bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenotypic flexibility of traits related to energy acquisition in mice divergently selected for basal metabolic rate (BMR)
Authors: Książek Aneta , Czerniecki Jan , Konarzewski Marek
Published: February 2009

Theoretical considerations suggest that one of the main factors determining phenotypic flexibility of the digestive system is the size (mass) of internal organs. To test this, we used mice from two lines selected for high and low levels of basal metabolic rate (BMR). Mice with higher BMRs also have larger internal organs and higher daily food consumption (C) under non-stressful conditions. We exposed animals from both lines to a sudden cold exposure by transferring them (without prior acclimation) from an ambient temperature of 23°C to 5°C. Cold exposure elicited a twofold increase in C and a 25%reduction of apparent digestive efficiency. For the same body mass-corrected C, small intestine, kidneys, heart and liver of cold-exposed low-BMR mice were smaller than those of the high-BMR line. Therefore, the internal organs of low-BMR animals were burdened with substantially higher metabolic loads(defined as C or digestible food intake per total mass of a particular organ). The mass-specific activity of citrate synthase (CS) in the liver and kidneys(but not heart) was also lower in the low-BMR mice. The magnitude of phenotypic flexibility of internal organ size and CS activity was strictly proportional to the organ mass (in the case of kidneys and liver, also mass-specific CS activity) prior to an increased energy demand. Thus,phenotypic flexibility had additive rather than multiplicative dynamics. Our results also suggest that variation in BMR positively correlates with the magnitude of an immediate spare capacity that fuels the initial response of internal organs to a sudden metabolic stress.
Freeze tolerance, supercooling points and ice formation: comparative studies on the subzero temperature survival of limno-terrestrial tardigrades
Authors: Hengherr S. , Worland M. R. , Reuner A. , Brümmer F. , Schill R. O.
Published: February 2009

Many limno-terrestrial tardigrades live in unstable habitats where they experience extreme environmental conditions such as drought, heat and subzero temperatures. Although their stress tolerance is often related only to the anhydrobiotic state, tardigrades can also be exposed to great daily temperature fluctuations without dehydration. Survival of subzero temperatures in an active state requires either the ability to tolerate the freezing of body water or mechanisms to decrease the freezing point. Considering freeze tolerance in tardigrades as a general feature, we studied the survival rate of nine tardigrade species originating from polar, temperate and tropical regions by cooling them at rates of 9, 7, 5, 3 and 1°C h–1 down to –30°C then returning them to room temperature at 10°C h–1. The resulting moderate survival after fast and slow cooling rates and low survival after intermediate cooling rates may indicate the influence of a physical effect during fast cooling and the possibility that they are able to synthesize cryoprotectants during slow cooling. Differential scanning calorimetry of starved, fed and cold acclimatized individuals showed no intraspecific significant differences in supercooling points and ice formation. Although this might suggest that metabolic and biochemical preparation are non-essential prior to subzero temperature exposure, the increased survival rate with slower cooling rates gives evidence that tardigrades still use some kind of mechanism to protect their cellular structure from freezing injury without influencing the freezing temperature. These results expand our current understanding of freeze tolerance in tardigrades and will lead to a better understanding of their ability to survive subzero temperature conditions.
Hemoglobin enhances oxygen uptake in larval zebrafish (Danio rerio) but only under conditions of extreme hypoxia
Authors: Rombough Peter , Drader Holly
Published: February 2009

The role of hemoglobin (Hb) in O2 uptake by zebrafish larvae ranging in age from 5 to 42 days postfertilization was assessed under conditions of normoxia, moderate hypoxia and extreme hypoxia. This was achieved by exposing larvae with and without functional Hb to continuously declining oxygen levels (PO2) in closed-system respirometers. Exposure to 5% CO for 2–4 h was used to render Hb effectively non-functional in terms of its ability to transport O2. Routine metabolic rate(rṀO2), critical dissolved oxygen level (Pc) and residual oxygen level(Pr) were determined and used, respectively, as indicators of response in normoxia, moderate hypoxia and extreme hypoxia. rṀO2 was defined as the average rate of O2 uptake before O2 became limiting (i.e. at high PO2s). Pc is the PO2 at which rṀO2 first becomes O2-limited and Pr is the PO2 below which larvae are no longer able to extract O2 from the ambient medium. CO poisoning had no significant impact on rṀO2 or Pc at any age, indicating that the lack of functional Hb does not impair routine O2 usage in normoxia or at moderate levels of hypoxia [down to at least 25–50 torr (1 torr≈0.133 kPa), depending on age]. Pr, however, was significantly lower overall for control larvae (6.7±1.1 torr; mean ± 95%CI) than for CO-poisoned larvae (11.2±2.1 torr). It would appear that the presence of functional Hb allows zebrafish larvae to extract O2 from water down to lower PO2s under conditions of extreme hypoxia. This is the first documented (as opposed to inferred) benefit of Hb in developing zebrafish. However, given the relatively small magnitude of the effect it is unclear if this benefit on its own is sufficient to balance the costs associated with Hb production and maintenance.
Forecasting Residential Consumption of Natural Gas Using Genetic Algorithms
Authors: Aras Nil
Published: February 2009

