Different Configurations (different + configuration)

Distribution by Scientific Domains
Distribution within Chemistry

Selected Abstracts

Neurostimulation systems for deep brain stimulation: In vitro evaluation of magnetic resonance imaging,related heating at 1.5 tesla

Ali R. Rezai MD
Abstract Purpose To assess magnetic resonance imaging (MRI)-related heating for a neurostimulation system (Activa® Tremor Control System, Medtronic, Minneapolis, MN) used for chronic deep brain stimulation (DBS). Materials and Methods Different configurations were evaluated for bilateral neurostimulators (Soletra® Model 7426), extensions, and leads to assess worst-case and clinically relevant positioning scenarios. In vitro testing was performed using a 1.5-T/64-MHz MR system and a gel-filled phantom designed to approximate the head and upper torso of a human subject. MRI was conducted using the transmit/receive body and transmit/receive head radio frequency (RF) coils. Various levels of RF energy were applied with the transmit/receive body (whole-body averaged specific absorption rate (SAR); range, 0.98,3.90 W/kg) and transmit/receive head (whole-body averaged SAR; range, 0.07,0.24 W/kg) coils. A fluoroptic thermometry system was used to record temperatures at multiple locations before (1 minute) and during (15 minutes) MRI. Results Using the body RF coil, the highest temperature changes ranged from 2.5°,25.3° C. Using the head RF coil, the highest temperature changes ranged from 2.3°,7.1° C.Thus, these findings indicated that substantial heating occurs under certain conditions, while others produce relatively minor, physiologically inconsequential temperature increases. Conclusion The temperature increases were dependent on the type of RF coil, level of SAR used, and how the lead wires were positioned. Notably, the use of clinically relevant positioning techniques for the neurostimulation system and low SARs commonly used for imaging the brain generated little heating. Based on this information, MR safety guidelines are provided. These observations are restricted to the tested neurostimulation system. J. Magn. Reson. Imaging 2002;15:241,250. © 2002 Wiley-Liss, Inc. [source]

SAR and efficiency evaluation of a 900 MHz waveguide chamber for cell exposure

Giuseppe De Prisco
Abstract In this work we present the results of numerical and experimental dosimetry carried out for an in vitro exposure device to irradiate sample groups at 900 MHz. The cells are kept in 8 and 15 ml cell cultures, contained, respectively in T25 and T75 rectangular flasks. The dosimetric assessment of the distribution of the specific absorption rate (SAR) is performed for both the bottom of the flask and the whole volume of the sample to provide results for experiments on either the cell layer or the cell suspension. The irradiating chamber is a rectangular waveguide (WG). Different configurations are considered to assess the optimum orientation and positioning of the cell cultures inside the WG. The system performance is optimal when the electric field is parallel to the sample and the WG is terminated by a matched load. In this condition two 15 or four 8 ml cells cultures can be exposed. The efficiency (ratio between the power absorbed by the sample and the incident power) and the non-uniformity degree (ratio between the standard deviation of SAR values and the average SAR over the sample) are calculated and successfully verified through measurements of the scattering parameters and local temperature increases. In the chosen exposure configuration, the efficiency is 0.40 and the non-uniformity degree is 39% for the 15 ml samples. For the 8 ml samples, the efficiency is 0.19 and a low non-uniformity degree (15%) is found. Bioelectromagnetics 29:429,438, 2008. © 2008 Wiley-Liss, Inc. [source]

Evaluating the impact of a cancer supportive care project in the community: patient and professional configurations of need

Kristian Pollock PhD MA PGCHE
Abstract Advances in cancer care and treatment have created a new and somewhat anomalous category of patients with a diagnosis of non-curative disease who still have a considerable period of life remaining. During much of this time they may remain relatively well, without manifest need for clinical care. The responses of patients to this challenging situation are largely unknown. However, it has been assumed that because they confront a difficult experience they will need, or can benefit from, professional intervention. The implementation of pre-emptive support measures is anticipated to improve patients' resilience in coping with their illness and approaching death. This study aimed to investigate the impact of the keyworker role in a 3-year cancer supportive community care project to identify and provide for the needs of patients with a diagnosis of non-curative cancer. It was a qualitative study incorporating face-to-face interviews and focus groups with 19 healthcare professionals and 25 patients and carers from an urban East Midlands locality and a thematic analysis of qualitative interview and focus group transcripts. The project was positively evaluated by patients, carers and professionals. However, the findings raised questions about the different configuration of ,need' within the lay and professional perspectives and how this should most appropriately be addressed. In contrast to widespread professional assumptions about patients' need for counselling, many patients preferred to turn to their friends and families for support, and to adopt a stance of emotional and personal self-reliance as a strategy for coping with their predicament. The study highlights the continuing orientation of services around professional, rather than patient, agendas and the momentum towards increasing specialisation of professional roles and the medicalisation of everyday life that flows from this. [source]

