A dilogarithmic integral arising in quantum field theory

Recently, an interesting dilogarithmic integral arising in quantum field theory has been closed-form evaluated in terms of the Clausen function $\text{Cl}_2(\theta)$ by Coffey [J. Math. Phys.} 49 (2008), 093508]. It represents the volume of an ideal tetrahedron in hyperbolic space and is involved in two intriguing equivalent conjectures of Borwein and Broadhurst. It is shown here, by simple and direct arguments, that this integral can be expressed by the triplet of the Clausen function values which are involved in one of the two above-mentioned conjectures.Comment: 6 page

NANO-VESICLES OF SALBUTAMOL SULPHATE IN METERED DOSE INHALERS: FORMULATION, CHARACTERIZATION AND IN VITRO EVALUATION

Objective: The present work was aimed to prepare niosomes entrapping salbutamol sulphate (SS) using reversed phase evaporation method (REV).Methods: Niosomes were prepared by mixing span 60 and cholesterol in 1:1 molar ratio in chloroform, SS in water was then added to organic phase to form niosomal SS. Formulations after evaporation of chloroform, freeze centrifuged then lyophilized, were evaluated for particles size, polydispersity index (Pdi), zeta-potential, morphology, entrapment efficiency (EE%) and in vitro release. For pulmonary delivery; metered dose inhalers (MDI) were prepared by suspending SS niosomes equivalent to 20 mg SS in hydrofluoroalkane (HFA). The metered valve was investigated for leakage rate, the total number of puffs/canister, weight/puff, dose uniformity and particle size.Results: The results showed spherical niosomes with 400-451 nm particles that entrapped 66.19% of SS. 76.54±0.132% SS release from niosomes that showed a controlled release profile for 8h. The leakage test was not exceeding 4 mg/3 d, the number of puffs were up to 200puffs/canister, the dose delivered/puff was 0.1 mg and 0.64-4.51μm niosomal aerosol.Conclusion: The results indicate an encouraging strategy to formulate a controlled drug delivery by entrapping (SS) in niosomes which could be packaged into (MDI) that met the requirements of (USP) aerosols guidelines which offering a novel approach to respiratory delivery

Locking-free two-layer Timoshenko beam element with interlayer slip

A new locking-free strain-based finite element formulation for the numerical treatment of linear static analysis of two-layer planar composite beams with interlayer slip is proposed. In this formulation, the modified principle of virtual work is introduced as a basis for the finite element discretization. The linear kinematic equations are included into the principle by the procedure, similar to that of Lagrangian multipliers. A strain field vector remains the only unknown function to be interpolated in the finite element implementation of the principle. In contrast with some of the displacement-based and mixed finite element formulations of the composite beams with interlayer slip, the present formulation is completely locking-free. Hence, there are no shear and slip locking, poor convergence and stress oscillations in these finite elements. The generalization of the composite beam theory with the consideration of the Timoshenko beam theory for the individual component of a composite beam represents a substantial contribution in the field of analysis of non-slender composite beams with an interlayer slip. An extension of the present formulation to the non-linear material problems is straightforward. As only a few finite elements are needed to describe a composite beam with great precision, the new finite element formulations is perfectly suited for practical calculations. (c) 2007 Elsevier B.V. All rights reserved

Behavior of FRP-strengthened RC elements subjected to pure shear

The shear behavior of fiber reinforced polymer strengthened reinforced concrete (FRP-strengthened RC) has been the focus of extensive research studies. However, the mechanism of this complex phenomenon has not been fully clarified. Recent analytical models which were developed for predicting the shear capacity of FRP strengthened RC girders were based on test results of simply supported beam specimens with various shear span-to-depth (a/d) ratios. In such tests no region of the specimen is subjected to uniform stress conditions, Therefore, the results of such tests cannot predict the true pure shear behavior due to non-uniformity of stresses, the presence of flexural and other non-shear related effects such as a/d ratio that cannot be filtered out. Therefore, proper design of shear strengthening using FRP requires testing of elements that are subjected to pure shear case primary before adding other governing effects. This allows a careful investigation and full understanding of the behavior at the element level. In order to accomplish this task, panel testing of representative RC specimens strengthened with FRP sheets were needed. This paper reports the testing of 10 FRP strengthened RC panels subjected to pure shear stress field. The tests were carried out to evaluate the effects of three variables: FRP stiffness, FRP wrapping scheme, and transverse steel reinforcement ratio. The test results showed that these three variables greatly affected the shear behavior due to various types of failure modes associated with FRP strengthening. In addition, it was observed that the magnitude of increased shear capacity associated with the application of FRP sheets depends not only upon the stiffness of FRP, but also on the stiffness of internal shear reinforcement. With the increase of internal steel shear reinforcement, the effectiveness of shear gain due to externally bonded FRP decreases