This paper presents an application of genetic algorithms to forecast short-term demand of natural gas in residences. Residential demand is assumed to be a function of time, heating degree-day value, and consumer price index. A genetic algorithm is designed to estimate parameters of a multiple nonlinear regression model which mathematically represents the relationship between natural gas consumption and influential variables. Genetic algorithms have recently received attention as robust stochastic search algorithms to solve various forecasting problems since they have several significant advantages over conventional methods. Without requiring assumptions need to be made about the underlying function or model, genetic algorithms can attain proper solutions by scanning solution space from many different starting point. To show the applicability and superiority of the described approach, it is considered the monthly data of the residential sector which consumes 23% of imported natural gas in Turkey. The results have revealed that genetic algorithms can be used as an alternative solution approach to forecast the future demand of natural gas.
Experimental Study on Pyrolysis of Black Alder Wood
Authors: Balat Mustafa
Published: February 2009

The aim of this study is to obtain liquid, solid and gaseous products from pyrolysis of black alder wood (Alnus glutinosa). Yield of products resulting from biomass pyrolysis can be maximized as follows: i) charcoal — a low temperature, low heating rate process; ii) liquid products — a low temperature, high heating rate, short gas residence time process; and iii) fuel gas — a high temperature, low heating rate, long gas residence time process. The most interesting temperature range for the production of the pyrolysis products is between 625 and 775 K. In this study, the highest liquid yields were obtained from pyrolysis of black alder wood between 570 and 690 K. The yield of conversion of black alder wood reached the maximum 71.3 wt% at 775 K
Simulation of the Decomposition of Natural Gas Hydrate in Porous Media by Hot Water Injection
Authors: Zhou Xitang , Tao Xianhua , Liang Deqing , Fan Shuanshi
Published: February 2009

As a reference of the recovery of natural gas hydrates by hot water injection, the decomposition of natural gas hydrates in sediments due to heat stimulation was simulated experimentally and numerically. It is supposed the radial diffusion model describes the decomposition of natural gas hydrates in sediments owing to hot water injection, and the hydrate decomposition is a one-order reaction. Combining the rate equation of the decomposing reaction with the rate equation of the heat transfer and heat balance equation, the relationship between the accumulative quantity of methane (no-nH) and decomposing time t was obtained i.e., ie. By comparing the results from the experiment and numerical simulation, it was found that, under the experimental conditions, the rate coefficient of hydrate decomposition was 2.675×10−4 mol/(m2.Pa.min), which was found to be consistent with the experimental results.
Water Vapour Adsorption of Microporous Carbon Films Prepared from Fluorinated Aromatic Polyimides
Authors: Ohta Naoto , Nishi Yoko , Morishita Takahiro , Tojo Tetsuro , Inagaki Michio
Published: February 2009

The adsorption of water vapour onto microporous carbon films derived from fluorinated aromatic polyimides was studied at 25°C over the relative pressure range 0–0.95. The carbon films prepared were microporous with a high micropore volume ranging up to 0.44 ml/g and a sharp pore-width distribution at ca. 0.6 nm.

The adsorption/desorption isotherm of water vapour onto the carbon films was of type V with slight hysteresis. The carbon films derived from fluorinated polyimides were found to exhibit a much higher water vapour adsorption at low relative pressure regions relative to commercially available activated carbon fibres, with their saturated adsorption capacities being dependent on their micropore volumes. The microporous carbon derived from the polyimide with the highest fluorine content (31.3 mass%) showed the highest saturated adsorption capacity of ca. 465 mg/g, with 90 mass% of the water vapour being adsorbed at a relative pressure below 0.46. Both the high micropore volume and the high water vapour adsorption were maintained even after heat treatment at 1300°C, although the steep uptake of water vapour was shifted to higher relative pressures to some extent.
The Adsorption of Zn(II) Ions onto Chitin: Determination of Equilibrium, Kinetic and Thermodynamic Parameters
Authors: Kocer N. Nacer , Uslu G. , Cuci Y.
Published: February 2009

The adsorption of zinc(II) ions from aqueous solutions onto chitin was investigated as a function of the initial pH, temperature and initial metal ion concentration of the solutions concerned. The highest Zn(II) ion adsorption capacity was determined as 8.21 mg/g for an initial Zn(II) ion concentration of 300 mg/l at a pH value of 4.5 at 40°C. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium and isotherm constants were evaluated at different temperatures. The adsorption data were well described by the Langmuir equation although they could also be modelled by the Freundlich equation. The thermodynamics constants AG0, AH0 and AS0 for the adsorption process were evaluated as −19.73 kJ/mol (at 40°C), 4.13 kJ/mol and 0.076 kJ/(mol K), respectively. These values show that the adsorption of Zn(II) ions onto chitin was both endothermic and spontaneous.
Adsorption Equilibria of Natural Gas Components on Activated Carbon: Pure and Mixed Gas Isotherms
Authors: Bazan R.E. , Bastos-Neto M. , Staudt R. , Papp H. , Azevedo D.C.S. , Cavalcante C.L.
Published: February 2009

