Minimal Mismatch Research Articles

Auditory Spatial Discrimination and the Mismatch Negativity Response in Hearing-Impaired Individuals.

The aims of the present study were to investigate the ability of hearing-impaired (HI) individuals with different binaural hearing conditions to discriminate spatial auditory-sources at the midline and lateral positions, and to explore the possible central processing mechanisms by measuring the minimal audible angle (MAA) and mismatch negativity (MMN) response. To measure MAA at the left/right 0°, 45° and 90° positions, 12 normal-hearing (NH) participants and 36 patients with sensorineural hearing loss, which included 12 patients with symmetrical hearing loss (SHL) and 24 patients with asymmetrical hearing loss (AHL) [12 with unilateral hearing loss on the left (UHLL) and 12 with unilateral hearing loss on the right (UHLR)] were recruited. In addition, 128-electrode electroencephalography was used to record the MMN response in a separate group of 60 patients (20 UHLL, 20 UHLR and 20 SHL patients) and 20 NH participants. The results showed MAA thresholds of the NH participants to be significantly lower than the HI participants. Also, a significantly smaller MAA threshold was obtained at the midline position than at the lateral position in both NH and SHL groups. However, in the AHL group, MAA threshold for the 90° position on the affected side was significantly smaller than the MMA thresholds obtained at other positions. Significantly reduced amplitudes and prolonged latencies of the MMN were found in the HI groups compared to the NH group. In addition, contralateral activation was found in the UHL group for sounds emanating from the 90° position on the affected side and in the NH group. These findings suggest that the abilities of spatial discrimination at the midline and lateral positions vary significantly in different hearing conditions. A reduced MMN amplitude and prolonged latency together with bilaterally symmetrical cortical activations over the auditory hemispheres indicate possible cortical compensatory changes associated with poor behavioral spatial discrimination in individuals with HI.

Karaciğer sirozu tedavisinde otolog multipotent mezenkimal stromal kök hücresi uygulanması ve sonuçları

Background and Aims:Increase in the number of liver cirrhosis, lack of the sufficient number of donors, high rates of post-operative complications, mortality rates, as well as material and technical shortcomings make search of effective and favorable treatment methods actual. From this point of view, clinical effects of stem cell transplantation captured our attention. The aim of this study is to evaluate the influence of autologous multipotent mesencymal stromal stem cell transplantation on the morphofunctional state of liver during liver cirrhosis. Materials and Methods:For this purpose; experiments were conducted on 49 white male rats (Wistar), 150-180 g weight, minimum of 3 months old. Because they have minimal immunological mismatch in comparison with allogeneic cells, autologous multipotent mesenchymal stromal stem cells were used for the experiments. Liver cirrhosis was modeled in all the experimental animals. To carry out comparative assessment of the effectiveness of the transplantation methods of autologous multipotent mesencymal stromal stem cell, animals were divided into 2 groups. The first group contained 23 rats with autologous multipotent mesencymal stromal stem cell implanted through the portal vein; the second group (24 rats) contained animals with autologous multipotent mesencymal stromal stem cell implanted into the main liver artery. Comparative study of the effectiveness of treatment was carried out based on the morphofunctional state of the liver. Results:The analysis of histomorphologic and biochemical examination results showed higher effectiveness of transarterial transplantation of autologous multipotent mesencymal stromal stem cell into the liver as compared to the intraportal method. It was confirmed by more active regeneration of liver parenchyma, as well as more rapid restoration of functional tests of the liver. Conclusion:Obtained results prove that application of stem cells will be an alternative treatment for organ transplantation in the treatment of liver cirrhosis in the immediate future

Frictional Energy Dissipation in Spherical Contacts Under Presliding: Effect of Elastic Mismatch, Plasticity and Phase Difference in Loading