Streaming in-patient BPM data to the cloud with a real-time monitoring system

Monitoring the heart activities for old people or people with medical history (Arrhythmia or CHD) is targeted by most new medical technologies. This paper demonstrated an in-patient real-time monitoring system for heart rate estimation. A ratio of beats per minute (BPM) is continuously recorded, streamed and archived to the cloud via WeMos WiFi development board. This cost effective system is simply based on two sub-systems: BPM data acquisition through pulse sensor and WeMos-based communication systems. The streamed BPM data are saved instantaneously in Google drive as spreadsheets which can only be accessed by authorized persons wherever the internet service is available. Thus, the person in charge can remotely observe the patient’s status and do analytics for the archived data. A pilot study with eight subjects was carried out to validate the developed BPM tele-monitoring system. Encouraging results have been achieved

A Systematic Approach to Justifying Sufficient Confidence in Software Safety Arguments

Safety arguments typically have some weaknesses. To show that the overall confidence in the safety argument is considered acceptable, it is necessary to identify the weaknesses associated with the aspects of a safety argument and supporting evidence, and manage them. Confidence arguments are built to show the existence of sufficient confidence in the developed safety arguments. In this paper, we propose an approach to systematically constructing confidence arguments and identifying the weaknesses of the software safety arguments. The proposed approach is described and illustrated with a running example

Micromechanical based model for predicting aged rubber fracture properties

Environmental aging induces a slow and irreversible alteration of the rubber material’s macromolecular network. This alteration is triggered by two mechanisms which act at the microscale: crosslinking and chain scission. While crosslinking induces an early hardening of the material, chain scission leads to the occurrence of dangling chains responsible of the damage at the macromolecular scale. Consequently, the mechanical behavior as well as the fracture properties are affected. In this work, the effect of aging on the mechanical behavior up to fracture of elastomeric materials and the evolution of their fracture properties are first experimentally investigated. Further, a modeling attempt using an approach based upon a micro-mechanical but physical description of the aging mechanisms is proposed to predict the mechanical and fracture properties evolution of aged elastomeric materials. The proposed micro-mechanical model incorporates the concepts of residual stretch associated with the crosslinking mechanism and a so-called “healthy” elastic active chain (EAC) density associated with chain scission mechanism. The validity of the proposed approach is assessed using a wide set of experimental data either generated by the authors or available in the literature

Determination of the Loading Mode Dependence of the Proportionality Parameter for the Tearing Energy of Embedded Flaws in Elastomers Under Multiaxial Deformations

In this paper, the relationship between the tearing energy and the far-field cracking energy density (CED) is evaluated for an embedded penny-shaped flaw in a 3D elastomer body under a range of loading modes. A 3D finite element model of the system is used to develop a computational-based fracture mechanics approach which is used to evaluate the tearing energy at the crack in different multiaxial loading states. By analysing the tearing energy’s relationship to the far-field CED, the proportionality parameter in the CED formulation is found to be a function of stretch and biaxiality. Using a definition of biaxiality that gives a unique value for each loading mode, the proportionality parameter becomes a linear function of stretch and biaxiality. Tearing energies predicted through the resulting equation show excellent agreement to those calculated computationally

Non-linear analysis of two-layer timber beams considering interlayer slip and uplift

A new mathematical model and its finite element formulation for the non-linear analysis of mechanical behaviour of a two-layer timber planar beam is presented. A modified principle of virtual work is employed in formulating the finite element method. The basic unknowns are strains. The following assumptions are adopted in the mathematical model: materials are taken to be non-linear and can differ from layer to layer; interacting shear and normal contact tractions between layers are derived from the non-linear shear contact traction-slip and the non-linear normal contact traction-uplift characteristics of the connectors; the geometrically linear and materially non-linear Bernoulli's beam theory is assumed for each layer. The formulation is found to be accurate, reliable and computationally effective. The suitability of the theory is validated by the comparison of the numerical solution and the experimental results of full-scale laboratory tests on a simply supported beam. An excellent agreement between measured and calculated results is observed for all load levels. The further objective of the paper is the analysis of the effect of different normal contact traction-uplift constitutive relationships on the kinematic and static quantities in a statically determined and undetermined structure. While the shear contact traction-slip constitutive relationship dictates the deformability of the composite beam and has a substantial influence on most of the static and kinematic quantities of the composite beam, a variable normal contact traction-uplift constitutive relationship is in most cases negligible

A triangulated perspective for understanding CAM use in Lebanon: a qualitative study.