A typical Natural Gas (NG) composition in South America contains ca. 86% methane, 10% ethane, 1.5% carbon dioxide, 1% nitrogen and other heavier hydrocarbons. The composition plays an important role in studies of NG storage systems since heavier alkanes may accumulate in the adsorbent bed, saturate it in long-term use and affect the storage capacity. In this study, measurements of experimental data for the adsorption equilibria of binary mixtures of CH4 with C2H6, CO2, C3H8 and N2 — as obtained in a volumetric/chromatographic set-up — are presented and compared with mathematical models for multi-component adsorption based on pure component adsorption data. Experimental results were compared with predictions from the Extended Langmuir (EL) model and the Ideal Adsorbed Solution Theory (IAST) model. The IAST model was capable of providing a more accurate fit to most of the obtained data, other than those measured for the least adsorbed gases (CH4/N2).
Removal of Aniline from Waste Streams Using a Combined Adsorption and Catalytic Oxidation Approach
Authors: O'Brien J. , Curtin T. , O'Dwyer T.F.
Published: February 2009

The focus of the work described was the development of a solid catalytic adsorbent material capable of being regenerated, with the ability of adsorbing aniline from aqueous solution and the subsequent catalytic oxidation of the adsorbed aniline.

Initially, an H-ZSM-5 zeolite was loaded with copper via an ion-exchange process to enhance its catalytic activity. Experimental results indicated an aniline adsorption level of ca. 37–42 mg/g for each of the unmodified H-ZSM-5, the 0.5 w/w% Cu–ZSM-5 or the 1.4 w/w% Cu–ZSM-5 zeolites. The Langmuir adsorption model was applicable to all aniline-on-zeolite adsorption processes, with the level of aniline adsorbed being largely unaffected by a change in temperature. The kinetics of the adsorption processes, indicated that the maximum uptake of aniline occurred within 50 min of contact. Assessment of the aqueous stability of the exchanged copper on the ZSM-5 zeolites indicated minimum copper leaching within the pH range 5–11, thus providing a stable working pH range for both the 0.5 w/w% and 1.4 w/w% Cu–ZSM-5 adsorbent materials.

Catalytic oxidation studies on the adsorbed aniline indicated that the presence of copper in the zeolites significantly enhanced the degradation of aniline to predominantly carbon dioxide, water and nitrogen, with the production of significantly smaller levels of nitrogen oxide, benzene and nitrogen dioxide.
Characterizing Wind Power Forecast Uncertainty with Numerical Weather Prediction Spatial Fields
Authors: Cutler Nicholas J. , Kepert Jeffrey D. , Outhred Hugh R. , MacGill Iain F.
Published: February 2009

Successful integration of wind power into power systems can be facilitated through better understanding of future uncertainty in wind power generation. This paper explores a new approach to characterizing this uncertainty using measures of the variability in the wind speeds predicted at multiple grid points in a Numerical Weather Prediction (NWP) system. This approach is compared to the traditional approach of using the spread from an NWP ensemble by using two measures of uncertainty; forecast errors in single time-series forecasts and observed temporal variability. Results show that the multiple grid point approach has a comparable skill level to NWP ensembles for predicting these uncertainty measures and in particular, demonstrates very good skill in predicting large forecast errors. These results also provide a positive evaluation of a terrain standardization method described in a companion paper. A possible extension of this work is to combine the multiple grid point approach with NWP ensembles to improve uncertainty characterization.
Digital Control of a Wind Turbine Supplying an Isolated Load in Cooperation with a Hydro Power Unit
Authors: Schinas N. , Vovos N. A.
Published: February 2009

This paper presents different discrete control strategies for a variable speed pitch-controlled wind turbine (WT) which supplies an autonomous system in cooperation with a small hydro power unit. The WT consists of a synchronous generator (SG) with two three-phase stator windings displaced by 300, so as the torque distortions due to the wind fluctuations to be limited. The SG operates in variable speed mode in order to maximize the power absorbed from the wind and minimize the amount of water consumed by the hydro power unit. The requirements from the control schemes are to deliver the total power from the WT to the isolated load under constant voltage and frequency and adjust suitably the power from the hydro unit at the same time. There are two controllers: the rectifier controller, which drives the WT at such value of mechanical velocity that maximum power from the wind is absorbed and the inverter controller, which passes this amount of power to the load under constant voltage. There are two schemes presented in this paper: the first includes two PID controllers and the second includes a robust controller for the rectifier pulsation and a state-feedback controller for the inverter pulsation.
Developments of Cold-Formed Steel Sections in Composite Applications for Residential Buildings
Authors: Lawson R. M. , Ogden R. G. , Pedreschi R. , Popo-Ola S. O.
Published: February 2009