Behavior of friction at material interfaces is inherently nonlinear causing variations and uncertainties in interfacial energy dissipation. A finite element model (FEM) of an elastic–plastic spherical contact subjected to periodic normal and tangential loads is developed to study fundamental mechanisms contributing to the frictional energy dissipation. Particular attention is devoted to three mechanisms: the elastic mismatch between contacting pairs, plastic deformations, and phase difference between the normal and tangential fluctuations in loading. Small tangential loads simulating mild vibrational environments are applied to the model and resulting friction (hysteresis) loops are used to estimate the energy loss per loading cycle. The energy losses are then correlated against the maximum tangential load as a power-law where the exponents show the degree of nonlinearity. Exponents increase significantly with in-phase loading and increasing plasticity. Although increasing elastic mismatch facilitates more dissipation during normal load fluctuations, it has negligible influence on the power-law exponents in tangential loading. Among all the configurations considered, out-of-phase loading with minimal mismatch and no plasticity lead to the smallest power-law exponents; promising linear frictional dissipation. The duration the contact remains stuck during a loading cycle is found to have a predominant influence on the power-law exponents. Thus, controlling that duration enables tunable degree of nonlinearity and magnitude in frictional energy dissipation.

Smooth Muscle Cell Alignment and Phenotype Control by Melt Spun Polycaprolactone Fibers for Seeding of Tissue Engineered Blood Vessels

A method has been developed to induce and retain a contractile phenotype for vascular smooth muscle cells, as the first step towards the development of a biomimetic blood vessel construct with minimal compliance mismatch. Melt spun PCL fibers were deposited on a mandrel to form aligned fibers of 10 μm in diameter. The fibers were bonded into aligned arrangement through dip coating in chitosan solution. This formed a surface of parallel grooves, 10 μm deep by 10 μm across, presenting a surface layer of chitosan to promote cell surface interactions. The aligned fiber surface was used to culture cells present in the vascular wall, in particular fibroblasts and smooth muscle cells. This topography induced “surface guidance” over the orientation of the cells, which adopted an elongated spindle-like morphology, whereas cells on the unpatterned control surface did not show such orientation, assuming more rhomboid shapes. The preservation of VSMC contractile phenotype on the aligned scaffold was demonstrated by the retention of α-SMA expression after several days of culture. The effect was assessed on a prototype vascular graft prosthesis fabricated from polylactide caprolactone; VSMCs aligned longitudinally along a fiberless tube, whereas, for the aligned fiber coated tubes, the VSMCs aligned in the required circumferential orientation.

Process model-based analysis of highly crystalline and chemically pure molecular beam epitaxy of MgO (111) nano-thin films on 6H-SiC (0001) substrates

A highly two-dimensional and chemically pure MgO (111) thin film grown epitaxially under ultra-high vacuum on a (√3 × √3) R30° reconstructed wideband gap 6H-SiC (0001) substrate surface can serve as a promising minimal mismatch interfacial layer between the substrate surface and a crystalline structure of functional oxide film. However, the reliability and repeatability of the growth process is challenging. In this paper the dynamic termination of the MgO (111) polar oxide during layer-by-layer growth is explained by OH group chemical bonding state of MgO structure. The analysis of causal relationships is conducted at three different thickness levels to account for the sensitivity of film chemistry to the mismatching strain related inherent twist of crystalline structure along the film thickness. The contribution of sources of the undesired bonding states is quantified by examining the process sensitivity trends to the most critical process variable (percentage starting oxygen) at different thickness levels.

Mechanical Stresses Estimation in Silicon and Glass Bonded at Elevated Temperature

During electrostatic bonding, also known as anodic bonding, silicon is bonded to glass by applying an external voltage and simultaneous heating to temperatures of 200...450 $\deg$C. While cooling to working temperature after bonding happened pieces are mutually deformed. Due to linear thermal expansion coefficients mismatch of anodically bonded glass and silicon samples an internal stress state is generated. Such stresses are called thermal mismatch stresses. The aim of this paper is a determination of technological and design solutions to achieve minimal thermal mismatch stresses in resulting bond. The nonlinear dependence of linear thermal expansion coefficients of bonded samples' materials on temperature makes it difficult to minimize thermal mismatch stresses by chosing materials with close average thermal expansion coefficients in particular temperature range. To assess means of lowering thermal mismatch stress in this paper two different ways to describe assembly are used: two thin bonded layers and multilayered composite material. Based on properties of two brands of glass (LK5, Borofloat 33) and silicon used with described mathematical models thermal mismatch stresses at temperature $T_w$ in samples bonded at several different temperatures $T_b$ are evaluated. Bonded silicon surface stress dependence of glass to silicon wafer thickness ratio is evaluated. Based on such evaluations one can say that by varying thickness of glass bonded to silicon one can obtain zero thermal mismatch stress at a particular depth of material or obtain stress of some defined value at this depth. Models of assembly description used in this paper can be used to optimize anodic bonding process parameters. Such usage aimed to minimize thermal mismatch stresses at device working temperatures is presented in this paper.