Cultural Orientation, Ethnic Affiliation, and Negative Daily Occurrences: A Multidimensional Cross-Cultural Analysis

Adital Ben-Ari PhD
The present research focuses on cultural variations in the experience of daily stresses and strains. It simultaneously examines the experiences of daily hassles among people holding different cultural orientations (individualistic vs. collectivist) and different socioethnic groups (Jews and Arabs). Data were gathered from 662 Jewish and 300 Arab Israeli respondents by means of a random telephone number dialing. Differences were found in self-related hassles between individuals holding different cultural orientations and in family-related hassles between members of different ethnic affiliations. Multidimensional scaling analysis revealed a different configuration of relations among hassle domains in four groups of Ethnic Affiliation X Cultural Orientation, yielding a continuum from most typical individualists to most typical collectivists. with groups in cultural transition found in between. [source]

Introducing natural-convective chilling to food engineering undergraduate freshmen: Case studied assisted by CFD simulation and field visualization

J. A. Rabi
Abstract A computational fluid dynamics (CFD)-assisted didactic activity has been applied to Food Engineering freshmen aiming at introducing basic concepts of process modeling and simulation towards the food industry. Evoking natural convection, a relatively simple case study was proposed involving two initially room temperature porous samples (identified as two fruits) that were placed inside a refrigeration chamber. Three different configurations were suggested for placing such warmer samples so that students were asked to order them with respect to their chilling capability, that is, to their ability to chill samples as fast as possible. Freshmen's written answers were collected before CFD was used to simulate and visualize each distinct chilling scenario. Accordingly, a finite-volume FORTRAN simulator for transport phenomena in domains fully or partially filled up with porous matrix was used to help compare each chilling performance. Among all possible combinations, answer distribution is presented and discussed in the light of freshmen's scholar background as well as based on the way natural convection concepts were introduced. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 34,43, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20161 [source]

Technical and economical analysis of 3-LIMB and 4-LIMB three phase transformers in YN/YN network

M. Elleuch
This paper deals with the behaviour of the three phase three limb transformer (with or without tertiary winding) as well as the four limb transformer under unbalanced steady states in a YN/yn network. Technical and economical comparative analysis has been established among the different configurations of the transformers. The opportunity of the replacement of the four limb transformer, currently used in the Tunisian distribution network, by a three limb transformer equipped by a tertiary winding has been discussed. During the analysis, the example of a 20 KVA transformer with a tertiary winding and a fourth limb (which could be removed) has been tested. A satisfactory concurrent is obtained between theoretical and experimental results. [source]

A heterogeneous computing system for data mining workflows in multi-agent environments

EXPERT SYSTEMS, Issue 5 2006
Ping Luo
Abstract: The computing-intensive data mining (DM) process calls for the support of a heterogeneous computing system, which consists of multiple computers with different configurations connected by a high-speed large-area network for increased computational power and resources. The DM process can be described as a multi-phase pipeline process, and in each phase there could be many optional methods. This makes the workflow for DM very complex and it can be modeled only by a directed acyclic graph (DAG). A heterogeneous computing system needs an effective and efficient scheduling framework, which orchestrates all the computing hardware to perform multiple competitive DM workflows. Motivated by the need for a practical solution of the scheduling problem for the DM workflow, this paper proposes a dynamic DAG scheduling algorithm according to the characteristics of an execution time estimation model for DM jobs. Based on an approximate estimation of job execution time, this algorithm first maps DM jobs to machines in a decentralized and diligent (defined in this paper) manner. Then the performance of this initial mapping can be improved through job migrations when necessary. The scheduling heuristic used considers the factors of both the minimal completion time criterion and the critical path in a DAG. We implement this system in an established multi-agent system environment, in which the reuse of existing DM algorithms is achieved by encapsulating them into agents. The system evaluation and its usage in oil well logging analysis are also discussed. [source]

