Assessment of the Validity and Reproducibility of a Novel Standardized Test Meal for the Study of Postprandial Triacylglycerol Concentrations

Lipotest^® is a standardized fat‐rich meal designed for use as a test meal during a fat tolerance test (FTT) for the study of postprandial triacylglycerol (TAG) concentrations. Herein we examined the precision and reproducibility of examination using Lipotest^® on postprandial TAG levels. A total of 26 healthy consenting subjects were examined twice after 8–10 h fasting with an interval of approximately 1 week apart. Blood samples were collected at baseline and 1, 2, 3, and 4 h after consumption of the test meal for measurement of plasma total TAG levels. We examined agreement, precision, and accuracy between the two visits using the Altman plots and correlation coefficient. Reproducibility was tested using the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Moreover, the area under the curve (AUC) as a summary measure of the overall postprandial TAG levels was calculated. The agreement, precision (r ≥ 0.74, p < 0.001), and accuracy (≥0.99) between the measurements in plasma TAG during Lipotest^® testing in the two visits were high. In terms of reproducibility, the values of CV were 15.59–23.83% while those of ICC were ≥0.75. The values of the AUCs in the visits were not different (p = 0.87). A single measurement of plasma TAG levels at 4 h after Lipotest^® consumption depicted peak postprandial TAG concentration. A FTT using Lipotest^® as a standardized meal has good precision and reproducibility for the study of postprandial TAG levels in healthy individuals. A single determination of plasma TAG concentration at 4 h after Lipotest^® consumption captures peak postprandial TAG response.     

Does hemodiafiltration reduce vascular stiffness measured by aortic pulse wave velocity compared with high‐flux hemodialysis?

Hemodialfiltration (HDF) has been reported to reduce the frequency of intradialytic hypotension compared with hemodialysis (HD). We wished to determine whether HDF resulted in improvement of arterial stiffness compared with HD. We reviewed peripheral blood pressure and pulse wave velocity measurements in a cross‐sectional analysis of stable HDF and HD outpatients. One hundred forty‐one HDF patients were matched to 148 HD patients in terms of age, sex, prevalence of diabetes, peripheral blood pressure, and body mass. Pulse wave velocity was not different between the HD and HDF cohorts (median 9.1 [8.0–10.7] m/s vs. 9.7 [8.5–11.6] m/s). Similarly, there were no differences in central aortic pressure (149.2 ± 30.9 mmHg vs. 151.9 ± 35.2 mmHg), or aortic (39 [25.1–51.2]% vs. 38.6 [25.8–51.4]%) and brachial (3.8 [?24.3 to 26.9]% vs. 3 [?22.4 to 27.1]%) augmentation indices, respectively. Pulse wave velocity did not differ between adult patients treated by HD and HDF, and similarly, there were no differences in central aortic pressure, aortic or brachial augmentation indices, and cardiac diastolic perfusion. Our study suggests that HDF does not appear to offer any benefit over HD in terms of vascular stiffness.     

Rust morphology characterization of polyurethane and acrylic-based marine antifouling paints after salt spray test on scribed specimens

A newly developed, polyurethane-based, marine antifouling coating, containing 2% immobilized Econea, was examined in terms of its anticorrosion performance. The novelty of the experimental formulation arises from the immobilization of the biocide which minimizes leaching and was accomplished via a newly developed functionalization method, based on reaction of the biocide with highly reactive isocyanate functionality. The painting system was applied on steel specimens, then scribed with a sharp cutter and examined for 12 weeks in cyclic salt spray exposure. Identification of the rust morphologies was performed with XRD, Raman spectroscopy, SEM, and EDS methods. The absence of paint deformation during the experiment led to the formation of compact corrosion products, firmly adherent to the substrate, allowing transformation to more protective forms, such as oxides (hematite, maghemite, magnetite) and the least harmful of the oxyhydroxides (goethite, feroxyhyte), found in the mixture, ensuring sufficient corrosion protection. The unscratched part of the paint served as a barrier to corrosion product expansion beyond the scribed areas. An acrylic-based antifouling system was also examined for reasons of comparison. The experimental formulation exhibited superior anticorrosion performance overall, since the acrylic system presented extended material loss, blistering, checking, and extensive substrate rust coverage beneath the multilayer coat, implying unsatisfactory corrosion protection.     

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.     

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.     

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.

Drivers' communicative interactions: on-road observations and modelling for integration in future automation systems

Social interactions with other road users are an essential component of the driving activity and may prove critical in view of future automation systems; still up to now they have received only limited attention in the scientific literature. In this paper, it is argued that drivers base their anticipations about the traffic scene to a large extent on observations of social behaviour of other ‘animate human-vehicles’. It is further argued that in cases of uncertainty, drivers seek to establish a mutual situational awareness through deliberate communicative interactions. A linguistic model is proposed for modelling these communicative interactions. Empirical evidence from on-road observations and analysis of concurrent running commentary by 25 experienced drivers support the proposed model. It is suggested that the integration of a social interactions layer based on illocutionary acts in future driving support and automation systems will improve their performance towards matching human driver's expectations.

Practitioner Summary: Interactions between drivers on the road may play a significant role in traffic coordination. On-road observations and running commentaries are presented as empirical evidence to support a model of such interactions; incorporation of drivers' interactions in future driving support and automation systems may improve their performance towards matching driver's expectations.     

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.