Understanding the Capacitance of PEDOT:PSS

Poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is the most studied and explored mixed ion‐electron conducting polymer system. PEDOT:PSS is commonly included as an electroactive conductor in various organic devices, e.g., supercapacitors, displays, transistors, and energy‐converters. In spite of its long‐term use as a material for storage and transport of charges, the fundamentals of its bulk capacitance remain poorly understood. Generally, charge storage in supercapacitors is due to formation of electrical double layers or redox reactions, and it is widely accepted that PEDOT:PSS belongs to the latter category. Herein, experimental evidence and theoretical modeling results are reported that significantly depart from this commonly accepted picture. By applying a two‐phase, 2D modeling approach it is demonstrated that the major contribution to the capacitance of the two‐phase PEDOT:PSS originates from electrical double layers formed along the interfaces between nanoscaled PEDOT‐rich and PSS‐rich interconnected grains that comprises two phases of the bulk of PEDOT:PSS. This new insight paves a way for designing materials and devices, based on mixed ion‐electron conductors, with improved performance.     

Identification of myocardial diffuse fibrosis by 11 heartbeat MOLLI <Emphasis Type="Italic">T</Emphasis><Subscript>1</Subscript> mapping: averaging to improve precision and correlation with collagen volume fraction

Objectives

Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T ₁ mapping versus assessment at a single ventricular level.

Materials and methods

For assessment of T ₁ mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T ₁ and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T ₁, allowing calculation of partition coefficient and ECV. To assess correlation of T ₁ mapping with collagen volume fraction, a separate cohort of ten aortic stenosis patients scheduled to undergo surgery underwent one CMR scan with this 11 heartbeat MOLLI scheme, followed by intraoperative tru-cut myocardial biopsy. Six models of myocardial diffuse fibrosis assessment were established with incremental inclusion of imaging by averaging of the basal and mid-myocardial left ventricular levels, and each model was assessed for precision and correlation with collagen volume fraction.

Results

A model using 11 heart beat MOLLI imaging of two basal and two mid ventricular level averaged T ₁ maps provided improved precision (Intraclass correlation 0.93 vs 0.84) and correlation with histology (R ² = 0.83 vs 0.36) for diffuse fibrosis compared to a single mid-ventricular level alone. ECV was more precise and correlated better than native T ₁ mapping.

Conclusion

T ₁ mapping sequences with repeated averaging could be considered for applications of 11 heartbeat MOLLI, especially when small changes in native T ₁/ECV might affect clinical management.

     

Bayesian latent variable modelling of multivariate spatio-temporal variation in cancer mortality

In this article, three alternative Bayesian hierarchical latent factor models are described for spatially and temporally correlated multivariate health data. The fundamentals of factor analysis with ideas of space- time disease mapping to provide a flexible framework for the joint analysis of multiple-related diseases in space and time with a view to estimating common and disease-specific trends in cancer risk are combined. The models are applied to area-level mortality data on six diet-related cancers for Greece over the 20-year period from 1980 to 1999. The aim of this study is to uncover the spatial and temporal patterns of any latent factor(s) underlying the cancer data that could be interpreted as reflecting some aspects of the habitual diet of the Greek population.     

Exploring the performance limits of simultaneous multithreading for memory intensive applications

Simultaneous multithreading (SMT) has been proposed to improve system throughput by overlapping instructions from multiple threads on a single wide-issue processor. Recent studies have demonstrated that diversity of simultaneously executed applications can bring up significant performance gains due to SMT. However, the speedup of a single application that is parallelized into multiple threads, is often sensitive to its inherent instruction level parallelism (ILP), as well as the efficiency of synchronization and communication mechanisms between its separate, but possibly dependent threads. Moreover, as these separate threads tend to put pressure on the same architectural resources, no significant speedup can be observed. In this paper, we evaluate and contrast thread-level parallelism (TLP) and speculative precomputation (SPR) techniques for a series of memory intensive codes executed on a specific SMT processor implementation. We explore the performance limits by evaluating the tradeoffs between ILP and TLP for various kinds of instruction streams. By obtaining knowledge on how such streams interact when executed simultaneously on the processor, and quantifying their presence within each application’s threads, we try to interpret the observed performance for each application when parallelized according to the aforementioned techniques. In order to amplify this evaluation process, we also present results gathered from the performance monitoring hardware of the processor.

Addressing privacy requirements in system design: the PriS method

A major challenge in the field of software engineering is to make users trust the software that they use in their every day activities for professional or recreational reasons. Trusting software depends on various elements, one of which is the protection of user privacy. Protecting privacy is about complying with user’s desires when it comes to handling personal information. Users’ privacy can also be defined as the right to determine when, how and to what extend information about them is communicated to others. Current research stresses the need for addressing privacy issues during the system design rather than during the system implementation phase. To this end, this paper describes PriS, a security requirements engineering method, which incorporates privacy requirements early in the system development process. PriS considers privacy requirements as organisational goals that need to be satisfied and adopts the use of privacy-process patterns as a way to: (1) describe the effect of privacy requirements on business processes; and (2) facilitate the identification of the system architecture that best supports the privacy-related business processes. In this way, PriS provides a holistic approach from ‘high-level’ goals to ‘privacy-compliant’ IT systems. The PriS way-of-working is formally defined thus, enabling the development of automated tools for assisting its application.