Thermomyces lanuginosus: properties of strains and their hemicellulases

Suren Singh
Abstract The non-cellulolytic Thermomyces lanuginosus is a widespread and frequently isolated thermophilic fungus. Several strains of this fungus have been reported to produce high levels of cellulase-free ,-xylanase both in shake-flask and bioreactor cultivations but intraspecies variability in terms of ,-xylanase production is apparent. Furthermore all strains produce low extracellular levels of other hemicellulases involved in hemicellulose hydrolysis. Crude and purified hemicellulases from this fungus are stable at high temperatures in the range of 50,80°C and over a broad pH range (3,12). Various strains are reported to produce a single xylanase with molecular masses varying between 23 and 29 kDa and pI values between 3.7 and 4.1. The gene encoding the T. lanuginosus xylanase has been cloned and sequenced and is shown to be a member of family 11 glycosyl hydrolases. The crystal structure of the xylanase indicates that the enzyme consists of two ,-sheets and one ,-helix and forms a rigid complex with the three central sugars of xyloheptaose whereas the peripheral sugars might assume different configurations thereby allowing branched xylan chains to be accepted. The presence of an extra disulfide bridge between the ,-strand and the ,-helix, as well as to an increase in the density of charged residues throughout the xylanase might contribute to the thermostability. The ability of T. lanuginosus to produce high levels of cellulase-free thermostable xylanase has made the fungus an attractive source of thermostable xylanase with potential as a bleach-boosting agent in the pulp and paper industry and as an additive in the baking industry. [source]

A Computational Approach on the Osseointegration of Bone Implants Based on a Bio-Active Interface Theory

André Lutz
Abstract In this presentation an integrated approach on the simulation of osseointegration in the boneimplant interface is outlined. Besides the consistent combination of computational bone remodelling simulation and established medical imaging techniques, a new model refinement in terms of a bioactive interface theory is introduced, which enables the simulation of bone ingrowth in rough coated uncemented implants. Under consideration of seven physiological loads of daily motion the bone-implant relative micromotion in a soft tissue region around the endoprosthesis is investigated. As the micromotions are an important factor for osseointegration, because excessive micromotion leads to apposition of fibrous tissue, they are considered for the simulation of osseointegration. Results for different parameter constellations, regarding thickness and stiffness of bone-implant interface layer, are compared and the ingrowth for different configurations is predicted. With these results conclusions can be made about the stability of prosthesis in the host bone, which is an important factor for the clinical success of the treatment (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Joint full-waveform analysis of off-ground zero-offset ground penetrating radar and electromagnetic induction synthetic data for estimating soil electrical properties

D. Moghadas
SUMMARY A joint analysis of full-waveform information content in ground penetrating radar (GPR) and electromagnetic induction (EMI) synthetic data was investigated to reconstruct the electrical properties of multilayered media. The GPR and EMI systems operate in zero-offset, off-ground mode and are designed using vector network analyser technology. The inverse problem is formulated in the least-squares sense. We compared four approaches for GPR and EMI data fusion. The two first techniques consisted of defining a single objective function, applying different weighting methods. As a first approach, we weighted the EMI and GPR data using the inverse of the data variance. The ideal point method was also employed as a second weighting scenario. The third approach is the naive Bayesian method and the fourth technique corresponds to GPR,EMI and EMI,GPR sequential inversions. Synthetic GPR and EMI data were generated for the particular case of a two-layered medium. Analysis of the objective function response surfaces from the two first approaches demonstrated the benefit of combining the two sources of information. However, due to the variations of the GPR and EMI model sensitivities with respect to the medium electrical properties, the formulation of an optimal objective function based on the weighting methods is not straightforward. While the Bayesian method relies on assumptions with respect to the statistical distribution of the parameters, it may constitute a relevant alternative for GPR and EMI data fusion. Sequential inversions of different configurations for a two layered medium show that in the case of high conductivity or permittivity for the first layer, the inversion scheme can not fully retrieve the soil hydrogeophysical parameters. But in the case of low permittivity and conductivity for the first layer, GPR,EMI inversion provides proper estimation of values compared to the EMI,GPR inversion. [source]

International Organizations in Transfer of Infectious Diseases: Iterative Loops of Adoption, Adaptation, and Marketing