Cold-formed steel sections are often designed and built to act compositely with other constructional materials, particularly with wood and cementitious materials in order to improve their structural performance. This paper reviews some recent developments in composite applications of cold-formed steel sections in the U.K., and presents a number of design recommendations for these forms of structures in residential buildings.
Recent Development of Deployable Tension-Strut Structures
Authors: Liew J. Y. Richard , Vu K. K. , Krishnapillai A.
Published: February 2009

This paper presents the latest development of Deployable Tension-Strut Structures (DTTSs), which can be assembled quickly to save construction time while the structural efficiency is maintained to be as good as that of conventional double-layer space frames. Pre-tensioning techniques are used to enhance the structural stiffness and stability of the structure after it is “locked” to its final configuration. The design concept is explained in details with four illustrative examples and the structural efficiency of the proposed systems is investigated by using advanced non-linear analysis and free-vibration analysis. Novel moveable pin-jointed system has been developed to allow deployment of the tension-strut structures. Full scale prototype is built to demonstrate the buildability and deployability of the proposed systems. The results conclude that the proposed structures are structural effective, lightweight and can be easily deployable for spatial enclosure.
Advances in Analysis and Design of Cold-Formed Steel Structures
Authors: Chung K. F. , Ho H. C. , Wang A. J. , Yu W. K.
Published: February 2009

This paper summarizes a number of recent experimental and numerical investigations into the structural behaviour of cold-formed steel structures with bolted connections conducted by the authors, and all of them focus on the efficient use of bolted moment connections between cold-formed steel sections. It aims to present the latest analysis and design techniques as well as some practical design guidance and considerations on the overall performance of cold-formed steel structural systems. Hence, researchers and designers are encouraged to exploit the structural benefits offered by cold-formed steel structures with practical and efficient moment framing in building construction.
A Theoretical Basis for Identifying the Sound Sources in a Turbulent Flow
Authors: Goldstein M. E.
Published: February 2009

A space-time filtering approach is used to divide an unbounded turbulent flow into its radiating and non-radiating components. The result is then used to clarify a number of issues including the possibility of identifying the sources of the sound in such flows. It is also used to investigate the efficacy of some of the more recent computational approaches.
Turbulence and Sound-Field POD Analysis of a Turbulent Jet
Authors: Freund J. B. , Colonius T.
Published: February 2009

A Proper Orthogonal Decomposition (POD) is constructed for a Mach 0.9 turbulent jet using a well-validated direct numerical simulation database. Norms are defined based on near-field volume integrals of pressure, turbulence kinetic energy, streamwise velocity, and total enthalpy, two-dimensional integrals of streamswise velocity (to match experimental measurements), and far-field integrals of pressure over a sphere. We find substantially different POD modes for the different norms, and their efficiency at representing the full data is strongly dependent upon the norm and specifically which data we attempt to represent. To reproduce near-field turbulence statistics requires relatively few modes computed by a kinetic energy or pressure norm. However, a large number of the POD modes computed using a near-field norm are required to represent the sound field. The dominant near-field POD modes computed with either the near-field pressure norm or the sound field norm have the structure of wave packets.
A Note on Noise Generation by Large Scale Turbulent Structures in Subsonic and Supersonic Jets
Authors: Morris Philip J.
Published: February 2009

This paper describes a method to connect the measured spectral density in the acoustic far field with the wavenumber/frequency spectrum of the near field fluctuations that produce the noise. A relationship is first derived between the far field spectral density and the wavenumber/frequency spectrum of the pressure fluctuations on a cylindrical surface surrounding the jet in the near field. Measurements of the far field spectral density are then decomposed into contributions from the Large Scale Similarity (LSS) and Fine Scale Similarity (FSS) spectra. The near field wavenumber/frequency spectrum associated with the LSS spectral density alone is then determined. It is shown to have a very similar form for a range of jet operating conditions and Strouhal numbers. This form is consistent with an instability wave or wave packet model. Since both subsonic and supersonic jet exit conditions are examined, it is argued that the noise radiation in the peak radiation directions is controlled by the axial evolution of the turbulent large scale structures and is not associated with a combination of source convection and mean flow refraction effects.
Research Note—Information Technology in Supply Chains: The Value of IT-Enabled Resources Under Competition
Authors: Dong Shutao , Xu Sean Xin , Zhu Kevin Xiaoguo
Published: February 2009

In this study, we seek to better understand the value of information technology (IT) in supply chain contexts. Grounded in the resource-based theory in conjunction with transaction cost economics, we develop a conceptual model that links three IT-related resources (backend integration, managerial skills, and partner support) to firm performance improvement. The model differs from previous studies by proposing a moderating effect of competition on the resource-performance relationships. Using data of 743 manufacturing firms, our analysis indicates significant contribution of IT to supply chains, which is generated through development of the digitally enabled integration capability and manifested at the process level along the supply chain. The technological resource alone, however, does not hold the answer to IT value creation. In fact, managerial skills, which enable adaptations on supply chain processes and corporate strategy to accommodate the use of IT, are shown to play the strongest role in IT value creation. Furthermore, backend integration and managerial skills are found to be more valuable in more competitive environments. While commodity-like resources have diminishing value under competition, integrational and managerial resources become even stronger. Overall, our results shed light on the key drivers of IT-enabled supply chains, and provide insights into how competition shapes IT value.
Portfolio Selection with Robust Estimation
Authors: DeMiguel Victor , Nogales Francisco J.
Published: February 2009