A need to adopt new strategies for organ donation in Saudi Arabia.

HLA matching in kidney transplantation is a major factor in long-term survival of the graft. In Saudi Arabia, most deceased donors are non-Saudi, making it difficult to achieve minimal HLA mismatches between donor and recipient. To analyze HLA types of 200 deceased donors and compare them with the Saudi population's HLA types. In a retrospective study analyzing HLA types of the last 398 deceased donors processed in a tertiary hospital in Riyadh, Saudi Arabia, HLA types of all donors were compared with HLA types from a control group of healthy Saudi persons. HLA types were significantly different between the deceased donor group and the Saudi population. In all deceased donors, zero mismatches was never achieved. The major differences in HLA types were in HLA-A*02, HLA-B*15, B*40, B*50, HLA-DRB1*14, DRB1*15, and DRB1*04. As most of our deceased donors are non-Saudis, it is difficult to match for HLA-A, HLA-B, and HLA-DR. HLA matching should be attempted nationwide by adopting different strategies, including typing donors centrally and distributing results to all centers, agreeing on a national point system for allocating organs from deceased donors, and making HLA matching a priority, especially for highly sensitized patients.

Exploring demand flexibility in heterogeneous aggregators

With the proposed penetration of electric vehicles and advanced metering technology, the demand side is foreseen to play a major role in flexible energy consumption scheduling. On the other hand, the past several years have witnessed utility companies' growing interests to integrate more renewable energy resources. These renewable resources, for example, wind or solar, due to their intermittent nature, brought great uncertainty to the power grid system. In this article, we propose a mechanism that attempts to mitigate the grid operational uncertainty induced by renewable energies by properly exploiting demand flexibility with the help of advanced smart-metering technology. To address the challenge, we develop a novel locational marginal price (LMP)-based pricing scheme that involves active demand-side participation by casting the network objective as a two-stage Stackelberg game between the local grid operator and several aggregators. In contrast to the conventional notion that generation follows load, our game formulation provides more flexibility for the operators and tries to provide adequate incentives for the loads to follow the (stochastic renewable) generation. We use the solution concept of subgame perfect equilibrium to analyze the resulting game. Subsequently, we discuss the optimal real-time conventional capacity planning for the local grid operator to achieve the minimal mismatch between supply and demand with the wind power integration. Finally, we assess our proposed scheme with field data. The simulation results show that our proposed scheme works reasonably well in the long term, even with simple heuristics.

A Novel Quantitative Image-Based Method for Evaluating Cranial Symmetry and Its Usefulness in Patients Undergoing Surgery for Unicoronal Synostosis

Unicoronal synostosis presents with cranial asymmetry. Fixed points are difficult to identify; surgical results are therefore difficult to evaluate. The aim of this study was to develop a computer-based method for evaluation of forehead symmetry to enable evaluation of surgical results in unicoronal synostosis. The MATLAB tool was programmed to segment computed tomographic images, leaving the outermost contour. Cephalometric images were segmented manually due to lower contrast. A center-point (O) and an end-point were manually defined in the midline of the forehead and at the nonfused coronal suture, respectively. The program then found a point (p) on the fused side, at the same distance from the O as the end-point. The contours of the left and right side of the forehead were thereafter superimposed, and the position of minimal area mismatch of the sides was identified. To correct for growth between preoperative images and follow-up, the number of mismatching pixels was related to the area outlined by the contour of the forehead, the end-point and p. Two quantities, the relative symmetry change and the absolute symmetry change, were defined and evaluated by repeated measurements on spherical and elliptical phantoms and 15 patients. Measurements with the MATLAB program were reliable with an SD of 0.26% to 5.39% for the expected range of differences. The SD was lower for measurements on computed tomographic images than for measurements on cephalometric images. The SD was also lower in patients with large surgical improvement than in patients with little improvement. The results support the use of relative symmetry change to evaluate surgical results. Our new computer-based method is capable of measuring forehead symmetry with good precision. This method can be used for systematic evaluation of surgical outcome for unicoronal synostosis and other asymmetric skull deformities.

