the duodenum. On post mortem examination, mild mucosal thickness was noted in three bile duct specimens while superficial inflammation of the bile duct was noted in five animals. Histologic examination of the bile duct revealed focal acute inflammation in both groups. For the 5 animals euthanized immediately after stent removal, there was a tendency to have superficial mucosal erosion and fibrosis. In contrast, increased chronic inflammation was more commonly seen in the animals 1 month post stent removal, with all animals in this group showing moderate degrees of mononuclear inflammatory cell mucosal infiltrates. No severe inflammatory or fibrotic duct injury was observed in any of the study animals, with degree of injury graded as mild to moderate.</p> <p>Conclusion</p> <p>FCSEMS appear to induce minimal tissue overgrowth or fibrosis post placement. Ease of removability and no significant histologic injury are advantages noted with FCSEMS., however, further studies are needed to evaluate treating benign biliary strictures with FCSEMS in humans.</p

Methylmercury Exposure and Adverse Cardiovascular Effects in Faroese Whaling Men

Background: Methylmercury (MeHg), a worldwide contaminant found in fish and seafood, has been linked to an increased risk of cardiovascular mortality. Objective: We examined 42 Faroese whaling men (30–70 years of age) to assess possible adverse effects within a wide range of MeHg exposures from consumption of pilot whale meat. Methods: We assessed exposure levels from mercury analysis of toenails and whole blood (obtained at the time of clinical examination), and a hair sample collected 7 years previously. Outcome measures included heart rate variability (HRV), blood pressure (BP), common carotid intima-media thickness (IMT), and brainstem auditory evoked potentials (BAEP). We carried out multiple regression and structural equation model (SEM) analyses to determine the confounder-adjusted effect of mercury exposure. Taking into account correlations among related measures, we categorized exposure and outcomes in groups to derive latent exposure and response variables in SEMs. We used multiple regression analysis to compare the predictive validity of individual exposure biomarkers and the latent exposure variable on individual and latent outcomes. Results: The toenail mercury concentrations varied widely and had a geometric mean of 2.0 μg/g; hair concentrations averaged about 3-fold higher. Mercury exposure was significantly associated with increased BP and IMT. This effect was reflected by SEMs, but mercury in toenails tended to be the best effect predictor. Conclusions: The results support the notion that increased MeHg exposure promotes the development of cardiovascular disease