Effects of study precision and risk of bias in networks of interventions: a network meta-epidemiological study

BACKGROUND Empirical research has illustrated an association between study size and relative treatment effects, but conclusions have been inconsistent about the association of study size with the risk of bias items. Small studies give generally imprecisely estimated treatment effects, and study variance can serve as a surrogate for study size. METHODS We conducted a network meta-epidemiological study analyzing 32 networks including 613 randomized controlled trials, and used Bayesian network meta-analysis and meta-regression models to evaluate the impact of trial characteristics and study variance on the results of network meta-analysis. We examined changes in relative effects and between-studies variation in network meta-regression models as a function of the variance of the observed effect size and indicators for the adequacy of each risk of bias item. Adjustment was performed both within and across networks, allowing for between-networks variability. RESULTS Imprecise studies with large variances tended to exaggerate the effects of the active or new intervention in the majority of networks, with a ratio of odds ratios of 1.83 (95% CI: 1.09,3.32). Inappropriate or unclear conduct of random sequence generation and allocation concealment, as well as lack of blinding of patients and outcome assessors, did not materially impact on the summary results. Imprecise studies also appeared to be more prone to inadequate conduct. CONCLUSIONS Compared to more precise studies, studies with large variance may give substantially different answers that alter the results of network meta-analyses for dichotomous outcomes.

Matching Recall and Storage in Sequence Learning with Spiking Neural Networks

Storing and recalling spiking sequences is a general problem the brain needs to solve. It is, however, unclear what type of biologically plausible learning rule is suited to learn a wide class of spatiotemporal activity patterns in a robust way. Here we consider a recurrent network of stochastic spiking neurons composed of both visible and hidden neurons. We derive a generic learning rule that is matched to the neural dynamics by minimizing an upper bound on the Kullback–Leibler divergence from the target distribution to the model distribution. The derived learning rule is consistent with spike-timing dependent plasticity in that a presynaptic spike preceding a postsynaptic spike elicits potentiation while otherwise depression emerges. Furthermore, the learning rule for synapses that target visible neurons can be matched to the recently proposed voltage-triplet rule. The learning rule for synapses that target hidden neurons is modulated by a global factor, which shares properties with astrocytes and gives rise to testable predictions.

The scholarly networks of Albrecht von Haller and the Economic Society of Bern – a multi-level network analysis

Here, by the example of the transfer of cultivated plants in the context of the correspondence networks of Albrecht von Haller and the Economic Society, a multi-level network analysis is suggested. By a multi-level procedure, the chronological dynamics, the social structure, the spatial distribution and the functional networking are analyzed one after the other. These four levels of network analysis do not compete with each other but are mutually supporting. This aims at a deeper understanding of how these networks contributed to an international transfer of knowledge in the 18th century.

CAOR: Context-aware Adaptive Opportunistic Routing in Mobile Ad-hoc Networks

Opportunistic routing (OR) employs a list of candidates to improve wireless transmission reliability. However, conventional list-based OR restricts the freedom of opportunism, since only the listed nodes are allowed to compete for packet forwarding. Additionally, the list is generated statically based on a single network metric prior to data transmission, which is not appropriate for mobile ad-hoc networks (MANETs). In this paper, we propose a novel OR protocol - Context-aware Adaptive Opportunistic Routing (CAOR) for MANETs. CAOR abandons the idea of candidate list and it allows all qualified nodes to participate in packet transmission. CAOR forwards packets by simultaneously exploiting multiple cross-layer context information, such as link quality, geographic progress, energy, and mobility.With the help of the Analytic Hierarchy Process theory, CAOR adjusts the weights of context information based on their instantaneous values to adapt the protocol behavior at run-time. Moreover, CAOR uses an active suppression mechanism to reduce packet duplication. Simulation results show that CAOR can provide efficient routing in highly mobile environments. The adaptivity feature of CAOR is also validated.

The spatial distribution of water in the inner coma of Comet 9P/Tempel 1: Comparison between models and observations

The near nucleus coma of Comet 9P/Tempel 1 has been simulated with the 3D Direct Simulation Monte Carlo (DSMC) code PDSC++ (Su, C.-C. [2013]. Parallel Direct Simulation Monte Carlo (DSMC) Methods for Modeling Rarefied Gas Dynamics. PhD Thesis, National Chiao Tung University, Taiwan) and the derived column densities have been compared to observations of the water vapour distribution found by using infrared imaging spectrometer on the Deep Impact spacecraft (Feaga, L.M., A’Hearn, M.F., Sunshine, J.M., Groussin, O., Farnham, T.L. [2007]. Icarus 191(2), 134–145. http://dx.doi.org/10.1016/j.icarus.2007.04.038). Modelled total production rates are also compared to various observations made at the time of the Deep Impact encounter. Three different models were tested. For all models, the shape model constructed from the Deep Impact observations by Thomas et al. (Thomas, P.C., Veverka, J., Belton, M.J.S., Hidy, A., A’Hearn, M.F., Farnham, T.L., et al. [2007]. Icarus, 187(1), 4–15. http://dx.doi.org/10.1016/j.icarus.2006.12.013) was used. Outgassing depending only on the cosine of the solar insolation angle on each shape model facet is shown to provide an unsatisfactory model. Models constructed on the basis of active areas suggested by Kossacki and Szutowicz (Kossacki, K., Szutowicz, S. [2008]. Icarus, 195(2), 705–724. http://dx.doi.org/10.1016/j.icarus.2007.12.014) are shown to be superior. The Kossacki and Szutowicz model, however, also shows deficits which we have sought to improve upon. For the best model we investigate the properties of the outflow.

