Extraction of small-signal model parameters of Si/SiGe heterojunction bipolar transistor using least squares support vector machines

A novel straightforward methodology for extracting bias-dependent small-signal equivalent circuit model parameters (SSECMPs) of silicon/silicon–germanium heterojunction bipolar transistors is presented. The inverse mapping between SSECMPs and scattering (S) parameters is established and fitted using simulated data of the SSECM. Since the problem has large input space, S-parameters at many frequency points, the least squares support vector machines concept is used as regression technique. Physical SSECMPs values are obtained using the proposed methodology. Moreover, an excellent agreement is noted between the S-parameters measurements and their simulated counterpart using the extracted SSECMPs in the frequency range from 40 MHz to 40 GHz at different bias conditions

Cross-Memory Polynomial Modeling for RF Circuits

A new behavioral model is proposed which can provide similar accuracy to the memory polynomial model (MPM) but is shown to have a more efficient architecture for digital hardware implementation. These features have been achieved by the proposed formulation, in which the nonlinear weights of the memory terms are a function of only the present input sample. The new approach is evaluated and compared with the conventional MPM using a Wideband Code Division Multiple Access (WCDMA) signal applied to two different amplifier circuits

Uses and Attitudes of Old and Oldest Adults towards Self-Monitoring Health Systems

Oldest adults (80 years and over) are the fastest growing group in the total world population. This is putting pressure on national healthcare budgets, as the distribution of healthcare expenses is strongly age-dependent. One way of mitigating this burden may be to let older adults contribute to their own health directly by using self-management health systems (SMHS). SMHS might help older, including oldest, adults gain insight into their health status, and invite them to take action. However, while many studies report on user evaluations of older adults with one specific sensor system, fewer studies report on older adults’ uses and attitudes towards integrated SMHS. Moreover, most studies include participants with mean ages of 65 rather than 80. In this paper, we report on a qualitative study, consisting of a focus group interview and a user evaluation of an SMHS by 12 participants with a median age of 85 years. Three main findings were derived: Older adults (1) showed heterogeneity in computer skills, (2) found health technologies useful for others – not yet for themselves, and (3) perceived health technologies as a threat to social interaction. These findings suggest that health technologies are not ready for adoption by older adults yet, and further research on making them more accessible and desirable is required

Is an Impacted Morselized Graft in a Cage an Alternative for Reconstructing Segmental Diaphyseal Defects?

Large diaphyseal bone defects often are reconstructed with large structural allografts but these are prone to major complications. We therefore asked whether impacted morselized bone graft could be an alternative for a massive structural graft in reconstructing large diaphyseal bone defects. Defects in the femora of goats were reconstructed using a cage filled with firmly impacted morselized allograft or with a structural cortical autograft (n = 6 in both groups). All reconstructions were stabilized with an intramedullary nail. The goats were allowed full weightbearing. In all reconstructions, the grafts united radiographically. Mechanical torsion strength of the femur with the cage and structural cortical graft reconstructions were 66.6% and 60.3%, respectively, as compared with the contralateral femurs after 6 months. Histologically, the impacted morselized graft was replaced completely by new viable bone. In the structural graft group, a mixture of new and necrotic bone was present. Incorporation of the impacted graft into new viable bone suggests this type of reconstruction may be safer than reconstruction with a structural graft in which creeping substitution results in a mixture of viable and necrotic bone that can fracture. The data suggest that a cage filled with a loaded morselized graft could be an alternative for the massive cortical graft in reconstruction of large diaphyseal defects in an animal model

Similar revision rate after cemented and cementless femoral revisions for periprosthetic femoral fractures in total hip arthroplasty:analysis of 1,879 revision hip arthroplasties in the Dutch Arthroplasty Register

