Biaxial Yield for Nonlinearly Viscoelastic Materials with a Strain Clock

A constitutive equation with a dilatation dependent reduced time is used to model the mechanical response of solid amorphous polymers such as polycarbonate. Such constitutive equations have the property that stress relaxation occurs faster with increasing dilatation. In previous work, it has been shown that this constitutive equation can account for yield in materials undergoing uniaxial strain or stress control histories. In the present work, yield is discussed when materials described by this constitutive equation undergo homogeneous biaxial and triaxial strain histories. Four sets of conditions are considered: in-plane biaxial constant strain rate histories and in-plane biaxial constant stress rate histories, for both plane stress and plane strain states. Yield is defined in a manner analogous to that in the corresponding strain and stress control conditions in the uniaxial case.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43260/1/11043_2004_Article_185394.pd

Audit of head injury management in Accident and Emergency at two hospitals: implications for NICE CT guidelines

BACKGROUND: The National Institute for Clinical Excellence (NICE) has produced guidelines on the early management of head injury. This study audits the process of the management of patients with head injury presenting at Accident and Emergency (A&E) departments and examines the impact upon resources of introducing NICE guidelines for eligibility of a CT scan. METHODS: A retrospective audit of consecutive patients of any age, presenting at A&E with a complaint of head injury during one month in two northern District General Hospitals forming part of a single NHS Trust. RESULTS: 419 patients presented with a median age of 15.5 years, and 61% were male. 58% had a Glasgow Coma Score (GCS) recorded and 33 (8%) were admitted. Only four of the ten indicators for a CT scan were routinely assessed, but data were complete for only one (age), and largely absent for another (vomiting). Using just three (incomplete) indicators showed a likely 4 fold increase in the need for a CT scan. CONCLUSIONS: The majority of patients who present with a head injury to Accident and Emergency departments are discharged home. Current assessment processes and associated data collection routines do not provide the information necessary to implement NICE guidelines for CT brain scans. The development of such clinical audit systems in a busy A&E department is likely to require considerable investment in technology and/or staff. The resource implications for radiology are likely to be substantial

Fenton’s Oxidation of Personal Care Product (PCP) Wastewater: A Kinetic Study and the Effects of System Parameters

Personal care products (PCPs) are considered an emerging class of pollutants, and PCP wastewater is classified as hazardous because it contains organic compounds, which are linked to high chemical oxygen demand (COD) concentrations. PCP wastewater is dangerous when discharged into rivers without treatment, which entails oxidizing complex organic compounds into simpler compounds using advanced oxidation technology (AOT). Fenton’s reagent is composed of Fe2+ and H2O2 and can oxidize organic compounds, thus reducing COD concentrations. This study aims to determine the effectiveness of the AOT method by calculating COD removal in wastewater; analyze the effect of the Fe2+/H2O2 ratio, H2O2 concentration, and system pH; develop a kinetics model of COD reduction; and analyze the cost of PCP wastewater treatment. The parameters used in the study are Fe2+/H2O2 ratio, H2O2 concentration, and pH. The results of this study show that the highest level of COD removal was 88.59% at a Fe2+/H2O2 ratio of 9% w/w, a H2O2 concentration of six times the COD concentration, and a pH value of 3. The reaction followed pseudo-first-order reaction kinetics, and the reaction rate constant was 0.021 min?1. At a flow rate of 15 m3/day, which is applicable in an industrial site, the required reactor volume in a continuous system is less than that for a batch system. The required reactor volume for a plug flow reactor and a batch reactor are 1.625 m3 and 2.25 m3, respectively. The estimated cost to treat 1 liter of wastewater is IDR 1,385

The impact of diabetes-related complications on preference-based measures of health-related quality of life in adults with Type I diabetes

Introduction: This study estimates health-related quality of life (HRQoL) or utility decrements associated with type 1 diabetes mellitus (T1DM) using data from a UK research programme on the Dose Adjustment For Normal Eating (DAFNE) education programme. Methods: A wide range of data was collected from 2,341 individuals who undertook a DAFNE course in 2009-12, at baseline and for two subsequent years. We use fixed and random effects linear models to generate utility estimates for T1DM using different instruments: EQ-5D, SF-6D and EQ-VAS. We show models with and without controls for HbA1c and depression, which may be endogenous (if, for example, there is reverse causality in operation). Results: We find strong evidence of an unobserved individual effect, suggesting the superiority of the fixed effects model. Depression shows the greatest decrement across all the models in the preferred fixed effects model. The fixed effects EQ-5D model also finds a significant decrement from retinopathy, BMI and HbA1c(%). Estimating a decrement using the fixed effects model is not possible for some conditions where there are few new cases. In the random effects model diabetic foot disease shows substantial utility decrements, yet these are not significant in the fixed effects models. Conclusion: Utility decrements have been calculated for a wide variety of health states in T1DM which can be used in economic analyses. However, despite the large dataset, the low incidence of several complications leads to uncertainty in calculating the utility weights. Depression and diabetic foot disease result in a substantial loss in HRQoL for patients with T1DM. HbA1c(%) appears to have an independent negative impact upon HRQoL, although concerns remain regarding the potential endogeneity of this variable

Aquaporin-4 and brain edema.