GOVERNANCE, Issue 2 2004
Gill Walt
Over the past few years increasing attention has been given to the role of international organizations in the diffusion of policy ideas and promotion of particular macro-level policies. Much of the attention has been on the ideological driving forces behind such policies, and on the extent to which the policies are externally imposed. There has been limited discussion on the bread-and-butter, technical policies of international organizations, and how they devise, adopt, adapt, and then promote what come to be seen as policies of global "best practice." This paper seeks to redress this gap by looking at the process of transfer of two infectious disease policies between international and national levels. It demonstrates that international organizations play different roles in policy transfer at particular stages in the process. The paper suggests that health policy transfer is a long adaptive process, made up of several iterative loops, as research and clinical practices developed in one or more countries are adopted, adapted, and taken up by international organizations which then mobilize support for particular policies, market, and promote them. Assumptions that new ideas about policies flow "rationally" into existing decision making are challenged by the processes analyzed here. Policy transfer, given the experience of these infectious diseases policies, goes through separate, "bottom-up," research-oriented, and "top-down" marketing-oriented loops. Individuals and different configurations of networks play key roles linking these loops. In the process, complex, context-specific policies are repackaged into simplified guidelines for global best practice, leading to considerable contestation within the policy networks. [source]

Private Actors and the State: Internationalization and Changing Patterns of Governance

GOVERNANCE, Issue 1 2002
Christoph Knill
This article investigates the implications of political and economic internationalization on patterns of governance from a statecentric perspective. The actual patterns of governance in internationalized environments can be related to the respective governance capacity of public and private actors, which hinges in turn on the strategic constellation underlying the provision of a public good. The specific strategic constellation varies in three dimensions: the congruence between the scope of the underlying problem and the organizational structures of the related actors, the type of problem, and the institutional context, all of which involve a number of factors. With this concept in mind, we identify four ideal-typed patterns of governance, enabled by different configurations of public and private capacities to formally or factually influence in various ways the social, economic, and political processes by which certain goods are provided. [source]

High-Performance Single Crystal Organic Field-Effect Transistors Based on Two Dithiophene-Tetrathiafulvalene (DT-TTF) Polymorphs

Raphael Pfattner
Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the ,-phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules. [source]

Opportunities for manipulating catchment water balance by changing vegetation type on a topographic sequence: a simulation study

Enli Wang
Abstract This simulation study explores opportunities to reduce catchment deep drainage through better matching land use with soil and topography, including the ,harvesting' (evapotranspiration) of excess water running on to lower land units. A farming system simulator was coupled with a catchment hydrological framework to enable analysis of climate variability and 11 different land-use options as they impact the catchment water balance. These land-use options were arranged in different configurations down a sequence of three hydrologically interconnected slope units (uphill, mid-slope and valley floor land units) in a subcatchment of Simmons Creek, southern New South Wales, Australia. With annual crops, the valley floor land units were predicted to receive 187 mm year,1 of run-on water in addition to annual rainfall in 1 in 10 years, and in excess of 94 mm year,1 in 1 in 4 years. In this valley floor position, predicted drainage averaged approximately 110 mm year,1 under annual crops and pastures, whereas permanent tree cover or perennial lucerne was predicted to reduce drainage by up to 99%. The planting of trees or lucerne on the valley floor units could ,harvest' run-on water, reducing drainage for the whole subcatchment with proportionately small reduction in land areas cropped. Upslope land units, even though often having shallower soil, will not necessarily be the most effective locations to plant perennial vegetation for the purposes of recharge reduction. Water harvesting opportunities are site specific, dependent on the amounts and frequency of flows of water to lower landscape units, the amounts and frequency of deep drainage on the different land units, the relative areas of the different land units, and interactions with land use in the different slope positions. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Analysis of the current methods used to size a wind/hydrogen/fuel cell-integrated system: A new perspective

H. G. Geovanni
Abstract As an alternative to the production and storage of intermittent renewable energy sources, it has been suggested that one can combine several renewable energy technologies in one system, known as integrated or hybrid system, that integrate wind technology with hydrogen production unit and fuel cells. This work assesses the various methods used in sizing such systems. Most of the published papers relate the use of simulation tools such as HOMER, HYBRID2 and TRNSYS, to simulate the operation of different configurations for a given application in order to select the best economic option. But, with these methods one may not accurately determine certain characteristics of the energy resources available on a particular site, the profiles of estimated consumption and the demand for hydrogen, among other factors, which will be the optimal parameters of each subsystem. For example, velocity design, power required for the wind turbine, power required for the fuel cell and electrolyzer and the storage capacity needed for the system. Moreover, usually one makes excessive use of bi-parametric Weibull distribution function to approximate the histogram of the observed wind to the theoretical, which is not appropriate when there are bimodal frequency distributions of wind, as is the case in several places in the world. A new perspective is addressed in this paper, based on general system theory, modeling and simulation with a systematic approach and the use of exergoeconomic analysis. There are some general ideas on the advantages offered in this method, which is meant for the implementation of wind/hydrogen/fuel cell-integrated systems and in-situ clean hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Flows through horizontal channels of porous materials