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HLA matching in kidney transplantation is a major factor in long term survival of the graft. In Saudi Arabia, the majority of deceased donors (DD) are non-Saudi, making it difficult to achieve minimal HLA mismatches between the donor and the recipient. The aim of this study was to analyze HLA types of 200 DD and compare it with that of the Saudi population. This is a retrospective study analyzing HLA types of the last 200 deceased donors processed at King Abdulaziz Medical City, Riyadh. Results of the HLA types of all donors were compared with HLA types form our control panel of healthy Saudi cohort. HLA types were significantly different between the deceased donor group and the Saudi cohort. In all deceased donors, we never achieved a recipient who is 6/6 HLA zero mismatches. The major differences in HLA types were in HLA-A ∗ 02 (14% in DD vs 30% in Saudi controls), B ∗ 15 (16% in DD vs 5% in Saudi controls), B ∗ 40 (9% in DD vs 2% in Saudi controls), B ∗ 50 (4% in DD vs 19% in Saudi controls), DRB1 ∗ 14 (5% in DD vs 1% in Saudi controls), DRB1 ∗ 15 (21% in DD vs 13% in Saudi controls) and in DRB1 ∗ 04 (10% in DD vs 19% in Saudi controls). As most of our DD are non-Saudis this makes it difficult to match for HLA-A, B and DR. HLA-DR matching should be attempted nationwide by adopting different strategies including typing donors centrally and distributing results to all centers, agreeing on a national point system for allocating DD organs.

A first-principle investigation of antigorite up to 30 GPa: Structural behavior under compression

The structure of antigorite ( m = 17) has been studied by density functional theory from 0 to 30 GPa. The fourth-order Birch-Murnaghan equation of state fit of the thermally corrected LDA results yields an equilibrium volume ( V = 2853.13 A3), bulk modulus ( K = 64.6 GPa), and its pressure derivative ( K ′ = 6.94) in good agreement with experimental results. Two changes in compression mechanism occur at 6.1 and 20.5 GPa, individuating three pressure ranges: (1) in the low-pressure range, the antigorite wave flattens and the interlayer thickness decreases rapidly; (2) in the intermediate-pressure range, in-plane rotations of tetrahedra (ditrigonalization) and then wave-bending become the dominant compression mechanisms; (3) in the extreme-pressure range, the mechanism of wave-bending becomes prevalent. The first change reveals the origin of softening found experimentally near 6 GPa: the change in compression mechanism occurs after the minimal mismatch between T- and O-sheets is achieved and is accompanied by an apparent symmetry breaking: accidental degeneracies of structural parameters between short and long halfwaves are lifted, including T-sheet thicknesses and Si-O bond lengths. In the extreme-pressure range, Si-O-Si angles decrease below 122°, which may be the origin of amorphization found experimentally at similar pressure.

Relationship between the tibial anteroposterior axis and the surgical epicondylar axis in varus and valgus knees

Proper rotational alignment in total knee arthroplasty (TKA) is essential for successful outcomes. The surgical epicondylar axis (SEA) has been frequently used to determine the femoral rotational alignment, and the anteroposterior (AP) axis of the tibia described in previous study has been introduced as a line perpendicular to the SEA in healthy knees. However, the rotational relationship between the distal femur and the proximal tibia would vary between normal and osteoarthritic knees, and a question remains whether the rotational relationship between the SEA and the AP axis of the tibia would be the same between normal and osteoarthritic knees. This study aims to determine whether the AP axis of the tibia is actually perpendicular to the SEA and useful for the tibial rotational alignment also in osteoarthritic knees. Preoperative computed tomography scans on 25 varus and 25 valgus knees undergoing TKA were studied. The SEA and the AP axis of the tibia were identified using a three-dimensional software, and the angle between the line perpendicular to the projected SEA and the AP axis was measured. The AP axis of the tibia was 1.7° ± 4.3° and 2.0° ± 4.0° internally rotated relative to the line perpendicular to the SEA in the varus and valgus groups, respectively. The AP axis of the tibia was, on average, perpendicular to the SEA in both varus and valgus knees. The AP axis would be useful for setting the tibial component with minimal rotational mismatch. IV.