Mean-variance portfolios constructed using the sample mean and covariance matrix of asset returns perform poorly out of sample due to estimation error. Moreover, it is commonly accepted that estimation error in the sample mean is much larger than in the sample covariance matrix. For this reason, researchers have recently focused on the minimum-variance portfolio, which relies solely on estimates of the covariance matrix, and thus usually performs better out of sample. However, even the minimum-variance portfolios are quite sensitive to estimation error and have unstable weights that fluctuate substantially over time. In this paper, we propose a class of portfolios that have better stability properties than the traditional minimum-variance portfolios. The proposed portfolios are constructed using certain robust estimators and can be computed by solving a single nonlinear program, where robust estimation and portfolio optimization are performed in a single step. We show analytically that the resulting portfolio weights are less sensitive to changes in the asset-return distribution than those of the traditional portfolios. Moreover, our numerical results on simulated and empirical data confirm that the proposed portfolios are more stable than the traditional minimum-variance portfolios, while preserving (or slightly improving) their relatively good out-of-sample performance.
Bounds for Maximin Latin Hypercube Designs
Authors: van Dam Edwin R. , Rennen Gijs , Husslage Bart
Published: February 2009

Latin hypercube designs (LHDs) play an important role when approximating computer simulation models. To obtain good space-filling properties, the maximin criterion is frequently used. Unfortunately, constructing maximin LHDs can be quite time consuming when the number of dimensions and design points increase. In these cases, we can use heuristical maximin LHDs. In this paper, we construct bounds for the separation distance of certain classes of maximin LHDs. These bounds are useful for assessing the quality of heuristical maximin LHDs. Until now only upper bounds are known for the separation distance of certain classes of unrestricted maximin designs, i.e., for maximin designs without a Latin hypercube structure. The separation distance of maximin LHDs also satisfies these “unrestricted” bounds. By using some of the special properties of LHDs, we are able to find new and tighter bounds for maximin LHDs. Within the different methods used to determine the upper bounds, a variety of combinatorial optimization techniques are employed. Mixed-integer programming, the traveling salesman problem, and the graph-covering problem are among the formulations used to obtain the bounds. Besides these bounds, also a construction method is described for generating LHDs that meet Baer's bound for the ℓ∞ distance measure for certain values of n.
Typical intellectual engagement, Big Five personality traits, approaches to learning and cognitive ability predictors of academic performance
Authors: Furnham Adrian , Monsen Jeremy , Ahmetoglu Gorkan
Published: February 2009

Background Both ability (measured by power tests) and non‐ability (measured by preference tests) individual difference measures predict academic school outcomes. These include fluid as well as crystalized intelligence, personality traits, and learning styles. This paper examines the incremental validity of five psychometric tests and the sex and age of pupils to predict their General Certificate in Secondary Education (GCSE) test results.

Aims The aim was to determine how much variance ability and non‐ability tests can account for in predicting specific GCSE exam scores.

Sample The sample comprised 212 British schoolchildren. Of these, 123 were females. Their mean age was 15.8 years (SD 0.98 years).

Method Pupils completed three self‐report tests: the Neuroticism–Extroversion–Openness‐Five‐Factor Inventory (NEO‐FFI) which measures the ‘Big Five’ personality traits, (Costa & McCrae, 1992); the Typical Intellectual Engagement Scale (Goff & Ackerman, 1992) and a measure of learning style, the Study Process Questionnaire (SPQ; Biggs, 1987). They also completed two ability tests: the Wonderlic Personnel Test (Wonderlic, 1992) a short measure of general intelligence and the General Knowledge Test (Irving, Cammock, & Lynn, 2001) a measure of crystallized intelligence. Six months later they took their (10th grade) GCSE exams comprising four ‘core’ compulsory exams as well as a number of specific elective subjects.

Results Correlational analysis suggested that intelligence was the best predictors of school results. Preference test measures accounted for relatively little variance. Regressions indicated that over 50% of the variance in school exams for English (Literature and Language) and Maths and Science combined could be accounted for by these individual difference factors.

Conclusions Data from less than an hour's worth of testing pupils could predict school exam results 6 months later. These tests could, therefore, be used to reliably inform important decisions about how pupils are taught.
Management of Gene Promoter Mutations in Molecular Diagnostics
Authors: de Vooght Karen M K , van Wijk Richard , van Solinge Wouter W
Published: February 2009

Background: Although promoter mutations are known to cause functionally important consequences for gene expression, promoter analysis is not a regular part of DNA diagnostics.