A.K. Al-Hadhrami
Abstract In this paper, the control volume method (CVM) with the staggered grid system is utilized to solve the two-dimensional Brinkman equation for different configurations of porous media in a horizontal channel. The values of the permeability of sand and clear fluid are considered when performing several numerical investigations which enable the evaluation of the behaviour of the flow through regions that mathematically model some geological features (faults/fractures) present in oil reservoirs or groundwater flows. We have found that the convergence of the CVM can be achieved within a reasonable number of iterations when there is a gap present between a partial barrier of low Darcy number and the channel boundary. However, a complete barrier across the channel results in a very high resistance and hence there is a large pressure drop which causes difficulties in convergence. In order to improve the rate of convergence in such situations, an average pressure correction (APC) technique, which is based on global mass conservation, is developed. The use of this technique, along with the CVM, can rapidly build up the pressure drop across such a barrier and hence dramatically improve the rate of convergence of the iterative scheme. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Method of moments modelling of cylindrical microwave integrated circuits interconnections

M. S. Al Salameh
Abstract In this paper, a numerical technique suitable for characterizing a wide variety of interconnection configurations printed on cylindrical surfaces, is presented. The interconnection lines may have either finite or infinitesimal cross-sections. To model cylindrical interfaces, suitable space-domain integral equations are formulated to represent the potential on conductors and electric field at dielectric interfaces. The solution of the integral equations is then obtained numerically by applying the method of moments (MOM). The objective of this approach is to determine the capacitance matrix of cylindrical interconnection systems with different configurations. From the capacitance matrix, other quantities such as characteristic impedance, coupling coefficient and effective permittivity can be determined. The numerical technique described in this paper is implemented as a general computer program. Various circular cylindrical as well as elliptical cylindrical structures have been solved including microstrip lines and coplanar waveguide lines. The results obtained compare very well with other published data. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Quantification of dynamic mixing performance of single screws of different configurations by visualization and image analysis

A. C.-Y.
Abstract The visualization and image analysis techniques developed by the authors for the study of quantifying the dynamic quality of mixing of a single-screw extruder were employed to investigate the mixing performance of screws of different configurations. The mixing quality was quantified by calculating the variances of the light intensity of the bitmap files cropped from the films taken at the screw length of 15D and 17D of a 45-mm screw diameter single-screw extruder. Temperature and screw speed were the two variables studied. While temperature and back pressure were found to have little effect on the mixing quality, screw speed was demonstrated to be a major factor responsible for the mixing fluctuation observed during extrusion. In fact, screw speed and mixing fluctuation appeared to have a relationship that the higher the screw speed, the bigger the fluctuation (i.e., poorer quality of mixing). The experimental results also revealed that the secondary flight of a barrier screw might be essential to improve the quality of mixing. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:1,15, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20142 [source]

Validation of a New Noninvasive Device for the Monitoring of Peak Endocardial Acceleration in Pigs: Implications for Optimization of Pacing Site and Configuration

Introduction: The peak of endocardial acceleration (PEA) is an index of myocardial contractility. We aimed to (1) demonstrate that the PEA measured by the noninvasive cutaneous precordial application of an accelerometer sensor is related to left ventricular (LV) dP/dt max and (2) assess the usefulness of PEA monitoring during graded ischemia and during different configurations of sequential biventricular pacing. Methods and Results: Measurements of invasive LV dP/dt max were compared with measurements of transcutaneous PEA in seven pigs at baseline and during acute drug infusions; increased heart rate; right, left, biventricular and sequential biventricular pacing before and after graded ischemia induced by the constriction of the left anterior descending coronary artery. A consistent PEA signal was obtained in all animals. PEA changes were highly related to LV dP/dt max changes (r= 0.93; P < 0.001). The changes of LV contractility induced by the different pacing configurations were detected by PEA analysis in the absence of ischemia (r= 0.94; P < 0.001) and in the presence of ischemic LV dysfunction (r= 0.91; P < 0.001). Conclusion: Noninvasive PEA measurement allows monitoring of left ventricular contractility and may be a useful tool to detect global effect of ventricular ischemia and to optimize the choice of both pacing site and pacing configuration. [source]