Prosthesis–patient mismatch affects long-term survival after mechanical valve replacement

We sought to examine the relationship between the degree of prosthesis-patient mismatch and long-term survival after mechanical aortic valve replacement. Prospectively collected long-term follow-up data from 469 consecutive patients who underwent aortic valve replacement between 1995 and 1998 were reviewed. The indexed effective orifice area was derived from the reference normal values of effective orifice area divided by the patient's body surface area. Outcome was stratified according to the severity of prosthesis-patient mismatch: moderate mismatch was defined as 0.65 to 0.85 cm(2)/m(2) and severe mismatch as less than 0.65 cm(2)/m(2). The Cox proportional-hazards model with propensity score adjustment was used to adjust for the observed differences in baseline characteristics between the mismatch groups. The degree of prosthesis-patient mismatch was minimal in 57% of patients, moderate in 39%, and severe in 4%. Predictors of clinically significant mismatch included small aortic valve sizes (19 and 21 mm), obesity, age greater than 65 years, and class III or IV heart failure. During a median follow-up period of approximately 7.9 years, overall survival was 77% in patients with minimal mismatch, 63% in those with moderate mismatch, and only 47% in those with severe mismatch (P < .001). Moderate or severe mismatch was a significant predictor of poorer survival (hazard ratio, 1.6; 95% confidence interval, 1.4-2.3; P < .01), even after adjustment for all significant clinical predictors (ie, propensity score; hazard ratio, 1.2; 95% confidence interval, 1.0-1.5; P = .05). In a large aortic valve surgery population, prosthesis-patient mismatch occurred in 43% of patients, and those with significant mismatch had worse long-term outcomes than those with minimal mismatch.

Atomic Pillar-Based Nanoprecipitates Strengthen AlMgSi Alloys

Atomic-resolution electron microscopy reveals that pillarlike silicon double columns exist in the hardening nanoprecipitates of AlMgSi alloys, which vary in structure and composition. Upon annealing, the Si2 pillars provide the skeleton for the nanoparticles to evolve in composition, structure, and morphology. We show that they begin as tiny nuclei with a composition close to Mg2Si2Al7 and a minimal mismatch with the aluminum matrix. They subsequently undergo a one-dimensional growth in association with compositional change, becoming elongated particles. During the evolution toward the final Mg5Si6 particles, the compositional change is accompanied by a characteristic structural change. Our study explains the nanoscopic reasons that the alloys make excellent automotive materials.

Radiographic analysis of rotational malalignment between tibial component and femoral component in total knee arthroplasty

To identify possible reasons of rotational mismatch between tibial component and femoral component in total knee arthroplasty and choose a right reference axis for placing the components in the operation and to decrease the complications. Forty normal Chinese knees were studied. There were 20 men and 20 women, and average age was 34 years (range, 18 - 42 years). The images of cross sections of the distal femur were obtained by spiral CT scanning (0.5 mm thickness). Scan direction was aligned to be in the plane perpendicular to the mechanical axis of the tibia. On the images of the distal femur and the proximal tibia, three baselines for the anteroposterior axis of the femoral component were drawn based on the clinical epicondylar axis and the surgical epicondylar axis and 3 degrees lateral rotated to the posterior condylar surfaces of the femur separately, and a baseline for the anteroposterior axis of the tibial component was drawn based on the medial 1/3 of the tibial tuberosity. The rotational mismatch angles were measured between each component by using the Autocad software. The mean rotational mismatch angle between tibial component and femoral component is 2.94 degrees for the clinical epicondylar axis, 6.50 degrees for the surgical epicondylar axis and 6.83 degrees for 3 degrees lateral rotation of the femoral component referenced to the posterior condylar axis separately. Landmarks of each bone were the intrinsic cause of the rotational mismatch in total knee arthroplasty. The clinical epicondylar axis can be chosen for the ideal reference to rotational alignment of the femoral component because of its minimal rotational mismatch between each component.