BACKGROUND AND PURPOSE: Periprosthetic femoral fracture (PPF) after total hip arthroplasty (THA) is a serious complication, as it often is followed by functional deficits and morbidity. There is no consensus regarding the optimal stem fixation method and whether additional cup replacement is beneficial. The aim of our study was to perform a direct comparison of reasons and risk of re-revision between cemented and uncemented revision THAs following PPF using registry data.PATIENTS AND METHODS: 1,879 patients registered in the Dutch Arthroplasty Registry (LROI) who underwent a first-time revision for PPF between 2007 and 2021 (cemented stem: n = 555; uncemented stem: n = 1,324) were included. Competing risk survival analysis and multivariable Cox proportional hazard analyses were performed.RESULTS: 5- and 10-year crude cumulative incidence of re-revision following revision for PPF was similar between cemented (resp. 13%, 95% CI 10-16 and 18%, CI 13-24) and uncemented (resp. 11%, CI 10-13 and 13%, CI 11-16) revisions. Multivariable Cox regression analysis, adjusting for potential confounders, showed a similar risk of revision for uncemented and cemented revision stems. Finally, we found no difference in risk of re-revision between a total revision (HR 1.2, 0.6-2.1) compared with a stem revision.CONCLUSION: We found no difference in the risk of re-revision between cemented and uncemented revision stems after revision for PPF.</p

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty:analysis of 37,976 primary hip arthroplas-ties in the Dutch Arthroplasty Registry

Background and purpose — The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). Patients and methods — In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were mea-sured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the associa-tion between surgical approach and PROMs over time. Results — From baseline to 3 and 12 months, improve-ments for NRS pain scores, EQ-5D, and OHS were com-parable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (–0.2, 95% confidence interval [CI] –2.4 to 1.9) and between DSA and DAA (–1.7, CI –3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved –2.8 points (CI –4.9 to –0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (–1.0, CI –3.2 to 1.1). Conclusion — Our study showed no clinically meaning-ful differences between the DSA and either PLA or DAA.</p

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty:analysis of 37,976 primary hip arthroplas-ties in the Dutch Arthroplasty Registry

Background and purpose — The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). Patients and methods — In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were mea-sured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the associa-tion between surgical approach and PROMs over time. Results — From baseline to 3 and 12 months, improve-ments for NRS pain scores, EQ-5D, and OHS were com-parable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (–0.2, 95% confidence interval [CI] –2.4 to 1.9) and between DSA and DAA (–1.7, CI –3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved –2.8 points (CI –4.9 to –0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (–1.0, CI –3.2 to 1.1). Conclusion — Our study showed no clinically meaning-ful differences between the DSA and either PLA or DAA.</p

Synthetic HNK-1 containing glycans provide insight into binding properties of serum antibodies from MAG-neuropathy patients

Anti-myelin-associated glycoprotein (anti-MAG) neuropathy is an autoimmune disease in which IgM autoantibodies target glycoconjugates of peripheral nerves resulting in progressive demyelination. To examine fine specificities of serum IgM autoantibodies and develop a more robust platform for diagnosis and disease monitoring, we describe here a chemoenzymatic approach that readily provided a panel of HNK-1 containing oligosaccharides presented on type 2 oligo-N-acetyl lactosamine (LacNAc) chains typical of glycosphingolipids. The compounds were prepared by a chemoenzymatic strategy in which an oligo-LacNAc structure was assembled enzymatically and then subjected to protecting group manipulation to chemically install a 3-O-sulfate glucuronic acid moiety. The synthetic strategy is highly divergent and made it possible to prepare from key precursors, additional compounds lacking sulfate of HNK-1 and derivatives in which the HNK-1 epitope is replaced by sulfate or sialic acid. The oligosaccharides were printed as a microarray to examine binding specificities of several monoclonal antibodies and serum antibodies of anti-MAG neuropathy patients. Surprisingly, three distinct patient subgroups were identified with variable dependance on the length of the LacNAc chain and sulfation of the glucuronyl moiety. In most cases, a lacto-neohexaose backbone was required for binding indicating the antibodies target corresponding glycosphingolipids