Model selection approaches for non-linear system identification: a review

The identification of non-linear systems using only observed finite datasets has become a mature research area over the last two decades. A class of linear-in-the-parameter models with universal approximation capabilities have been intensively studied and widely used due to the availability of many linear-learning algorithms and their inherent convergence conditions. This article presents a systematic overview of basic research on model selection approaches for linear-in-the-parameter models. One of the fundamental problems in non-linear system identification is to find the minimal model with the best model generalisation performance from observational data only. The important concepts in achieving good model generalisation used in various non-linear system-identification algorithms are first reviewed, including Bayesian parameter regularisation and models selective criteria based on the cross validation and experimental design. A significant advance in machine learning has been the development of the support vector machine as a means for identifying kernel models based on the structural risk minimisation principle. The developments on the convex optimisation-based model construction algorithms including the support vector regression algorithms are outlined. Input selection algorithms and on-line system identification algorithms are also included in this review. Finally, some industrial applications of non-linear models are discussed.

Inter-phyla studies on neuropeptides: the potential for broad-spectrum anthelmintic and/or endectocide discovery

Flatworm, nematode and arthropod parasites have proven their ability to develop resistance to currently available chemotherapeutics. The heavy reliance on chemotherapy and the ability of target species to develop resistance has prompted the search for novel drug targets. In view of its importance to parasite/pest survival, the neuromusculature of parasitic helminths and pest arthropod species remains an attractive target for the discovery Of novel endectocide targets. Exploitation of the neuropeptidergic system in helminths and arthropods has been hampered by a limited Understanding of the functional roles of individual peptides and the structure of endogenous targets, such as receptors. Basic research into these systems has the potential to facilitate target characterization and its offshoots (screen development and drug identification). Of particular interest to parasitologists is the fact that selected neuropeptide families are common to metazoan pest species (nematodes, platyhelminths and arthropods) and fulfil specific roles in the modulation of muscle function in each of the three phyla. This article reviews the inter-phyla activity of two peptide families, the FMRFamide-like peptides and allatostatins, on motor function in helminths and arthropods and discusses the potential of neuropeptide signalling as a target system that could uncover novel endectocidal agents.

An exploratory study of Principal Investigator roles in UK University Proof-of-Concept processes: an Absorptive capacity perspective

The increasing emphasis on academic entrepreneurship, technology transfer and research commercialisation within UK universities is predicated on basic research being developed by academics into commercial entities such as university spin-off companies or licensing arrangements. However, this process is fraught with challenges and risks, given the degree of uncertainty regarding future returns. In an attempt to minimise such risks, the Proof-of-Concept (PoC) process has been developed within University Science Park Incubators (USIs) to test the technological, business and market potential of embryonic technology. The key or the pivotal stakeholder within the PoC is the Principal Investigator (PI), who is usually the lead academic responsible for the embryonic technology. Within the current literature, there appears to be a lack of research pertaining to the role of the PI in the PoC process. Moreover, Absorptive Capacity (ACAP) has emerged within the literature as a theoretical framework or lens for exploring the development and application of new knowledge and technology, where the USI is the organisation considered in the current study. Therefore, the aim of this paper is to explore the role and influence of the PI in the PoC process within a USI setting using an ACAP perspective. The research involved a multiple case analysis of PoC applications within a UK university USI. The results demonstrate the role of the PI in developing practices and routines within the PoC process. These practices and processes were initially tacit and informal in nature but became more explicit and formal over time so that knowledge was retained within the USI after the PIs had completed the PoC process. © 2010 The Authors. R&D Management © 2010 Blackwell Publishing Ltd.

Lipoproteins and diabetic microvascular complications

Risk factors for the microvascular complications (nephropathy and retinopathy) of Type 1 and Type 2 diabetes mellitus and the associated accelerated atherosclerosis include: age, diabetes duration, genetic factors, hyperglycaemia, hypertension, smoking, inflammation, glycation and oxidative stress and dyslipoproteinaemia. Hypertriglyceridaemia, low HDL and small dense LDL are common features of Type 2 diabetes and Type 1 diabetes with poor glycaemic control or renal complications. With the expansion of knowledge and of clinical and research laboratory tools, a broader definition of 'lipid' abnormalities in diabetes is appropriate. Dyslipoproteinaemia encompasses alterations in lipid levels, lipoprotein subclass distribution, composition (including modifications such as non-enzymatic glycation and oxidative damage), lipoprotein-related enzymes, and receptor interactions and subsequent cell signaling. Alterations occur in all lipoprotein classes; chylomicrons, VLDL, LDL, HDL, and Lp(a). There is also emerging evidence implicating lipoprotein related genotypes in the development of diabetic nephropathy and retinopathy. Lipoprotein related mechanisms associated with damage to the cardiovascular system may also be relevant to damage to the renal and ocular microvasculature. Adverse tissue effects are mediated by both alterations in lipoprotein function and adverse cellular responses. Recognition and treatment of lipoprotein-related risk factors, supported by an increasing array of assays and therapeutic agents, may facilitate early recognition and treatment of high complication risk diabetic patients. Further clinical and basic research, including intervention trials, is warranted to guide clinical practice. Optimal lipoprotein management, as part of a multi-faceted approach to diabetes care, may reduce the excessive personal and economic burden of microvascular complications and the related accelerated atherosclerosis.

