Optimal Compromise Research Articles

Development of a prosthesis shoulder mechanism for upper limb amputees: application of an original design methodology to optimize functionality and wearability

The application of a design methodology for the determination of the optimal prosthesis architecture for a given upper limb amputee is presented in this paper along with the discussion of its results. In particular, a novel procedure was used to provide the main guidelines for the design of an actuated shoulder articulation for externally powered prostheses. The topology and the geometry of the new articulation were determined as the optimal compromise between wearability (for the ease of use and the patient's comfort) and functionality of the device (in terms of mobility, velocity, payload, etc.). This choice was based on kinematic and kinetostatic analyses of different upper limb prosthesis models and on purpose-built indices that were set up to evaluate the models from different viewpoints. Only 12 of the 31 simulated prostheses proved a sufficient level of functionality: among these, the optimal solution was an articulation having two actuated revolute joints with orthogonal axes for the elevation of the upper arm in any vertical plane and a frictional joint for the passive adjustment of the humeral intra-extra rotation. A prototype of the mechanism is at the clinical test stage.

Physical Understanding through Variational Reasoning: Electron Sharing and Covalent Bonding

Energy changes of stationary states resulting from geometric parameter changes in the Hamiltonian can be understood by variational reasoning in terms of the physical attributes of the kinetic and the potential energy functionals. In atoms as well as molecules, the energy minimization determines the ground state as the optimal compromise between the potential pull of the nuclear attractions and the localization-resisting kinetic pressure of the electron cloud. This variational competition is analyzed for the exact ab initio ground-state wave function of the hydrogen molecule ion to elucidate the formation of the bond. Its electronic wave function is shown to differ from the ground-state wave function of the hydrogen atom by polarization, sharing, and contraction, and the corresponding contributions to the binding energy are examined in detail. All told, the critical feature is that a molecular orbital, contracting (in the variational context) toward two nuclei simultaneously, can lower its potential energy while maintaining a certain degree of delocalization. As a consequence, its kinetic energy functional has a lower value than that of an orbital contracting toward a single nucleus equally closely. By contrast, the potential energy functional is lowered equally effectively whether the orbital contracts toward one nucleus or simultaneously toward two nuclei. Because of this weaker kinetic energy pressure, the electrostatic potential pull of the nuclei in the molecule is able to attach the orbital more tightly to each of the nuclei than the pull of the single nucleus in the atom is able to do. The role of the virial theorem is clarified. Generalizations to other molecules are discussed.

Optimal Compromise Among Sum and Difference Patterns in Monopulse Antennas: Use of Subarrays and Distributions with Common Aperture Tail

Given a linear antenna array with an excitation distribution affording an optimal sum pattern, subarray weighting allows the same array also to generate a difference pattern, with minimal alteration of the signal feed circuitry. In this approach, it is not necessary to consider the whole array for subarraying: We report that the required feeding networks can be further simplified by keeping the elements at the edges of the array with common excitations for both sum and difference patterns.

Sobolev error estimates and a priori parameter selection for semi-discrete Tikhonov regularization

The goal of this paper is to investigate the Tikhonov–Phillips method for semi-discrete linear ill-posed problems in order to determine tight error bounds and to obtain a good parameter choice. We consider the equation Aƒ = g, where the operator A is known, noisy discrete data with can be observed and a solution ƒ* is sought. Assuming that ƒ* is an element of a Sobolev space, we use the well-known theory of optimal recovery in Hilbert spaces for the reconstruction process. We then provide L2-error estimates in terms of the data density and derive an a priori selection for the regularization parameter, which guarantees an optimal compromise between approximation and stability. Finally, we illustrate the parameter selection with a simple example.

SYNTHESIS OF MONOPULSE SUB-ARRAYED LINEAR AND PLANAR ARRAY ANTENNAS WITH OPTIMIZED SIDELOBES

In this paper, three approaches for the synthesis of the optimal compromise between sum and difference patterns for sub-arrayed linear and planar arrays are presented. The synthesis problem is formulated as the definition of the sub-array configuration and the corresponding sub-array weights to minimize the maximum level of the sidelobes of the compromise difference pattern. In the first approach, the definition of the unknowns is carried out simultaneously according to a global optimization schema. Differently, the other two approaches are based on a hybrid optimization procedures, exploiting the convexity of the problem with respect to the sub-array weights. In the numerical validation, representative results are shown to assess the effectiveness of the proposed approaches. Comparisons with previously published results are reported and discussed, as well. “(c) The Electromagnetics Academy. The final version of this article is available at the url of the journal PIER (Progress In Electromagnetics Research) http://www.jpier.org/PIER/pier.php?paper=09092510