Identification, quantification, spatiotemporal distribution and genetic variation of major latex secondary metabolites in the common dandelion (Taraxacum officinale agg.)

The secondary metabolites in the roots, leaves and flowers of the common dandelion (Taraxacum officinale agg.) have been studied in detail. However, little is known about the specific constituents of the plant’s highly specialized laticifer cells. Using a combination of liquid and gas chromatography, mass spectrometry and nuclear magnetic resonance spectrometry, we identified and quantified the major secondary metabolites in the latex of different organs across different growth stages in three genotypes, and tested the activity of the metabolites against the generalist root herbivore Diabrotica balteata. We found that common dandelion latex is dominated by three classes of secondary metabolites: phenolic inositol esters (PIEs), triterpene acetates (TritAc) and the sesquiterpene lactone taraxinic acid β-d-glucopyranosyl ester (TA-G). Purification and absolute quantification revealed concentrations in the upper mg g−1 range for all compound classes with up to 6% PIEs, 5% TritAc and 7% TA-G per gram latex fresh weight. Contrary to typical secondary metabolite patterns, concentrations of all three classes increased with plant age. The highest concentrations were measured in the main root. PIE profiles differed both quantitatively and qualitatively between plant genotypes, whereas TritAc and TA-G differed only quantitatively. Metabolite concentrations were positively correlated within and between the different compound classes, indicating tight biosynthetic co-regulation. Latex metabolite extracts strongly repelled D. balteata larvae, suggesting that the latex constituents are biologically active.

Network Store: Exploring Slicing in Future 5G Networks

In this paper, we present a revolutionary vision of 5G networks, in which SDN programs wireless network functions, and where Mobile Network Operators (MNO), Enterprises, and Over-The-Top (OTT) third parties are provided with NFV-ready Network Store. The proposed Network Store serves as a digital distribution platform of programmable Virtualized Network Functions (VNFs) that enable 5G application use-cases. Currently existing application stores, such as Apple's App Store for iOS applications, Google's Play Store for Android, or Ubuntu's Software Center, deliver applications to user specific software platforms. Our vision is to provide a digital marketplace, gathering 5G enabling Network Applications and Network Functions, written to run on top of commodity cloud infrastructures, connected to remote radio heads (RRH). The 5G Network Store will be the same to the cloud as the application store is currently to a software platform.

Active eosinophilic esophagitis is characterized by epithelial barrier defects and eosinophil extracellular trap formation.

BACKGROUND Eosinophilic esophagitis (EoE) exhibits esophageal dysfunction owing to an eosinophil-predominant inflammation. Activated eosinophils generate eosinophil extracellular traps (EETs) able to kill bacteria. There is evidence of an impaired barrier function in EoE that might allow pathogens to invade the esophagus. This study aimed to investigate the presence and distribution of EETs in esophageal tissues from EoE patients and their association with possible epithelial barrier defects. METHODS Anonymized tissue samples from 18 patients with active EoE were analyzed. The presence of DNA nets associated with eosinophil granule proteins forming EETs and the expression of filaggrin, the protease inhibitor lympho-epithelial Kazal-type-related inhibitor (LEKTI), antimicrobial peptides, and cytokines were evaluated by confocal microscopy following immune fluorescence staining techniques. RESULTS Eosinophil extracellular trap formation occurred frequently and was detected in all EoE samples correlating with the numbers of infiltrating eosinophils. While the expression of both filaggrin and LEKTI was reduced, epithelial antimicrobial peptides (human beta-defensin-2, human beta-defensin-3, cathelicidin LL-37, psoriasin) and cytokines (TSLP, IL-25, IL-32, IL-33) were elevated in EoE as compared to normal esophageal tissues. There was a significant correlation between EET formation and TSLP expression (P = 0.02) as well as psoriasin expression (P = 0.016). On the other hand, a significant negative correlation was found between EET formation and LEKTI expression (P = 0.016). CONCLUSION Active EoE exhibits the presence of EETs. Indications of epithelial barrier defects in association with epithelial cytokines are also present which may have contributed to the activation of eosinophils. The formation of EETs could serve as a firewall against the invasion of pathogens.

Adaptive Beaconless Opportunistic Routing for Multimedia Distribution

User experience on watching live videos must be satisfactory even under the inuence of different network conditions and topology changes, such as happening in Flying Ad-Hoc Networks (FANETs). Routing services for video dissemination over FANETs must be able to adapt routing decisions at runtime to meet Quality of Experience (QoE) requirements. In this paper, we introduce an adaptive beaconless opportunistic routing protocol for video dissemination over FANETs with QoE support, by taking into account multiple types of context information, such as link quality, residual energy, buffer state, as well as geographic information and node mobility in a 3D space. The proposed protocol takes into account Bayesian networks to define weight vectors and Analytic Hierarchy Process (AHP) to adjust the degree of importance for the context information based on instantaneous values. It also includes a position prediction to monitor the distance between two nodes in order to detect possible route failure.