Dental erosion among 12-14 year old school children in Khartoum:A pilot study

Objectives: To investigate dental erosion among 12-14 year old Sudanese school children and evaluate the associated risk factors. Basic Research Design: Cross sectional survey in secondary schools in Khartoum city, Sudan. Method and Participants: A sample of 157 school children was obtained from both private and public schools. Erosion on the labial and palatal surfaces of maxillary incisors was measured by criterion based on the Smith and Knight Tooth Wear Index. Dietary intake and other related factors were assessed using a questionnaire. Results: The overall erosion prevalence in this group was 66.9%, of which 45.2% was mild and 21.7% was moderate erosion. A strong association was found between erosion and private schooling (higher socioeconomic groups), carbonated drinks, herbal hibiscus drink and traditional acidic food consumption. Conclusion: There was a high prevalence of dental erosion among Sudanese school children which was mild to moderate in severity and was strongly associated with acidic dietary intake © BASCD 2007.

Exendin-4 protects against post-myocardial infarction remodelling via specific actions on inflammation and the extracellular matrix

Glucagon-like peptide-1 (GLP-1) is an insulin-releasing hormone clinically exploited for glycaemic control in diabetes, which also confers acute cardioprotection and benefits in experimental/clinical heart failure. We specifically investigated the role of the GLP-1 mimetic, exendin-4, in post-myocardial infarction (MI) remodelling, which is a key contributor to heart failure. Adult female normoglycaemic mice underwent coronary artery ligation/sham surgery prior to infusion with exendin-4/vehicle for 4 weeks. Metabolic parameters and infarct sizes were comparable between groups. Exendin-4 protected against cardiac dysfunction and chamber dilatation post-MI and improved survival. Furthermore, exendin-4 modestly decreased cardiomyocyte hypertrophy/apoptosis but markedly attenuated interstitial fibrosis and myocardial inflammation post-MI. This was associated with altered extracellular matrix (procollagen IαI/IIIαI, connective tissue growth factor, fibronectin, TGF-β3) and inflammatory (IL-10, IL-1β, IL-6) gene expression in exendin-4-treated mice, together with modulation of both Akt/GSK-3β and Smad2/3 signalling. Exendin-4 also altered macrophage response gene expression in the absence of direct actions on cardiac fibroblast differentiation, suggesting cardioprotective effects occurring secondary to modulation of inflammation. Our findings indicate that exendin-4 protects against post-MI remodelling via preferential actions on inflammation and the extracellular matrix independently of its established actions on glycaemic control, thereby suggesting that selective targeting of GLP-1 signalling may be required to realise its clear therapeutic potential for post-MI heart failure.

Transport of laser accelerated proton beams and isochoric heating of matter

The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

An approach to determine the local boundary of small disturbance voltage stability region in a cut-set power space:基于微扰的割集电压稳定域局部边界求解方法

A new approach to determine the local boundary of voltage stability region in a cut-set power space (CVSR) is presented. Power flow tracing is first used to determine the generator-load pair most sensitive to each branch in the interface. The generator-load pairs are then used to realize accurate small disturbances by controlling the branch power flow in increasing and decreasing directions to obtain new equilibrium points around the initial equilibrium point. And, continuous power flow is used starting from such new points to get the corresponding critical points around the initial critical point on the CVSR boundary. Then a hyperplane cross the initial critical point can be calculated by solving a set of linear algebraic equations. Finally, the presented method is validated by some systems, including New England 39-bus system, IEEE 118-bus system, and EPRI-1000 bus system. It can be revealed that the method is computationally more efficient and has less approximation error. It provides a useful approach for power system online voltage stability monitoring and assessment. This work is supported by National Natural Science Foundation of China (No. 50707019), Special Fund of the National Basic Research Program of China (No. 2009CB219701), Foundation for the Author of National Excellent Doctoral Dissertation of PR China (No. 200439), Tianjin Municipal Science and Technology Development Program (No. 09JCZDJC25000), National Major Project of Scientific and Technical Supporting Programs of China During the 11th Five-year Plan Period (No. 2006BAJ03A06). ©2009 State Grid Electric Power Research Institute Press.

Exendin-4 attenuates adverse cardiac remodelling in streptozocin-induced diabetes via specific actions on infiltrating macrophages

In addition to its' established metabolic and cardioprotective effects, glucagon-like peptide-1 (GLP-1) reduces post-infarction heart failure via preferential actions on the extracellular matrix (ECM). Here, we investigated whether the GLP-1 mimetic, exendin-4, modulates cardiac remodelling in experimental diabetes by specifically targeting inflammatory/ECM pathways, which are characteristically dysregulated in this setting. Adult mice were subjected to streptozotocin (STZ) diabetes and infused with exendin-4/insulin/saline from 0 to 4 or 4-12 weeks. Exendin-4 and insulin improved metabolic parameters in diabetic mice after 12 weeks, but only exendin-4 reduced cardiac diastolic dysfunction and interstitial fibrosis in parallel with altered ECM gene expression. Whilst myocardial inflammation was not evident at 12 weeks, CD11b-F4/80(++) macrophage infiltration at 4 weeks was increased and reduced by exendin-4, together with an improved cytokine profile. Notably, media collected from high glucose-treated macrophages induced cardiac fibroblast differentiation, which was prevented by exendin-4, whilst several cytokines/chemokines were differentially expressed/secreted by exendin-4-treated macrophages, some of which were modulated in STZ exendin-4-treated hearts. Our findings suggest that exendin-4 preferentially protects against ECM remodelling and diastolic dysfunction in experimental diabetes via glucose-dependent modulation of paracrine communication between infiltrating macrophages and resident fibroblasts, thereby indicating that cell-specific targeting of GLP-1 signalling may be a viable therapeutic strategy in this setting.