Dispersion of Multi‐walled Carbon Nanotubes in Aqueous Pluronic F127 Solutions for Biological Applications

Because mass‐produced carbon nanotubes (CNTs) are strongly aggregated and highly hydrophobic, processes to make them water soluble are required for biological applications. Suspensions in surfactant solutions are often employed. Among these, Pluronic F127 appear to be highly biocompatible if used at low concentrations. Starting from these results, this work involves a systematic study to clarify the dispersion behaviour of CNTs in Pluronic F127. The results suggest a two‐step process: first, the bundles disaggregate, kinetically driven by the energy supplied to the system; second, they disperse (surfactant adsorption), thermodynamically driven by the surfactant concentration. The dispersion reaction data are well fitted by a first‐order kinetics reaction. By performing a pretreatment step, consisting of stirring at 70°C, the achieved concentration of CNTs in solution is twice that of the traditional process. The proposed procedure provides an optimal compromise between a low Pluronic concentration and a high CNT concentration.

Cycle energy control of magnetorheological dampers on cables

The dissipated cycle energy of magnetorheological (MR) dampers operated at constantcurrent results from controllable hysteretic damping and from almost currentindependent, small viscous damping. Thus, the emulation of Coulomb friction andlinear viscous damping necessitates current modulation during one vibration cycleand therefore current drivers. To avoid this drawback, a cycle energy control(CEC) approach is presented which controls the hysteretic MR damper part suchthat the total MR damper energy equals the energy of optimal linear viscousdamping by constant current during one cycle. The excited higher modes due to thehysteretic damping part are partially damped by the MR damper viscous part.Simulations show that CEC copes better with damper force dynamics and constraintsthan emulated linear viscous damping due to the slow control force dynamicsof CEC which are given by cable amplitude dynamics. It is demonstrated thatCEC of MR dampers with viscosity of approximately 4.65% of the optimal modalviscosity performs better than optimal linear viscous damping. The reason isthat this damper viscosity represents an optimal compromise between maximumenergy spillover to higher modes due to the controllable hysteretic part whichproduces more cable damping and maximum viscous damping of these highermodes. Damping tests on a cable with an MR damper validate the CEC approach.

The Design of a Digital Cerebrovascular Simulation Model for Teaching and Research

We developed a comprehensive cerebral blood flow and intracranial pressure model to simulate and study the complex interactions in cerebrovascular dynamics caused by multiple simultaneous alterations, including normal and abnormal functional states of autoregulation of the brain. Individual published equations (derived from prior animal and human studies) were implemented into a comprehensive simulation program. Included in the normal physiological modeling was cerebral blood flow, arterial blood pressure, and carbon dioxide (CO(2)) partial pressure. We also added external and pathological perturbations, such as head-up position and intracranial hemorrhage. The model performed clinically realistically given inputs of published traumatized patients and cases encountered by clinicians. The pulsatile nature of the output graphics was easy for clinicians to interpret. The maneuvers simulated include changes of basic physiological inputs (e.g., arterial blood pressure, central venous pressure, CO(2) tension, head-up position, and respiratory effects on vascular pressures) as well as pathological inputs (e.g., acute intracranial bleeding, and obstruction of cerebrospinal outflow). Based on the results, we believe the model would be useful to teach complex relationships of brain hemodynamics and study clinical research questions such as the optimal head-up position, the effects of intracranial hemorrhage on cerebral hemodynamics, as well as the best CO(2) concentration, to reach the optimal compromise between intracranial pressure and perfusion. With the ability to vary the model's complexity, we believe it would be useful for both beginners and advanced learners. The model could also be used by practicing clinicians to model individual patients (entering the effects of needed clinical manipulations and then running the model to test for optimal combinations of therapeutic maneuvers).

Effects of Annealing Conditions on Catalytic Activities of Pt-Cu Nanoparticle Electrocatalysts for PEM Fuel Cells

Dealloyed Pt25Cu75 bimetallic nanoparticle electrocatalysts exhibit up to 6 times higher oxygen reduction reaction activities than Pt-C catalysts. The effects of annealing temperature and duration on the catalyst activity are studied, with annealing temperature varied from 600 {degree sign}C to 950 {degree sign}C and for 7h and 14 h. XRD and electrochemical analyses is used to obtain insight to the structural details of the catalyst samples. Information regarding extend of alloying, Pt and Cu compositions and distributions on the nanoparticles and particle (crystallite) sizes is correlated with the trends observed from mass and specific activities of the catalysts. It is found that annealing duration of 14 h offers little or no benefit to catalytic activities compared to 7 h. Pt25Cu75 annealed for 7 h, at 800 {degree sign}C was found as an optimal compromise between the extend of alloying and particle size growth to give the highest catalytic activity.