ABSTRACT The effect of different processing parameters on the degree of mixing and axial and radial pressure drops, during single-phase flow in helical tubes was investigated by using CFD software. Correlations were developed to calculate axial and radial pressure drops, and also the ratio of maximum to average fluid velocities. All of these quantities were found to be dependent on curvature ratio (ratio of tube diameter to coil diameter). Flow visualization experiments were performed to assess the degree of mixing in different configurations. At identical conditions, the degree of mixing was higher in the system with the large curvature ratio, which is in agreement with the simulation results. A minimum ratio of maximum to average fluid velocities of 1.61 was achieved, representing a 20% reduction in hold tube length for Newtonian fluid in laminar flow. [source]

Experimental study of reactive chaotic flows in tubular reactors

AICHE JOURNAL, Issue 8 2005
C. Boesinger
For many reactive processes, fluid mixing has a significant effect on the rate of a chemical reaction and on the quality of the product. Mixing in a chaotic flow reactor is a promising phenomenon to control and optimize chemical processes. The effect of three-dimensional (3-D) chaotic flow advection on mixing efficiency and on chemical reaction advancement is examined. An experimental comparison is made, for low Reynolds number flows, between two tubular reactors made of successive bends, with the same number of bends (equal to 80) mounted in different configurations : a helical configuration (for regular flow) and a chaotic flow configuration with bends in perpendicular planes. We show that the mixing and the chemical reaction (for an instantaneous bimolecular chemical reaction) are more efficient in the chaotic flow reactor than in the helical reactor. The different effects of chaotic advection, molecular diffusion and reaction are discussed in view of laboratory findings. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source]

Pressure generated on a simulated oral analog by impression materials in custom trays of different designs

Radi Masri BDS
Purpose To measure the pressure exerted by maxillary edentulous impressions composed of 3 commonly used impression materials using four different impression tray configurations. Materials and Methods The study was performed using an oral analog that simulated an edentulous maxillary arch. Three pressure transducers were imbedded in the oral analog, 1 in the mid-palate area and the other 2 in the right and left ridge (maxillary first premolar areas). Custom trays of 4 different configurations were fabricated. The 3 impression materials tested were irreversible hydrocolloid, light-body and medium-body vinyl polysiloxane, and polysulfide. A total of 128 impressions were made. The custom tray and the oral analog were mounted using a reline jig. A Satec universal testing machine was used to apply a constant pressure of 2 kg/cm2 over a period of 5 minutes on the loaded custom tray. The pressure was recorded every 10 seconds. Factorial analysis of variance and Tukey's multiple comparison test were used to analyze the results. Results A significant difference in the pressure produced using different impression materials was found (p,0.001). Irreversible hydrocolloid and medium-body vinyl polysiloxane produced a significantly higher pressure than light-body vinyl polysiloxane and polysulfide impression materials. The presence of holes and/or relief did not significantly alter the magnitude of pressure. Conclusions All impression materials produced pressure during maxillary edentulous impression making. Tray modification was not important in changing the amount of pressure produced. The impression materials used had more effect on the pressure produced during impression making on the simulated oral analog. [source]

Perceived Relational Support in Adolescence: Dimensions, Configurations, and Adolescent Adjustment

Ron H. J. Scholte
The perceived relational support from four key providers (father, mother, special sibling, and best friend) on five provisions (quality of information, respect for autonomy, emotional support, convergence of goals, and acceptance) was examined for 2,262 adolescents (aged 12 , 18 years). In a variable-centered approach, factor analyses yielded five dimensions of support: three specific to providers (parent, friend, and sibling support) and two specific to provisions (convergence of goals and respect for autonomy). Only parental support was found to change (decrease) across age. In a person-centered approach, five types of adolescents with different configurations of perceived support were identified. The first three types differed in overall level of support (high, average, and low) for all of the five dimensions; the fourth type represented extremely low support from parents with above-average support from best friends; the fifth type consisted of adolescents with no best friend. These configurations were significantly related to different patterns of adolescent adjustment in various domains (psychological well-being, delinquency, substance use, and peer-group functioning). [source]

Redrawing organ distribution boundaries: Results of a computer-simulated analysis for liver transplantation

