Verification of cardiac tissue electrophysiology simulators using an N-version benchmark

Ongoing developments in cardiac modelling have resulted, in particular, in the development of advanced and increasingly complex computational frameworks for simulating cardiac tissue electrophysiology. The goal of these simulations is often to represent the detailed physiology and pathologies of the heart using codes that exploit the computational potential of high-performance computing architectures. These developments have rapidly progressed the simulation capacity of cardiac virtual physiological human style models; however, they have also made it increasingly challenging to verify that a given code provides a faithful representation of the purported governing equations and corresponding solution techniques. This study provides the first cardiac tissue electrophysiology simulation benchmark to allow these codes to be verified. The benchmark was successfully evaluated on 11 simulation platforms to generate a consensus gold-standard converged solution. The benchmark definition in combination with the gold-standard solution can now be used to verify new simulation codes and numerical methods in the future.     

Intermediate band photovoltaics based on interband–intraband transitions using In0.53Ga0.47As/InP superlattice

We present a theoretical model to incorporate the quantum mechanism of two‐photon transitions into macroscopic operations. The two‐photon transition is described as a two‐step interband–intraband transition within the one‐band envelope‐function framework and is coupled with drift–diffusion as well as the potential distribution. In_0.53Ga_0.47As/InP superlattices (SLs) are chosen as the initial candidate to simulate intermediate band solar cell operation. In this type of structure, the absorption spectrum of interband and intraband transitions is asymmetric and strongly depends on device structure and operating conditions. Our results also reveal that the intraband transition dominates the detailed balance. Both the intermediate band (IB) configuration and the conversion efficiency are determined by the SL structure. Only well‐designed SLs can form the appropriate IB. Furthermore, an efficiency contour plot has been calculated to guide quantum design: the peak efficiency is 45.61% when the well thickness is 4 nm and the barrier thickness is 2 nm. As the well or barrier thickness increases to 10 nm, the absorption peak of the intraband transition gradually redshifts and narrows, so the efficiency correspondingly decreases to below 40%. Copyright © 2011 John Wiley & Sons, Ltd.     

Neuroprotective Effects of Liraglutide for Stroke Model of Rats

The number of diabetes mellitus (DM) patients is increasing, and stroke is deeply associated with DM. Recently, neuroprotective effects of glucagon-like peptide-1 (GLP-1) are reported. In this study, we explored whether liraglutide, a GLP-1 analogue exerts therapeutic effects on a rat stroke model. Wistar rats received occlusion of the middle cerebral artery for 90 min. At one hour after reperfusion, liraglutide or saline was administered intraperitoneally. Modified Bederson’s test was performed at 1 and 24 h and, subsequently, rats were euthanized for histological investigation. Peripheral blood was obtained for measurement of blood glucose level and evaluation of oxidative stress. Brain tissues were collected to evaluate the level of vascular endothelial growth factor (VEGF). The behavioral scores of liraglutide-treated rats were significantly better than those of control rats. Infarct volumes of liraglutide-treated rats at were reduced, compared with those of control rats. The level of derivatives of reactive oxygen metabolite was lower in liraglutide-treated rats. VEGF level of liraglutide-treated rats in the cortex, but not in the striatum significantly increased, compared to that of control rats. In conclusion, this is the first study to demonstrate neuroprotective effects of liraglutide on cerebral ischemia through anti-oxidative effects and VEGF upregulation.     

Trends in research foci in life science fields over the last 30 years monitored by emerging topics

We report here a simple method to identify the ‘emerging topics’ in life sciences. First, the keywords selected from MeSH terms on PubMed by filtering the terms based on their increment rate of the appearance, and, then, were sorted into groups dealing with the same topics by ‘co-word’ analysis. These topics were defined as ‘emerging topics’. The survey of the emerging keywords with high increment rates of appearance between 1972 to 2006 showed that emerging topics changed dramatically year by year, and that the major shift of the topics occurred in the late 90s; the topics that cover technical and conceptual aspects in molecular biology to the more systematic ‘-omics’-related and nanoscience-related aspects. We further investigated trends in emerging topics within various sub-fields in the life sciences.     

Structural Damage Detection Method Using Uncertain Frequency Response Functions

Abstract:   A structural damage detection method using uncertain frequency response functions (FRFs) is presented in this article. Structural damage is detected from the changes in FRFs from the original intact state. The measurements are always contaminated by noise, and sufficient data are often difficult to obtain; making it difficult to detect damage with a finite number of data. To surmount this, we introduce hypothesis testing based on the bootstrap method to statistically prevent detection errors due to measurement noise. The proposed method iteratively zooms in on the damaged elements by excluding the elements which were assessed as undamaged from among the damage candidates, step by step. The proposed approach was applied to numerical simulations using a 2D frame structure and its efficiency was confirmed.     

Familial Mediterranean fever and hyperimmunoglobulinemia D syndrome: two diseases with distinct clinical, serologic, and genetic features

OBJECTIVE: To determine whether the 2 periodic febrile syndromes familial Mediterranean fever (FMF) and hyperimmunoglobulinemia D syndrome (HIDS) are distinct diseases. METHODS: Clinical manifestations of the diseases were analyzed by physicians experienced with FMF and HIDS. Serum immunoglobulin (Ig) levels were studied in 70 patients with FMF using nephelometry or ELISA and compared with Ig levels in 50 patients with HIDS. Genetic linkage of HIDS with the chromosome 16 polymorphic locus RT70, currently used for refined localization of the FMF susceptibility gene (MEFV), was studied in 9 HIDS families (18 patients) using polymerase chain reaction amplification and gel electrophoresis. RESULTS: The main clinical features distinguishing FMF from HIDS were lymphadenectomy, skin eruption, and symmetrical oligoarthritis in HIDS, and monoarthritis, peritonitis, and pleuritis in FMF. Increased IgG levels were found in 12 patients with FMF (17%), IgA in 16 (23%), IgM in 9 (13%), and IgD in 9 (13%), significantly lower than the prevalence reported for HIDS. We found no evidence for genetic linkage between HIDS and the chromosome 16 marker RT70. CONCLUSION: HIDS and FMF are different entities, clinically, immunologically, and genetically.