Switching Rate Research Articles

Benchmarking phasing software with a whole-genome sequenced cattle pedigree

BackgroundAccurate haplotype reconstruction is required in many applications in quantitative and population genomics. Different phasing methods are available but their accuracy must be evaluated for samples with different properties (population structure, marker density, etc.). We herein took advantage of whole-genome sequence data available for a Holstein cattle pedigree containing 264 individuals, including 98 trios, to evaluate several population-based phasing methods. This data represents a typical example of a livestock population, with low effective population size, high levels of relatedness and long-range linkage disequilibrium.ResultsAfter stringent filtering of our sequence data, we evaluated several population-based phasing programs including one or more versions of AlphaPhase, ShapeIT, Beagle, Eagle and FImpute. To that end we used 98 individuals having both parents sequenced for validation. Their haplotypes reconstructed based on Mendelian segregation rules were considered the gold standard to assess the performance of population-based methods in two scenarios. In the first one, only these 98 individuals were phased, while in the second one, all the 264 sequenced individuals were phased simultaneously, ignoring the pedigree relationships. We assessed phasing accuracy based on switch error counts (SEC) and rates (SER), lengths of correctly phased haplotypes and the probability that there is no phasing error between a pair of SNPs as a function of their distance. For most evaluated metrics or scenarios, the best software was either ShapeIT4.1 or Beagle5.2, both methods resulting in particularly high phasing accuracies. For instance, ShapeIT4.1 achieved a median SEC of 50 per individual and a mean haplotype block length of 24.1 Mb (scenario 2). These statistics are remarkable since the methods were evaluated with a map of 8,400,000 SNPs, and this corresponds to only one switch error every 40,000 phased informative markers. When more relatives were included in the data (scenario 2), FImpute3.0 reconstructed extremely long segments without errors.ConclusionsWe report extremely high phasing accuracies in a typical livestock sample. ShapeIT4.1 and Beagle5.2 proved to be the most accurate, particularly for phasing long segments and in the first scenario. Nevertheless, most tools achieved high accuracy at short distances and would be suitable for applications requiring only local haplotypes.

Differences in Administration of Methotrexate and Impact on Outcome in Low-Risk Gestational Trophoblastic Neoplasia.

Simple SummaryLow-risk gestational trophoblastic neoplasia is a rare but highly curable malignancy. The most common first line treatment is methotrexate, which can be administered in different forms. In order to investigate the impact of route of administration on methotrexate resistance, toxicity demanding treatment switch, complete remission and relapse, we performed an observational study including women with low-risk gestational trophoblastic neoplasia in a population-based setting in Sweden and Denmark. We found that oral compared to intra-muscular administration of methotrexate gives a higher rate of drug resistance, but does not affect rates of complete remission, recurrence or overall survival. Intra-muscular treatment was associated with more toxicity leading to switch of treatment. We conclude that, although a larger proportion of women develop drug resistance, oral methotrexate, which is easy to administer and highly tolerable, could be an option for well-informed and motivated women.Methotrexate (MTX) is frequently used as first-line treatment for low-risk gestational trophoblastic neoplasia (GTN). Intravenous and intramuscular (im) routes of administration are the most common methods, although oral administration is used by some Scandinavian centers. The primary aim of this study was to assess the impact of form of administration (im/oral) on resistance to methotrexate (MTX-R) treatment in low-risk GTN. Secondary aims were time to hCG normalization, rates of toxicity-induced treatment switch, and rates of complete remission and recurrence. In total, 170 women treated at Karolinska University Hospital in Sweden and Aarhus University Hospital in Denmark between 1994 and 2018 were included, of whom 107 were given im and 63 oral MTX. MTX-R developed in 35% and 54% in the im and oral groups, respectively (p = 0.01). There was no difference in days to hCG normalization (42 vs. 41 days, p = 0.50) for MTX-sensitive women. Toxicity-induced treatment switch was only seen in the im group. Complete remission was obtained in 99.1% and 100% (p = 0.44), and recurrence rate within one year was 2.8% and 1.6% (p = 0.29). The form of administration of MTX had a significant impact on development of MTX-R and treatment-associated toxicity, but does not affect rates of complete remission, recurrence or survival.