Content: This review covers different important aspects of promoter mutation analysis and includes a proposed model procedure for studying promoter mutations. Characterization of a promoter sequence variation includes a comprehensive study of the literature and databases of human mutations and transcription factors. Phylogenetic footprinting is also used to evaluate the putative importance of the promoter region of interest. This in silico analysis is, in general, followed by in vitro functional assays, of which transient and stable transfection assays are considered the gold-standard methods. Electrophoretic mobility shift and supershift assays are used to identify trans-acting proteins that putatively interact with the promoter region of interest. Finally, chromatin immunoprecipitation assays are essential to confirm in vivo binding of these proteins to the promoter.

Summary: Although promoter mutation analysis is complex, often laborious, and difficult to perform, it is an essential part of the diagnosis of disease-causing promoter mutations and improves our understanding of the role of transcriptional regulation in human disease. We recommend that routine laboratories and research groups specialized in gene promoter research cooperate to expand general knowledge and diagnosis of gene-promoter defects.
Social Welfare in Singapore and Sweden: Differences in Organisational Systems of Health Care, Social Security and Rehabilitation
Authors: Olsson Inger , Millet Patrick , Vinberg Stig , Olsson Göran , Bergroth Alf , Landstad Bodil J.
Published: February 2009

The aim of the study is to describe and compare the health care, social security and rehabilitation systems in Singapore and Sweden. Two fundamental differences can be identified. First, the system in Singapore are strongly oriented towards a free market system, while Sweden's demonstrates strong public control. Second, following from how the systems are oriented, Singaporeans are expected to have a higher degree of independence and control over their health care, social security and rehabilitation. It appears that Singapore has had greater success in attaining and maintaining a system of health promotion, which influences the three systems. However, the Swedish welfare system provides greater security to those who are in need of health care, social security and rehabilitation.
Collaborating With Physicians to Redesign a Sign-Out Tool
Authors: Devoge Justin M. , Bass Ellen J. , Sledd Richard M. D. , Borowitz Stephen M. , Waggoner-Fountain Linda
Published: February 2009

Physician sign-out is a mechanism for transferring patient information from one group of hospital care-givers to another at shift changes. Support tools are critical to the success of sign-out. To ensure that a tool is effective, designers must collaborate with end users, but collaboration can be difficult when working with users who are busy and have irregular schedules. In this article, we report on a collaborative effort between physicians and engineers to redesign a sign-out support tool. Strategies included focus groups, interviews, “on-the-fly” feedback, and an iterative design process, which engaged end users in the design process. Task analysis methods enabled us to quantify the differences in functionality between the original tool and the prototype.
A Physics-Based Predictive Model for Fracture Toughness Behavior
Authors: Natishan ME , Wagenhofer M , Rosinski ST
Published: February 2009

Using the Zerilli-Armstrong (ZA) constitutive model for BCC materials and a combined strength-strain model of fracture, a physics model suitable for predicting the fracture toughness transition behavior of ferritic steels has been developed. The model predicts an exponential dependence of the plastic work on temperature and thus is comparable to the exponential dependence of plastic work predicted by Wallin et al. for the Master Curve. Exploring the limits of applicability of the ZA equation used as the basis for this model provides the information required to firmly establish the limits of material condition applicability of the Master Curve. Calculations based on limited data provide validation of the proposed model. The models' ability to predict shifts in transition temperature with irradiation and its application to RP vessel integrity assessment will also be discussed.
Transferability Properties of Local Approach Modeling in the Ductile to Brittle Transition Region
Authors: Laukkanen A , Wallin K , Nevasmaa P , Tähtinen S
Published: February 2009

Qualitative descriptive potential of local approach models for upper shelf and transition region has been well established. Models such as the Gurson-Tvergaard-Needleman and the Beremin model have been demonstrated to enable characterization of fracture phenomena over the entire transition regime. The foundation for consistent local approach characterization of material failure has been set, but quantitative application is still at developing stages. Current work addresses properties of a modified Beremin model in terms of material parameter consistency and transferability, which are taken as measures of performance with respect to quantitative applicability. Three-point bend specimen fracture toughness data of sizes 3×4×27 mm, 5×5×27 mm, 5×10×55 mm and 10×10×55 mm are simulated in the ductile to brittle transition region using finite element methods and inference of local approach parameters is performed using pointwise collocation and stochastic methods. The suitability of the calibration methods and overall model performance are evaluated and demonstrated.
Image-Based Characterization and Finite Element Analysis of Porous SMA Behavior
Authors: Qidwai MA , DeGiorgi VG , Everett RK
Published: February 2009