NetCodCCN: a Network Coding approach for Content-Centric Networks

Content-Centric Networking (CCN) naturally supports multi-path communication, as it allows the simultaneous use of multiple interfaces (e.g. LTE and WiFi). When multiple sources and multiple clients are considered, the optimal set of distribution trees should be determined in order to optimally use all the available interfaces. This is not a trivial task, as it is a computationally intense procedure that should be done centrally. The need for central coordination can be removed by employing network coding, which also offers improved resiliency to errors and large throughput gains. In this paper, we propose NetCodCCN, a protocol for integrating network coding in CCN. In comparison to previous works proposing to enable network coding in CCN, NetCodCCN permit Interest aggregation and Interest pipelining, which reduce the data retrieval times. The experimental evaluation shows that the proposed protocol leads to significant improvements in terms of content retrieval delay compared to the original CCN. Our results demonstrate that the use of network coding adds robustness to losses and permits to exploit more efficiently the available network resources. The performance gains are verified for content retrieval in various network scenarios.

Narrow dust jets in a diffuse gas coma: a natural product of small active regions on comets

Comets often display narrow dust jets but more diffuse gas comae when their eccentric orbits bring them into the inner solar system and sunlight sublimates the ice on the nucleus. Comets are also understood to have one or more active areas covering only a fraction of the total surface active with sublimating volatile ices. Calculations of the gas and dust distribution from a small active area on a comet’s nucleus show that as the gas moves out radially into the vacuum of space it expands tangentially, filling much of the hemisphere centered on the active region. The dust dragged by the gas remains more concentrated over the active area. This explains some puzzling appearances of comets having collimated dust jets but more diffuse gaseous atmospheres. Our test case is 67P/Churyumov–Gerasimenko, the Rosetta mission target comet, whose activity is dominated by a single area covering only 4% of its surface.

Effect of the Tiger Stripes on the water vapor distribution in Enceladus' exosphere

The jet activity emanating from Enceladus' exosphere south pole region observed by Cassini is a subject of intensive study. The in situ and remote sensing observations performed since 2005 triggered an active modeling campaign. Such modeling is essential for better understanding of the measurements performed by individual instruments as well as to link them for a more complete picture of the volatile and ice grain distribution in Enceladus' exosphere. This paper is focused on the investigation of the effect that diffuse gas sources along the Tiger Stripes have on distribution of the water vapor in Enceladus' exosphere using the updated version of our multiplume model. We have found that accounting for the gas production by Tiger Stripes is critical for interpretation of the Cassini data. According to our calculations, sources along the Tiger Stripes (apart from those originally identified by Spitale and Porco (2007)) must contribute about 23–32% to the total plume source rate, which varies in the range of (6.4–29) ×1027 s−1. The effect of the previously unidentified source suggested in the paper is found to be critical for explaining the Ultraviolet Imaging Spectrograph 2007 and 2010 observations in the whole range of the elapsed times.

Cooperative VET in Training Networks: Analysing the Free-Rider Problem in a Sociology-of-Conventions Perspective

In training networks, particularly small and medium-sized enterprises pool their resources to train apprentices within the framework of the dual VET system, while an intermediary organisation is tasked with managing operations. Over the course of their apprenticeship, the apprentices switch from one training company to another on a (half-) yearly basis. Drawing on a case study of four training networks in Switzerland and the theoretical framework of the sociology of conventions, this paper aims to understand the reasons for the slow dissemination and reluctant adoption of this promising form of organising VET in Switzerland. The results of the study show that the system of moving from one company to another creates a variety of free-rider constellations in the distribution of the collectively generated corporative benefits. This explains why companies are reluctant to participate in this model. For the network to be sustainable, the intermediary organisation has to address discontent arising from free-rider problems while taking into account that the solutions found are always tentative and will often result in new free-rider problems.

Castanea sativa in Europe: distribution, habitat, usage and threats

The sweet chestnut (Castanea sativa Mill.) is the only native species of the genus in Europe. The broad diffusion and active management by man resulted in the establishment of the species at the limits of its potential ecological range, which makes it difficult to trace its original natural area. The present distribution ranges from North-Western Africa (e.g. Morocco) to North-Western Europe (southern England, Belgium) and from south-western Asia (e.g. Turkey) to Eastern Europe (e.g. Romania), the Caucasus (Georgia, Armenia) and the Caspian Sea. In Europe the main chestnut forests are concentrated in a few countries such as Italy, France and the Iberian Peninsula. The sweet chestnut has a remarkable multipurpose character, and may be managed for timber production (coppice and high forest) as well as for fruit production (traditional orchards), including a broad range of secondary products and ecosystem services.

Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse

Pits have been observed on many cometary nuclei mapped by spacecraft(1-4). It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments(5,6) andmodels(7,8) cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts(8,9). Alternative mechanisms like explosive activity(10) have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.