Enantioselective Organocatalytic Direct Michael Addition of Nitroalkanes to Nitroalkenes Promoted by a Unique Bifunctional DMAP-Thiourea

A new catalyst is designed, synthesized, and evaluated for the asymmetric Michael addition of nitroalkanes to nitroalkenes. The obdurate nature of this reaction has made this a formidable challenge to subdue by asymmetric catalysis. The catalyst design includes a thiourea function to activate the nitroalkene by a double H-bond and a 4-dimethylaminopyridine unit to deprotonate the nitroalkane and to bind the resulting nitronate anion also by a double H-bond. The chiral scaffold for the catalyst is 2,2'-diamino-1,1'-binaphthalene (BINAM), and a bis-conjugate is prepared by the attachment of the thiourea unit and the dimethylaminopyridine moiety (DMAP) via the two amino groups. The resulting catalyst will effect the reaction of nitroalkanes to a variety of nitrostyrenes and gives excellent asymmetric inductions (91-95% ee) over a range of 10 substrates. Remarkably, the asymmetric induction increases with decreasing catalyst loading with the optimal compromise between rate and induction at a loading of 2 mol %.

Residual dipolar coupling measurements of transmembrane proteins using aligned low-q bicelles and high-resolution magic angle spinning NMR spectroscopy.

Bicelles are a major medium form to produce weak alignment of soluble proteins for residual dipolar coupling (RDC) measurements. The obstacle to using the same type of bicelles for transmembrane proteins with solution-state NMR spectroscopy is the loss of signals due to the adhesion or penetration of the proteins into large bicelles, resulting in slow protein tumbling. In this study, weak alignment of the second and third transmembrane domains (TM23) of the human glycine receptor (GlyR) was achieved in low-q bicelles (q = DMPC/DHPC). Although protein-free bicelles with such low q would likely show isotropic properties, the insertion of TM23 induced weakly preferred orientations so that the RDC of the embedded protein can be measured. The extent of the alignment increased but the TM23 signal intensity decreased when q was varied from 0.19 to 0.60. A q of 0.50 was found to be an optimal compromise between alignment and the signal-to-noise ratio. In each pair of NMR experiments for RDC measurements, the same sample and pulse sequence were used, with one being performed at high-resolution magic-angle spinning to obtain pure J-couplings without RDC. A meaningful structure refinement in bicelles was possible by iteratively fitting the experimental RDCs to the back-calculated RDCs using the high-resolution NMR structure of GlyR TM23 in trifluoroethanol as the starting template. Combination of this method with the conventional high-resolution NMR in membrane mimicking mixtures of water and organic solvents offers an attractive way to derive structural information for membrane proteins in their native environment.

TU‐B‐351‐01: Optimizing CT Examination Protocols with Respect to Image Quality and Radiation Dose

CT technology continues to develop at a rapid pace, offering imaging options and features that can dramatically improve image quality. Multichannel systems are now standard and the number of channels and image acquisition options continues to increase, allowing greater coverage per rotation, shorter scan times, and thinner images. Isotropic volumetric data acquisition permits retrospective reconstructions of many different image thicknesses and reformats can be created through multiple planes. These and many other advances have escalated and expanded the utility of CT imaging as a core diagnostic tool.However, coupled with the improved CT technology is the increased complexity of operating the scanners and the elevated potential of increasing the radiation dose. CT operators must choose from multiple options, many of which are interdependent, for the control of the multitude of available features. The impact of each of these options on image quality and radiation dose can range from subtle to substantial, and may not necessarily be obvious to the operator.This lecture will focus on the clinical implications of CT scan parameters and provide guidance on achieving an optimal compromise between image quality and radiation dose when constructing CT scan protocols.Educational Objectives:1. Understand the influence of primary CT scan parameters on image quality and radiation dose.2. Learn how to use imaging task‐specific priorities with consideration for radiation dose when determining scanner settings.