Porous shape memory alloys (SMAs) are a relatively new group of materials that are of interest because of their potential use in the design of damping and shock mitigation systems. Benefits of the material include reduced weight, high level of energy absorption through phase transformation and possible increased energy absorption through wave scattering due to porosity. Essential to the use of these materials is an understanding of the structural and shock absorbing response of the material. Constitutive models that accurately represent these characteristics are necessary. The emphasis of this research is to develop a computational methodology that will bridge the mesostructural and macrostructural features of porous SMAs. The first step in the process involves the detailed characterization of the relevant mesostructure, i.e., information about pore shape, size, volume fraction and distribution. This representative characterization can be used to produce realistic image-based finite element models. Because the resultant models have large degrees of freedom they cannot be employed to analyze large-scale structural problems. However, simply designed boundary value problems such as the dynamic uniaxial compressive loading of a bar can be used as benchmarks for the verification of phenomenological macro-constitutive models, or models that are derived using averaging methods such as the Mori-Tanaka method or the self-consistent method. In this study, an attempt is made to analyze numerically porous SMA behavior under dynamic conditions based on the representative mesostructural features. Preliminary results are obtained for selected pore volume fractions and distinct trends in material behavior are observed.
Generalized Size and Shape Description of UHMWPE Wear Debris — A Comparison of Cross-Linked, Enhanced Fused, and Standard Polyethylene Particles
Authors: Sprecher CM , Schneider E , Wimmer MA
Published: February 2009

Released wear debris of implants causes local inflammation of the host tissue if it is in a phagocytosable size. The purpose of this study was to compare particle size, shape, and number of three different types of UHMWPE. After wear testing, particles were isolated from the serum and analyzed using SEM. The parameters ‘equivalent circle diameter’ (ECD) and ‘equivalent shape ratio’ (ESR) were determined. Most of the generated debris was sub-micron in size. Classifying the particles into size groups demonstrated a non-linear correlation between size and shape for all three types of polyethylene: small particles were more round, large particles were more elongated. Based on this relationship, the generated number of particles and their total surface area were estimated and compared with calculations based on size alone.
Development of a Model for Testing Third Body Wear of UHMWPE Acetabular Components
Authors: Bragdon CR , O'Connor D , Muratoglu OK , Harris WH
Published: February 2009

The purpose of this paper is to describe the development of a new wear test protocol utilizing third body particulate debris in order to assess conventional and highly cross-linked polyethylene components. A series of tests were performed using the Boston Hip Simulator to evaluate different types of particles for possible use. Modifications to the simulator are described which ensure that the third body particles can be maintained in suspension. In this series of studies, alumina particles in a concentration of 0.15mg/cc appeared to provide the most effective challenge to the wear resistance of UHMWPE while at the same time not creating unrealistic destruction to the femoral head. In all of the experiments, under all conditions, the WIAM highly crosslinked polyethylene acetabular components resisted the effects of the third body particles and the concomitant changes in the femoral heads distinctly better than the conventional UHMWPE.
The Effects of Raw Material, Irradiation Dose, and Irradiation Source on Crosslinking of UHMWPE
Authors: Greer KW , King RS , Chan FW
Published: February 2009

Four Ultra-High Molecular Weight Polyethylene (UHMWPE) materials were evaluated after various irradiation crosslinking processes to determine the effects of the materials and processes on their properties for orthopaedic applications. The materials and processes included two molecular weight materials (GUR 1020 and GUR 1050), two fabricated forms (ram extruded bar and compression-molded sheet), two irradiation sources (gamma and e-beam) and multiple irradiation doses ranging from 30–120 kGy. Increasing irradiation dose led to increased crosslinking, decreased wear, and decreased toughness. The molecular weight of the starting material and the irradiation source both had effects on the final properties while the fabricated form did not. Wear testing of selected groups indicated that there was a direct correlation with irradiation dose but not with the crosslink density (as calculated from the swell ratio).
Is There a Need for TEMP Standards? A Perspective from a Biomaterials Manufacturer
Authors: Dornish M , Dessen A
Published: February 2009

More often than not users of biopolymers obtain their starting materials from a chemical supply company. Documentation is often lacking and the user is not aware of the fact that a biopolymer's functionality in an application is inherently linked to its characteristics. As a manufacturer of ultrapure biopolymers we have often heard the comment that “your biopolymer didn't work!” More often than not, however, the functional properties of the polymer were not appropriate for the intended use. Variability in naturally occurring biopolymers can lead to failed formulations. Alginate and chitosan are biopolymers that may be used in TEMPs. Derived from natural sources, these materials are particularly complex, and thus exhibit significant variability. Consequently, in order to understand the full range of their properties there is a need for accurate characterization of these materials. The development of standards for such TEMP starting materials is necessary to ensure product uniformity, enable more complete and precise characterization and to inform both users and manufacturers of the relationships among composition, functional properties and utility. This can only lead to more successful TEMP formulations.
Biomolecules in Tissue Engineered Medical Products (TEMPs): A Case Study of Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2)
Authors: Porter TJ , Rathore S , Rouse J , Denton M
Published: February 2009

rhBMP-2 is an osteoinductive protein that, when administered locally, results in the induction of new bone tissue at the site of implantation. The osteoinductive properties of rhBMP-2 first were demonstrated by implantation at ectopic (nonbony) sites in rodents. BMPs are the only protein factors known to induce new, ectopic bone. rhBMP-2/Absorbable Collagen Sponge (ACS) is a TEMP that combines rhBMP-2 with a matrix for implantation. rhBMP-2/ACS is used in long bone fracture repair and spinal fusion. The development of rhBMP-2 protein as the active ingredient in the rhBMP-2/ACS product is summarized. Four aspects of rhBMP-2 development are covered: protein structural characterization, functional characterization, purity analysis and design of comparability studies to support changes in the manufacturing process. Topics discussed include rhBMP-2 as a “biologic” and as a constituent of a combination TEMP. The lessons learned during the development of rhBMP-2/ACS may allow general insight into the development of future standards for TEMPs that contain biologically active proteins.
Auger Electron Spectroscopy in the Scanning Electron Microscope
Authors: Waldrop JR , Marcus HL
Published: February 2009