Aquaporin-4 (AQP4) is a water-channel protein expressed strongly in the brain, predominantly in astrocyte foot processes at the borders between the brain parenchyma and major fluid compartments, including cerebrospinal fluid (CSF) and blood. This distribution suggests that AQP4 controls water fluxes into and out of the brain parenchyma. Experiments using AQP4-null mice provide strong evidence for AQP4 involvement in cerebral water balance. AQP4-null mice are protected from cellular (cytotoxic) brain edema produced by water intoxication, brain ischemia, or meningitis. However, AQP4 deletion aggravates vasogenic (fluid leak) brain edema produced by tumor, cortical freeze, intraparenchymal fluid infusion, or brain abscess. In cytotoxic edema, AQP4 deletion slows the rate of water entry into brain, whereas in vasogenic edema, AQP4 deletion reduces the rate of water outflow from brain parenchyma. AQP4 deletion also worsens obstructive hydrocephalus. Recently, AQP4 was also found to play a major role in processes unrelated to brain edema, including astrocyte migration and neuronal excitability. These findings suggest that modulation of AQP4 expression or function may be beneficial in several cerebral disorders, including hyponatremic brain edema, hydrocephalus, stroke, tumor, infection, epilepsy, and traumatic brain injury

The muscle protein dysferlin accumulates in the Alzheimer brain

Dysferlin is a transmembrane protein that is highly expressed in muscle. Dysferlin mutations cause limb-girdle dystrophy type 2B, Miyoshi myopathy and distal anterior compartment myopathy. Dysferlin has also been described in neural tissue. We studied dysferlin distribution in the brains of patients with Alzheimer disease (AD) and controls. Twelve brains, staged using the Clinical Dementia Rating were examined: 9 AD cases (mean age: 85.9 years and mean disease duration: 8.9 years), and 3 age-matched controls (mean age: 87.5 years). Dysferlin is a cytoplasmic protein in the pyramidal neurons of normal and AD brains. In addition, there were dysferlin-positive dystrophic neurites within Aβ plaques in the AD brain, distinct from tau-positive neurites. Western blots of total brain protein (RIPA) and sequential extraction buffers (high salt, high salt/Triton X-100, SDS and formic acid) of increasing protein extraction strength were performed to examine solubility state. In RIPA fractions, dysferlin was seen as 230–272 kDa bands in normal and AD brains. In serial extractions, there was a shift of dysferlin from soluble phase in high salt/Triton X-100 to the more insoluble SDS fraction in AD. Dysferlin is a new protein described in the AD brain that accumulates in association with neuritic plaques. In muscle, dysferlin plays a role in the repair of muscle membrane damage. The accumulation of dysferlin in the AD brain may be related to the inability of neurons to repair damage due to Aβ deposits accumulating in the AD brain

An Anti-Human ICAM-1 Antibody Inhibits Rhinovirus-Induced Exacerbations of Lung Inflammation

Human rhinoviruses (HRV) cause the majority of common colds and acute exacerbations of asthma and chronic obstructive pulmonary disease (COPD). Effective therapies are urgently needed, but no licensed treatments or vaccines currently exist. Of the 100 identified serotypes, ∼90% bind domain 1 of human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor, making this an attractive target for development of therapies; however, ICAM-1 domain 1 is also required for host defence and regulation of cell trafficking, principally via its major ligand LFA-1. Using a mouse anti-human ICAM-1 antibody (14C11) that specifically binds domain 1 of human ICAM-1, we show that 14C11 administered topically or systemically prevented entry of two major groups of rhinoviruses, HRV16 and HRV14, and reduced cellular inflammation, pro-inflammatory cytokine induction and virus load in vivo. 14C11 also reduced cellular inflammation and Th2 cytokine/chemokine production in a model of major group HRV-induced asthma exacerbation. Interestingly, 14C11 did not prevent cell adhesion via human ICAM-1/LFA-1 interactions in vitro, suggesting the epitope targeted by 14C11 was specific for viral entry. Thus a human ICAM-1 domain-1-specific antibody can prevent major group HRV entry and induction of airway inflammation in vivo

A timeband framework for modelling real-time systems

Complex real-time systems must integrate physical processes with digital control, human operation and organisational structures. New scientific foundations are required for specifying, designing and implementing these systems. One key challenge is to cope with the wide range of time scales and dynamics inherent in such systems. To exploit the unique properties of time, with the aim of producing more dependable computer-based systems, it is desirable to explicitly identify distinct time bands in which the system is situated. Such a framework enables the temporal properties and associated dynamic behaviour of existing systems to be described and the requirements for new or modified systems to be specified. A system model based on a finite set of distinct time bands is motivated and developed in this paper

Galaxy Harassment and the Evolution of Clusters of Galaxies

Disturbed spiral galaxies with high rates of star formation pervaded clusters of galaxies just a few billion years ago, but nearby clusters exclude spirals in favor of ellipticals. ``Galaxy harassment" (frequent high speed galaxy encounters) drives the morphological transformation of galaxies in clusters, provides fuel for quasars in subluminous hosts and leaves detectable debris arcs. Simulated images of harassed galaxies are strikingly similar to the distorted spirals in clusters at $z \sim 0.4$ observed by the Hubble Space Telescope.Comment: Submitted to Nature. Latex file, 7 pages, 10 photographs in gif and jpeg format included. 10 compressed postscript figures and text available using anonymous ftp from ftp://ftp-hpcc.astro.washington.edu/pub/hpcc/moore/ (mget *) Also available at http://www-hpcc.astro.washington.edu/papers