Optimized Shroud Design for Axial Turbine Aerodynamic Performance

This paper presents a comprehensive study of the effect of shroud design in axial turbine aerodynamics. Experimental measurements and numerical simulations have been conducted on three different test cases with identical blade geometry and tip clearances but different shroud designs. The first and second test cases are representative of a full shroud and a nonaxisymmetric partial shroud geometry while the third test case uses an optimized partial shroud. Partial shrouds are sometimes used in industrial application in order to benefit from the advantage of shrouded configuration, as well as reduce mechanical stress on the blades. However, the optimal compromise between mechanical considerations and aerodynamic performances is still an open issue due to the resulting highly three-dimensional unsteady flow field. Aerodynamic performance is measured in a low-speed axial turbine facility and shows that there are clear differences between the test cases. In addition, steady and time resolved measurements are performed together with computational analysis in order to improve the understanding of the effect of the shroud geometry on the flow field and to quantify the sources of the resultant additional losses. The flow field analysis shows that the effect of the shroud geometry is significant from 60% blade height span to the tip. Tip leakage vortex in the first rotor is originated in the partial shroud test cases while the full shroud case presents only a weak indigenous tip passage vortex. This results in a significant difference in the secondary flow development in the following second stator with associated losses that varies by about 1% in this row. The analysis shows that the modified partial shroud design has improved considerably the aerodynamic efficiency by about 0.6% by keeping almost unchanged the overall weight of this component, and thus blade root stresses. The work, therefore, presents a comprehensive flow field analysis and shows the impact of the shroud geometry in the aerodynamic performance.

Biological and Biomechanical Effects of Vancomycin and Meropenem in Acrylic Bone Cement

Antibiotic-loaded bone cement is extensively used in joint arthroplasty, but increasing bacteria resistance against common antibiotics has lead to a demand for alternative drugs. However, bone cement containing new additives must be characterized both biologically and mechanically. This study evaluated elution kinetics, antibacterial activity, and mechanical properties for cement loaded with vancomycin and/or meropenem. The presence of meropenem broadened the antibacterial spectrum and enhanced the elution of vancomycin. The mechanical properties were negatively affected by 1.0 g of vancomycin, but these detrimental effects were acceptable when only 0.5 g of vancomycin were added to a cement containing 0.5 g of meropenem. Further investigations on this formulation with adjusted antibiotic amounts are, however, necessary to reach the optimal compromise between the antibacterial and the mechanical properties of the bone cement.

Examining the sensitivity of MM5–CMAQ predictions to explicit microphysics schemes and horizontal grid resolutions, Part III—The impact of horizontal grid resolution

Examination of model sensitivity to horizontal grid resolutions can help identify optimal compromise in accuracy and computational efficiency for regulatory and research-grade applications of 3-D atmospheric models. In this Part III paper, the performance and sensitivity of simulated precipitation and wet deposition amounts by the MM5/CMAQ model to three horizontal grid resolutions (4-, 12-, and 36-km) are evaluated over North Carolina (NC).In contrast with simulated O3, PM2.5, and some PM2.5 species such as NH4+, simulated precipitation and wet deposition amounts are quite sensitive to grid resolutions. Compared with results at coarser resolutions, simulated precipitation amounts are lower in both August and December at 4-km, with the largest sensitivities to grid resolutions occurring in mountain and coastal regions of NC. For wet deposition predictions, the model performs the best for NO3− at 4-km and for NH4+ and SO42− at 12-km in August, but the best for NH4+ and NO3− at 36-km and for SO42− at 4-km in December. Such sensitivities and lack of clear trends in model performance at various resolutions can be attributed to seasonalities in meteorology and differences in characteristics of land use, emissions and concentrations of PM precursors, as well as nonlinear responses of chemistry and meteorology to grid resolutions. The overall performance trends demonstrate a high sensitivity in precipitation and wet deposition predictions over complex terrain and the fact that higher grid resolution does not always lead to improved model performance.

P.3.17 Do patients benefit from practice? An fMRI study in first episode schizophrenia