Recent work devoted to high-spatial resolution (submicron) chemical analysis of solid surfaces by using Auger electron spectroscopy (AES) in a scanning electron microscope (SEM) is reviewed. Particular attention is given to the description of a computerized AES-SEM system and its use. Examples of applications are given, with emphasis on those in the fields of metallurgy and solid-state semiconductor devices.
Residual Stress Measurement and Analysis Using Ultrasonic Techniques
Authors: Noronha PJ , Chapman JR , Wert JJ
Published: February 2009

A technique which utilizes ultrasonic rediation has been developed to measure residual stresses in metals. This technique makes it possible to detect and measure the magnitude of the principle stresses and also to obtain their direction. The velocities of ultrasonic waves in materials are measured as the time to travel a fixed path length, and the change in transit time is related to the applied stress. The linear relationship obtained allows a procedure based on this principle to be used for the measurement of residual stress using surface waves and shear waves. A method for plotting stress profiles through a material using surface waves uses varying frequencies for the ultrasonic wave. A limitation of the shear wave method is considered. The system used for this technique is called the Modified Time of Flight System.
Effect of Specimen Geometry on Hot Torsion Test Results for Solid and Tubular Specimens
Authors: Barraclough DR , Whittaker HJ , Nair KD , Sellars CM
Published: February 2009

Hot torsion tests have been carried out on aluminum, stainless steel, and silicon steel specimens using a wide range of gage length: radius ratios and bore diameters. For stainless steel, which dynamically recrystallises, a higher strain to maximum stress was found for specimens with a gage length : radius ratio <2. Other stress-strain data were unaffected. The use of tubular specimens did not alter deformation curves at low strains but ductility was reduced for large bore sizes, apparently because average rates of crack propagation through the wall were increased.

A new effective radius is proposed for calculation of strains, strain rates, and shear stresses from torque-twist data for solid and tubular specimens.
Some Problems in the Testing of Transformer Oil of Petroleum Origin for Dielectric Breakdown Strength
Authors: Shombert G
Published: February 2009

A description of the process of dielectric breakdown in insulating oils is presented. The technological changes which made necessary the development of ASTM Standard D 1816-67 as an alternative to D 877-67 are described. The emphasis is on practical considerations which influence the variability of the test results and the differing responses of the two methods to these factors. Suggestions are made as to possible modifications in procedure which might reduce the variability of test results without detracting from their practical applicability.
Microchemical Determination of Quartz in Granite Dust Sampled by Size Selective Methods on Membrane Filters
Authors: O'Neill I , Levadie B , Ashe HB
Published: February 2009

This method applies classic microchemical technique, eliminating entirely the transfer of sample materials during analysis. Respirable sized granite dust is analyzed for quartz content colorimetrically. The relative standard error of the determination of quartz in granite, using this method, is 14.7 percent. Erratum to this paper appears in 2(1)
Work of Fracture and Fracture Toughness of Graphite
Authors: Vitovec FH
Published: February 2009

Compact tension tests and notched bend tests, according to Tattersall and Tappin, were performed on nuclear graphite in different orientations relative to the extrusion direction. The extension of slow propagating cracks was measured. The critical crack extension compares with the dimensions of defects in the graphite such as shrinkage cracks, pores and crack-like pores which are caused by the extrusion process. Taking these cracks into account results in comparable fracture toughness values regardless whether they are determined by a load criterion or from the work of fracture.
A Simple Method for Studying Slow Crack Growth
Authors: Williams DP , Evans AG
Published: February 2009

A simple, inexpensive method for studying slow crack growth is described. The method entails measurements of load relaxation at constant displacement using a double torsion specimen. It is demonstrated that the data generated using this technique are in excellent agreement with data obtained using the more complex conventional techniques, for a range of materials—steel, titanium, glass, aluminum oxide, PMMA. These encouraging initial results suggest that additional and more detailed studies using this test procedure are merited.
Acquisition of Computer Aided Design/Analysis Models for Semiconductors
Authors: Case GR
Published: February 2009

Because of the role of the digital computer in the design and analysis of electronic systems, it is becoming increasingly desirable to have suitable computer aided analysis models of semiconductor devices at the time these devices are available for experimental development. This paper describes the development of such computer aided design/analysis (CAD/A) models. The procedures described can be used to develop models based on statistically significant populations of devices. The statistical procedures for selecting devices to be tested, the testing procedures, and the computer codes used for reducing data are described. Examples of computer output and a complete CAD/A model derived using the procedure are included for a sample device.