Contention Resolution under Selfishness

In many communications settings, such as wired and wireless local-area networks, when multiple users attempt to access a communication channel at the same time, a conflict results and none of the communications are successful. Contention resolution is the study of distributed transmission and retransmission protocols designed to maximize notions of utility such as channel utilization in the face of blocking communications. An additional issue to be considered in the design of such protocols is that selfish users may have incentive to deviate from the prescribed behavior, if another transmission strategy increases their utility. The work of Fiat et al. (in SODA ’07, pp. 179–188, SIAM, Philadelphia 2007) addresses this issue by constructing an asymptotically optimal incentive-compatible protocol. However, their protocol assumes the cost of any single transmission is zero, and the protocol completely collapses under non-zero transmission costs. In this paper we treat the case of non-zero transmission cost c. We present asymptotically optimal contention resolution protocols that are robust to selfish users, in two different channel feedback models. Our main result is in the Collision Multiplicity Feedback model, where after each time slot, the number of attempted transmissions is returned as feedback to the users. In this setting, we give a protocol that has expected cost Θ(n+clogn) and is in o(1)-equilibrium, where n is the number of users.     

A Discrete MRF Framework for Integrated Multi-Atlas Registration and Segmentation

Multi-atlas segmentation has emerged in recent years as a simple yet powerful approach in medical image segmentation. It commonly comprises two steps: (1) a series of pairwise registrations that establish correspondences between a query image and a number of atlases, and (2) the fusion of the available segmentation hypotheses towards labeling objects of interest. In this paper, we introduce a novel approach that solves simultaneously for the underlying segmentation labels and the multi-atlas registration. The proposed approach is formulated as a pairwise Markov Random Field, where registration and segmentation nodes are coupled towards simultaneously recovering all atlas deformations and labeling the query image. The coupling is achieved by promoting the consistency between selected deformed atlas segmentations and the estimated query segmentation. Additional membership fields are estimated, determining the participation of each atlas in labeling each voxel. Inference is performed by using a sequential relaxation scheme. The proposed approach is validated on the IBSR dataset and is compared against standard post-registration label fusion strategies. Promising results demonstrate the potential of our method.     

Job characteristics, flow, and performance: The moderating role of conscientiousness.

The present article aims to show the importance of positive work-related experiences within occupational health psychology by examining the relationship between flow at work (i.e., absorption, work enjoyment, and intrinsic work motivation) and job performance. On the basis of the literature, it was hypothesized that (a) motivating job characteristics are positively related to flow at work and (b) conscientiousness moderates the relationship between flow and other ratings of (in-role and out-of-role) performance. The hypotheses were tested on a sample of 113 employees from several occupations. Results of moderated structural equation modeling analyses generally supported the hypotheses. Motivating job characteristics were predictive of flow, and flow predicted in-role and extra-role performance, for only conscientious employees. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetric Inorganic Membranes Through Langmuir–Blodgett Deposition and Plasma Processing

Nanoporous 7930 Vycor silica tubes with Langmuir–Blodgett (LB) deposited arachidic acid salts undergo oxidative plasma treatment to yield fully inorganic asymmetric membranes. Membranes from precursors with different numbers of LB layers are examined by differential, integral and relative permeability methods for the determination of the structural characteristics of the separating top layer. The membrane top layer is found to be dominated by medium size micropores, while a small population of defective surface sites (partially covered original pores) is also present. The gas separation potential of inorganic asymmetric membranes from ceramic oxide-LB film composites is discussed.     

Role of the Myokine Irisin on Bone Homeostasis: Review of the Current Evidence

Bone is a highly dynamic tissue that is constantly adapting to micro-changes to facilitate movement. When the balance between bone building and resorption shifts more towards bone resorption, the result is reduced bone density and mineralization, as seen in osteoporosis or osteopenia. Current treatment strategies aimed to improve bone homeostasis and turnover are lacking in efficacy, resulting in the search for new preventative and nutraceutical treatment options. The myokine irisin, since its discovery in 2012, has been shown to play an important role in many tissues including muscle, adipose, and bone. Evidence indicate that irisin is associated with increased bone formation and decreased bone resorption, leading to reduced risk of osteoporosis in post-menopausal women. In addition, low serum irisin levels have been found in individuals with osteoporosis and osteopenia. Irisin targets key signaling proteins, promoting osteoblastogenesis and reducing osteoclastogenesis. The present review summarizes the existing evidence regarding the effects of irisin on bone homeostasis.