Mechanisms of motor symptom improvement by long-term Tai Chi training in Parkinson\u2019s disease patients

BackgroundTai Chi has been shown to improve motor symptoms in Parkinson’s disease (PD), but its long-term effects and the related mechanisms remain to be elucidated. In this study, we investigated the effects of long-term Tai Chi training on motor symptoms in PD and the underlying mechanisms.MethodsNinety-five early-stage PD patients were enrolled and randomly divided into Tai Chi (n = 32), brisk walking (n = 31) and no-exercise (n = 32) groups. At baseline, 6 months and 12 months during one-year intervention, all participants underwent motor symptom evaluation by Berg balance scale (BBS), Unified PD rating-scale (UPDRS), Timed Up and Go test (TUG) and 3D gait analysis, functional magnetic resonance imaging (fMRI), plasma cytokine and metabolomics analysis, and blood Huntingtin interaction protein 2 (HIP2) mRNA level analysis. Longitudinal self-changes were calculated using repeated measures ANOVA. GEE (generalized estimating equations) was used to assess factors associated with the longitudinal data of rating scales. Switch rates were used for fMRI analysis. False discovery rate correction was used for multiple correction.ResultsParticipants in the Tai Chi group had better performance in BBS, UPDRS, TUG and step width. Besides, Tai Chi was advantageous over brisk walking in improving BBS and step width. The improved BBS was correlated with enhanced visual network function and downregulation of interleukin-1β. The improvements in UPDRS were associated with enhanced default mode network function, decreased L-malic acid and 3-phosphoglyceric acid, and increased adenosine and HIP2 mRNA levels. In addition, arginine biosynthesis, urea cycle, tricarboxylic acid cycle and beta oxidation of very-long-chain fatty acids were also improved by Tai Chi training.ConclusionsLong-term Tai Chi training improves motor function, especially gait and balance, in PD. The underlying mechanisms may include enhanced brain network function, reduced inflammation, improved amino acid metabolism, energy metabolism and neurotransmitter metabolism, and decreased vulnerability to dopaminergic degeneration.Trial registration This study has been registered at Chinese Clinical Trial Registry (Registration number: ChiCTR2000036036; Registration date: August 22, 2020).

Analysis of antiretroviral therapy switch rate and switching pattern for people living with HIV from a national database in Japan

To report the status of switch rates and time-to-switch of antiretroviral therapy (ART) regimens by evaluating anchor drug classes and common switching patterns in Japanese people living with human immunodeficiency virus (HIV, PLWH). This cross-sectional cohort study extracted data of 28,089 PLWH from the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), which contains data representing the entire population of Japan. PLWH with first prescription records of ART administered between January 2011 and March 2019 were identified (n = 16,069). The median time-to-switch and switch rates of anchor drug classes were estimated by Kaplan–Meier analysis. Brookmeyer–Crowley and Greenwood methods were used to estimate 95% confidence intervals for switch rates and median days, respectively. Switch rates were compared between anchor drug classes by year using log-rank tests. A total of 3108 (19.3%) PLWH switched anchor drug classes from first to second regimens. Switch rates increased continuously over 8 years for non-nucleoside reverse transcriptase inhibitors (NNRTIs) (14.9–65.5%) and protease inhibitors (PIs) (13.2–67.7%), with median time-to-switch of 1826 and 1583 days, respectively. Integrase strand transfer inhibitors (INSTIs) maintained a low switch rate (3.0–7.6%), precluding median-days calculation. Overall, the majority of patients treated initially with NNRTIs and PIs switched to INSTIs regardless of switching times (< 1 year: 67.3% and 85.9%, respectively; ≥ 1 year: 95.5% and 93.6%, respectively). The foremost switching strategies for first-to-second ART regimens are from NNRTIs or PIs to INSTIs regimens that maintain low switch rates long term. There was no observable difference in trend between sex, age and status of AIDS disease at first ART regimen. INSTIs HIV agents may be the most durable anchor drug class for PLWH receiving ART.

Rates of, and factors associated with, switching among generic levothyroxine preparations in commercially insured American adults.

Some practice guidelines warn against generic L-thyroxine preparation switching. To examine the rates of generic L-thyroxine preparation switching within one year of initiating L-thyroxine, and to examine factors associated with switching. Retrospective study using national data from a large administrative claims database from January 2008 through November 2018. Medicare or commercially insured adults (≥18 years) who filled a generic L-thyroxine preparation. At least one switch from one generic L-thyroxine preparation to another within 1 year of L-thyroxine initiation defined by prescription fills. From January 2008 to November 2018, we included 483,390 patients who initiated generic L-thyroxine: mean (SD) age was 61.4 years (15.2), 75.2% were female, 72.6% were white. Within 1 year of initiating therapy, 98,013 (20%) switched to another L-thyroxine generic preparation at least once. In a multivariate logistic regression analysis, factors associated with switching included the number of pharmacies visited to fill L-thyroxine (>2 vs 1 adjusted OR [aOR] 7.15, 95% confidence interval [CI] 6.97-7.34), age ≥75 vs. <45 years (aOR 1.29, 95% CI 1.26-1.33), history of thyroid surgery (aOR 1.22, 95% CI 1.13-1.31), and first L-thyroxine fill date in 2018 vs. 2008 (aOR 3.32, 95% CI 3.14-3.51). One in five patients switched among generic L-thyroxine manufacturers within one year of treatment initiation. Generic L-thyroxine switching occurred more often when more pharmacies were used to fill L-thyroxine. Given existing guideline recommendations, additional studies should clarify the impact of generic L-thyroxine switching on thyroid hormone values.