Richard B. Freeman MD
For several years, the Organ Procurement and Transplantation Network/United Network for Organ Sharing (UNOS) Liver and Intestinal Transplantation Committee has been examining effects of changes and proposed changes to the liver allocation system. The Institute of Medicine recently recommended that the size of liver distribution units be increased to improve the organ distribution system. Methods to achieve this and the potential impact on patients and transplant centers of such a change are evaluated in this study. In hypothetical scenarios, we combined geographically contiguous organ procurement organizations (OPOs) in seven different configurations to increase the size of liver distribution units to cover populations greater than 9 million persons. Using the UNOS Liver Allocation Model (ULAM), we examined the effect of 17 different organ allocation sequences in these proposed realignments and compared them with those predicted by ULAM for the current liver distribution system by using the following primary outcome variables: number of primary liver transplantations performed, total number of deaths, and total number of life-years saved. Every proposed new liver distribution unit plan resulted in fewer primary transplantations. Many policies increased the total number of deaths and reduced total life-years saved compared with the current system. Most of the proposed plans reduced interregional variation compared with the current plan, but no one plan consistently reduced variation for all outcome variables, and all reductions in variations were relatively small. All new liver distribution unit plans led to significant shifts in the number of transplantations performed in individual OPOs compared with the current system. The ULAM predicts that changing liver distribution units to larger geographic areas has little positive impact on overall results of liver transplantation in the United States compared with the current plan. Enlarging liver distribution units likely will result in significant shifts in organs across current OPO boundaries, which will have a significant impact on the activity of many transplant centers. [source]

Transmission electron microscopy and theoretical analysis of AuCu nanoparticles: Atomic distribution and dynamic behavior

J.A. Ascencio
Abstract Though the application of bimetallic nanoparticles is becoming increasingly important, the local atomistic structure of such alloyed particles, which is critical for tailoring their properties, is not yet very clearly understood. In this work, we present detailed study on the atomistic structure of Au,Cu nanoparticles so as to determine their most stable configurations and the conditions for obtaining clusters of different structural variants. The dynamic behavior of these nanoparticles upon local heating is investigated. AuCu nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and energy filtering elemental composition mapping (EFECM), which allowed us to study the internal structure and the elemental distribution in the particles. Quantum mechanical approaches and classic molecular dynamics methods are applied to model the structure and to determine the lowest energy configurations, the corresponding electronic structures, and understand structural transition of clusters upon heating, supported by experimental evidences. Our theoretical results demonstrate only the core/shell bimetallic structure have negative heat of formation, both for decahedra and octahedral, and energetically favoring core/shell structure is with Au covering the core of Cu, whose reverse core/shell structure is not stable and may transform back at a certain temperature. Experimental evidences corroborate these structures and their structural changes upon heating, demonstrating the possibility to manipulate the structure of such bimetallic nanoparticles using extra stimulating energy, which is in accordance with the calculated coherence energy proportions between the different configurations. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source]

Exploring the possibility of enhancing the bandwidth of ,-negative metamaterials by employing tunable varactors

Andrea Alù
Abstract We analyze here the performance of ,-negative metamaterials in different configurations at microwave and optical frequencies that employ variable values of capacitances or tunable varactors, with the purpose of increasing their bandwidth of operation. The proposed method shows moderately good results both in resonant-like and in transmission-line configurations. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 55,59, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22036 [source]

The role of configuration and coupling in autoregulatory gene circuits

Kang Wu
Summary Autoregulatory gene circuits can be physically encoded within the genome in a number of different configurations. By physical encoding, we mean the orientation and relative proximity of the genes within the circuit. In this work, we quantified the behaviour of an inducible, negatively autoregulated gene circuit arranged in different transcriptional configurations using the tetRA circuit from Tn10 as our basis. Mathematical modelling predicted that circuits arranged in configurations where the expression of the transcription factor is decoupled from its target genes afforded more flexibility relative to configurations where expression is coupled. We found that these decoupled configurations reduced the concentration of transcription factor needed to regulate inducible expression from the circuit. As lower concentrations of transcription factor were required, these decoupled configurations could also be activated at much lower concentrations of the inducer. We experimentally validated these predictions in Escherichia coli by comparing the response of synthetic circuits based on the tetRA circuit arranged in different configurations. Collectively, these results provide one example of how the arrangement of a gene circuit within the genome can affect its behaviour. [source]

Elsewhere and Otherwise: Lévinasian Eros and Ethics in Le Clézio's La quarantaine