Background: Studies attempting to identify predictors of antidepressant response in patients with major depression have reported inconsistent results. One explanation may be the different definitions of outcome used. Methods: 187 depressed subjects were recruited and were randomised to treatment with fluoxetine and nortriptyline. At baseline and 6 weeks, subjects completed Hamilton Depression Rating Scale HDRS-17 and 27, Montgomery Asberg Depression Rating Scale (MADRS), the Hopkins Symptom Checklist (SCL-90) and the Social Adjustment Scale (SAS) as well as the Clinical Global Impression Scale (CGI). Relationships among outcome measures were assessed. Receiver Operator Characteristic (ROC curves) were used to show the diagnostic ability of the MADRS and HDRS in predicting the clinician’s rating. Results: All outcome measures were moderately to highly correlated. All measures were significantly related to the clinician’s global impression, but the strongest associations were with the MADRS score. Using ROC curves we showed that a score of 8 on the HDRS or 14 on the MADRS was the optimal compromise between sensitivity and specificity in dividing this sample into responders and non-responders. A 60% reduction in HDRS and MADRS scores rather than a 50% reduction appeared the most valid division between responders and non-responders. Limitations: We relied on clinician judgement as the validating criterion. The results only apply to a sample of moderately depressed outpatients. Conclusions: The MADRS score seemed to most accurately reflect a clinician’s impression of change. Dividing a sample into responders and non-responders can be approached empirically.

Multi-objective optimization of collaborative manufacturing chain with time-sequence constraints

To realize the sharing and optimization deployment of manufacturing resources, a concept of collaborative manufacturing chain (CMC) is proposed for the manufacturing of complex products in a networked manufacturing environment. To acquire the optimal CMC, a multi-objective optimization model is developed to minimize the comprehensive cost and the whole production load with time-sequence constraints. Non-dominated sorting genetic algorithm (NSGA-II) is applied to solve optimization functions. The optimal solution set of Pareto is obtained. The technique for order preference by similarity to ideal solution (TOPSIS) approach is then used to identify the optimal compromise solution from the optimal solution set of Pareto. Simulation results obtained in this study indicate that the proposed model and algorithm are able to obtain satisfactory solutions.

ChemInform Abstract: Highly Recoverable Pyridinium‐Tagged Hoveyda—Grubbs Pre‐Catalyst for Olefin Metathesis. Design of the Boomerang Ligand Toward the Optimal Compromise Between Activity and Reusability.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Effect of Pulse Duration on Size and Character of the Lesion in Retinal Photocoagulation

To systematically evaluate the effects of laser beam size, power, and pulse duration of 1 to 100 milliseconds on the characteristics of ophthalmoscopically visible retinal coagulation lesions. A 532-nm Nd:YAG laser was used to irradiate 36 retinas in Dutch Belt rabbits with retinal beam sizes of 66, 132, and 330 mum. Lesions were clinically graded 1 minute after placement, their size measured by digital imaging, and their depth assessed histologically at different time points. Retinal lesion size increased linearly with laser power and logarithmically with pulse duration. The width of the therapeutic window, defined by the ratio of the threshold power for producing a rupture to that of a mild coagulation, decreased with decreasing pulse durations. For 132- and 330-mum retinal beam sizes, the therapeutic window declined from 3.9 to 3.0 and 5.4 to 3.7, respectively, as pulse duration decreased from 100 to 20 ms. At pulse durations of 1 millisecond, the therapeutic window decreased to unity, at which point rupture and a mild lesion were equally likely to occur. At shorter pulse durations, the width and axial extent of the retinal lesions are smaller and less dependent on variations in laser power than at longer durations. The width of the therapeutic window, a measure of relative safety, increases with the beam size. Pulse durations of approximately 20 milliseconds represent an optimal compromise between the favorable impact of speed, higher spatial localization, and reduced collateral damage on one hand, and sufficient width of the therapeutic window (> 3) on the other.

TU‐SAMS‐L100J‐03: Optimizing CT Image Protocols With Respect To Quality and Radiation Dose

CT technology continues to develop at a rapid pace, offering imaging options and features that can dramatically improve image quality. Multichannel systems are now commonplace and the number of channels continues to increase, allowing greater coverage per rotation, shorter scan times, and thinner images. Isotropic volumetric data acquisition permits retrospective reconstructions of many different image thicknesses and reformats can be created through multiple planes. These and many other advances have escalated and expanded the utility of CT imaging as a core diagnostic tool.However, coupled with the improved CT technology is the increased complexity of operating the scanners and the elevated potential of increasing the radiation dose. CT operators must choose from multiple options, many of which are interdependent, for the control of the multitude of available features. The impact of each of these options on image quality and radiation dose can range from subtle to substantial, and may not necessarily be obvious to the operator.This lecture will focus on the clinical implications of CT scan parameters and provide guidance on achieving an optimal compromise between image quality and radiation dose when constructing CT scan protocols.Educational Objectives:1. Understand the influence of primary CT scan parameters on image quality and radiation dose.2. Learn how to use imaging task‐specific priorities with consideration for radiation dose when determining scanner settings.