Robust multi-variable identification: Optimal experimental design with constraints

Model identification for use in the design of multi-variable controllers should utilize an experimental design that optimizes the resulting robust control stability and performance, irrespective of the eventual controller structure or tuning. Previous research has shown that a key factor is to identify a steady-state gain matrix with minimal mismatch in the multi-variable gain directionality. In particular, for ill-conditioned systems, precise estimation of the weak process directions is essential. This research extends prior work to provide two alternative design formulations for robust multi-variable identification that allow seamless inclusion of any linear inequality constraints in the inputs, outputs or combinations thereof. These designs, based on D-optimality theory, produce highly correlated input sequences, and accommodate the input and output constraints by using highly unbalanced replications at the various input condition support-points. The superior effectiveness of the proposed designs over prior methods in the literature is demonstrated on a two-input, two-output binary distillation case study. In addition, the seamless extension of the method to higher-order systems is exhibited via a four-input, four-output fluid catalytic cracking example. Uncertainty in the prior estimate of the steady-state gain matrix and in design implementation is addressed in both of the proposed formulations. Furthermore, the second formulation provides a single tuning parameter to balance the efficacy of robust identification versus minimizing sensitivity to uncertainty. Finally, guidelines are presented for the extension of these methods to non-square systems.

Compact and low‐insertion‐loss dual‐mode patch filter with spur‐lines

AbstractA compact microstrip dual‐mode bandpass filter with inserted spur‐lines at the edge of the patch is proposed. In order to obtain a low insertion loss, the proposed filter has no coupling gaps. Also, it has a size reduction of about 45% at the same resonant frequency as compared conventional dual‐mode bandpass filters. Feed lines with offset are applied to ensure a minimal mismatch. From the measured results, the dual‐mode filter has a 0.58‐dB insertion loss at 1.27 GHz with 12% bandwidth. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 33–34, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20366

On the Clustering of Head-Related Transfer Functions Used for 3-D Sound Localization

Head-related transfer functions (HRTFs) serve the increasingly dominant role of implementation 3-D audio systems, which have been realized in some commercial applications. However, the cost of a 3-D audio system cannot be brought down because the efficiency of computation, the size of memory, and the synthesis of unmeasured HRTFs remain to be made better. This paper presents a way to moderate the memory requirement and computational complexity in order to reduce the cost of a 3-D audio system. We employ the library of HRTF measurements called Knowles Electronics Mannequin for Acoustic Research (KEMAR) as the original data [8]. First of all, each HRTF measurement has to be approximated in the minimum phase, and the length of the HRTF is limited by use of a modified Hamming window function, if necessary. Second, we propose an improved LBG-based clustering algorithm to lower the huge number of HRTFs. During the clustering, each HRTF is represented by its power cepstrum. Only portions of the HRTFs are reserved, and the others are neglected on condition that the minimal average mismatch distance between measured and synthesized HRTFs is achieved. Before applying localization of 3-D sounds, both unmeasured and removed HRTFs can be synthesized by linear interpolation and interaural time difference insertion. Experimental results reveal that the average and the maximum mismatch distances deriving from our improved LBG-based clustering method are less than those from the uniform clustering and LBG-based clustering methods [13].

Grouping of residues based on their contact interactions.

Based on the concept of energy landscape a grouping method of residues for reducing the sequence complexity in proteins is presented. For the Miyazawa and Jernigan matrix, rational groupings of 20 kinds of residues with minimal mismatches, under the consideration of local minima and statistics on correlation between the residues, are studied. A hierarchical tree of groupings relating to different numbers of groups N is obtained, and a plateau around N=8-10 is found, which may represent the basic degree of freedom of the sequence complexity in proteins.

Bottom-up inhibition in lexical selection: Phonological mismatch effects in spoken word recognition

Two phoneme monitoring experiments are reported that examine the amount of lexical activation produced by words containing initial, medial, or final mispronunciations. Experiment 1 showed that minimal (one distinctive feature) mismatches in the initial phoneme produced lexical activation relative to a baseline control nonword, but only when the target phoneme was situated at word offset and not word-internally. This finding suggests that considerable bottom-up support is required to override the inhibitory influence of the initial mismatching phonological information. Experiment 2 revealed no lexical activation after a medial mismatch, a finding that is