Background: Existing evidence marked a prevalent use of Complementary and Alternative Medicine (CAM) therapies in Lebanon that is concomitant with low rates of disclosure to health care providers and limited knowledge among the general public of safety and side effects of CAM use. Objectives: To examine the perspectives of Lebanese CAM users, CAM providers, and health care providers (HCPs) regarding their understanding of CAM and of the Push and Pull factors that drive its use. Methods: A qualitative research study was conducted using in-depth interviews, targeting Lebanese adults (CAM users; 18-65 years) (n=14), CAM providers such as yoga instructors, owners of CAM product outlets, herbalists, and religious figures (n=13); and HCPs including physicians, nurses, dietitians, and pharmacists (n=14). The topic guide covered, in addition to the understanding of CAM, the Push and Pull factors driving CAM use. The adults were recruited by convenient sampling, and CAM providers and HCPs using a purposive sampling approach. Interviews were audiotaped, transcribed, and translated into English. Analysis was performed using a qualitative thematic approach. Similarities and differences in the perceptions of the participants with regards to factors that influence CAM use were charted and contrasted, using a triangulated approach. Results: The three study groups exhibited a similar understanding of CAM, referring to non-conventional therapies used to prevent/treat diseases or to enhance wellbeing. CAM users and CAM providers identified "distrust in HCPs", "lack of patient-centered care in CM", and "limitations and side effects of CM" as important Push factors. All study groups highlighted the limited CAM knowledge of HCPs as a main reason for the lack of patient-centered care. All three groups also underscored the affordability and the social and cultural support for CAM as main enablers of its prevalent use. Unlike HCPs who were skeptical about the safety and effectiveness of CAM, CAM users and CAM providers indicated that most of CAM therapies are safe and efficient. Conclusions: The triangulation of perspectives (CAM users, CAM providers, and HCPs) in this study allowed a comprehensive appraisal of CAM use and its drivers. Improving the HCPs' CAM-related knowledge, promoting patient-centered care and fostering an open dialogue between HCPs and CAM providers are among the recommendations of the study. Background: Existing evidence marked a prevalent use of Complementary and Alternative Medicine (CAM) therapies in Lebanon that is concomitant with low rates of disclosure to health care providers and limited knowledge among the general public of safety and side effects of CAM use. Objectives: To examine the perspectives of Lebanese CAM users, CAM providers, and health care providers (HCPs) regarding their understanding of CAM and of the Push and Pull factors that drive its use. Methods: A qualitative research study was conducted using in-depth interviews, targeting Lebanese adults (CAM users; 18-65 years) (n=14), CAM providers such as yoga instructors, owners of CAM product outlets, herbalists, and religious figures (n=13); and HCPs including physicians, nurses, dietitians, and pharmacists (n=14). The topic guide covered, in addition to the understanding of CAM, the Push and Pull factors driving CAM use. The adults were recruited by convenient sampling, and CAM providers and HCPs using a purposive sampling approach. Interviews were audiotaped, transcribed, and translated into English. Analysis was performed using a qualitative thematic approach. Similarities and differences in the perceptions of the participants with regards to factors that influence CAM use were charted and contrasted, using a triangulated approach. Results: The three study groups exhibited a similar understanding of CAM, referring to non-conventional therapies used to prevent/treat diseases or to enhance wellbeing. CAM users and CAM providers identified "distrust in HCPs", "lack of patient-centered care in CM", and "limitations and side effects of CM" as important Push factors. All study groups highlighted the limited CAM knowledge of HCPs as a main reason for the lack of patient-centered care. All three groups also underscored the affordability and the social and cultural support for CAM as main enablers of its prevalent use. Unlike HCPs who were skeptical about the safety and effectiveness of CAM, CAM users and CAM providers indicated that most of CAM therapies are safe and efficient. Conclusions: The triangulation of perspectives (CAM users, CAM providers, and HCPs) in this study allowed a comprehensive appraisal of CAM use and its drivers. Improving the HCPs' CAM-related knowledge, promoting patient-centered care and fostering an open dialogue between HCPs and CAM providers are among the recommendations of the study