Karen D. Levy
Beginning in the 1930s, Emmanuel Lévinas called into question the totalizing priorities of the Western metaphysical tradition and developed a dramatically original description of how subjectivity is constructed in the context of what he terms a face to face encounter with an absolute Other. This destabilizing experience is presented in terms of a summons that demands an ethical response in the form of unqualified moral responsibility for the well being of the Other, without any expectation of reciprocity. In a series of profoundly challenging works, Lévinas analyzes the different stages in the development of this relationship, expressed in masculine oriented terms, and he contrasts the nobility and generosity of ethics with the intimacy of eros and the welcome of the feminine in a protected domestic site. Lévinas insists on the impossibility of fusion and possession in both the ethical and the erotic relationships and seeks to disengage his discourse from essentialist, gender based interpretations. Nevertheless, he privileges terms associated with masculine subjects and likewise seems to endorse stereotypical interpretations of the feminine as fragile and frail, inviting either pity or tenderness. The fact that eros is based on an equivocation between need and the desire for something absolutely Other, which does not depend on any lack, prevents it from attaining the same stature as ethics. And by leaving the feminine out of his discussion of ethics, Lévinas at least downplays the possibility for feminine subjects to respond to the summons of the face to face encounter and accept the risk of living other than in the metaphysical dwelling of Being. The questions raised in Lévinas' works concerning eros, ethics, and the feminine assume different configurations and lead elsewhere when explored in proximity to J.M.G. Le Clézio's emblematic saga La quarantaine. Similar in many ways to Lévinas' philosophical trajectory, Le Clézio's literary undertaking details the disjointed stages of a journey from the self-contained solitude of Being to an exposed elsewhere in what Lévinas calls the "au-delà de l'être." The multi-layered text of La quarantaine fictionalizes the crisis that caused Le Clézio's great-uncle to be erased from family history and depicts the transgenerational effects of that disappearance. The originality of Le Clézio's work stems from the double inscription of the alterity of both eros and ethics in an Other who is gendered female. His text explores the process of rupture and exposure that Lévinas valorizes, but it does so in a way that reveals how a female subject, who both welcomes discreetly and imposes herself indiscreetly, challenges what Lévinas calls the "égoïté tragique" of the other protagonists. Le Clézio's arrestingly beautiful prose serves as a kind of textual face that expresses concretely the complexity of Lévinas' preoccupations and summons us as readers to exceed our capacities and live otherwise. [source]

Political Economy of Economic System Change in the Age of Neoliberalism: A Comparative Study of Germany and Korea

PACIFIC FOCUS, Issue 2 2003
Young-Tae Jung
This paper explores the plausibility of the neoliberal convergence theory, by exploring recent developments in the German and Korean economies. These two countries are the focus of this paper largely because their original economic systems had many features which contrasted with and were distinctive from the Anglo-American economic system; however, it appears that they have now moved toward the Anglo-American system. It will be argued that the neoliberal convergence theory is too simplistic and, therefore, misleading for both theoretical and empirical reasons. Rather, the reality is that different countries and institutions undergo different degrees of change toward the neoliberal model of political economic organization largely due to distinctive characteristics of prior established institutions-more precisely, due to different configurations of socio-political forces. It will be suggested that there may be two alternative development strategies open to the two countries in question for the future. One is that they may have to transform their underlying cultural factors and their ,superstructures'- i.e., political institutions and practices-if an Anglo-American economic system is really recognized as the best for them. The other is that they may have to modify the Anglo-American system to make it more suitable for their societies if the latter is not really the best, but just one of many best, economic systems. [source]

ZnO nanostructures for photovoltaic cells

Belete A. Gonfa
Abstract In this work the use of different ZnO nanostructures has been studied to assess the effect of morphology and surface modification on the performance of photovoltaic devices. ZnO nanostructures (nanoparticles, nanowires and nanofibres) have been produced by different techniques, and surface modified with pyrene-1-carboxylic acid (PCA). The materials prepared were characterized by XRD, UV,Visible spectroscopy, TEM and SEM. The photovoltaic devices have been prepared in two different configurations: glass/ITO/PEDOT:PSS/photoactive layer/Al and glass/ITO/ZnO/photoactive layer/PEDOT:PSS/Ag paste using spin coating and were characterized by current,voltage characteristics measurement under simulated standard illumination conditions. Whilst ZnO nanoparticles yielded the best results, surface modification with PCA resulted in solar cells with higher short circuit current densities but lower open circuit voltage pointing to a better carrier collection but also higher recombination. [source]