Abstract TMP72: Comparison Of Transradial Artery Versus Transfemoral Artery Access Mechanical Thrombectomy At A Comprehensive Stroke Center

Introduction: The transradial approach (TRA) is being increasingly adopted by neuro-interventionists and has emerged as an alternative to the traditional transfemoral approach (TFA) for mechanical thrombectomy (MT). We aim to compare various time, technical and outcome parameters in patients who undergo MT via TRF vs. TRA approach. Methods: We performed a retrospective chart review of patients who underwent MT at a comprehensive stroke center from 7/2014 to 12/2020. We compared patients who underwent MT via TRA vs. TRF with respect to time from angio suite arrival to puncture, first pass, second pass and recanalization; time from puncture to first pass, second pass and recanalization; time from arrival to the emergency department (ED) to puncture, first pass, second pass and recanalization; the number of passes, rate of switching, achievement of TICI≥2b score, functional independence (3-month mRS≤2), 3-month mortality and neurological improvement (improvement in NIHSS by ≥4 points) on day 1 and 3. A binary logistic regression analysis was performed, controlling for age, sex, NIHSS, type of anesthesia (general vs. moderate), laterality, and location of clot (internal carotid or middle cerebral artery), ASPECTS≥6, presenting mean arterial pressure, blood glucose, Hb A1C, LDL, intravenous alteplase. Results: 217 patients met our inclusion criteria. The mean age was 64.09±14.4 years. 42 (19.35%) patients underwent MT through the TRA approach. There was a significantly higher rate of conversion from TRA approach to TRF approach (11.90% vs.2.28%; OR, 105.59; 95% CI,5.71-1954.67; P 0.002), but no difference in various time, technical and outcome parameters, as shown in the table. Conclusions: Our study demonstrates no significant difference between TRA and TRF approaches with respect to various time, technical and outcome parameters, with a notable exception of a significantly higher rate of conversion from TRA to TRF approach.

Five-year follow-up study of a population-based prospective cohort of men with low-risk prostate cancer: the treatment options in prostate cancer study (TOPCS): study protocol

IntroductionActive surveillance (AS) is recommended for men with low-risk prostate cancer (LRPC) to reduce overtreatment and to maintain patients’ quality of life (QOL). However, whether African American (AA) men can...

Treatment patterns and health care costs among patients with psoriatic arthritis treated with biologic or targeted synthetic disease-modifying antirheumatic drugs.

BACKGROUND: Biologic and targeted synthetic disease-modifying antirheumatic drug (tsDMARD) therapies are used in management of psoriatic arthritis (PsA). Although previous studies have demonstrated that rates of adherence, persistence, discontinuation, and switching, as well as health care costs, are variable among treatments, limited published data exist on more recently approved therapies. OBJECTIVE: To describe adherence, persistence, discontinuation, reinitiation, switching, dosing patterns, and health care costs among PsA patients treated with biologics and tsDMARDs. METHODS: This was a real-world, retrospective administrative claims study. Adult PsA patients with at least 1 claim for an approved PsA biologic (adalimumab, certolizumab, etanercept, golimumab, infliximab, secukinumab, or ustekinumab) or tsDMARD (apremilast or tofacitinib) between January 1, 2015, and June 30, 2019, were selected from the IBM MarketScan administrative claims databases. The first claim for one of the study treatments determined the index date and drug cohort. Patients were required to be continuously enrolled in their health plans for 12 months before and after the index date and to have at least 1 claim with a diagnosis of PsA in the 12 months before or on the index date. Adherence (measured by proportion of days covered [PDC] and medication possession ratio [MPR]), persistence (< 60-day gap in treatment), discontinuation (> 90-day gap), reinitiation of index drug, switching, and dosing patterns for each index drug were assessed during the 12-month follow-up period. Health care costs were reported per patient per month (PPPM) during the 12-month follow-up and assessed after adjusting PsA treatment costs by the Institute for Clinical and Economic Review discount factors to account for discounts and rebates not usually reflected in claims data and by adherence. RESULTS: Overall, 6,674 patients met the selection criteria. The top 3 index drugs were adalimumab (37%), apremilast (26%), and etanercept (18%). Over 12 months of follow-up, 31%-59% of patients remained persistent on the index drug, whereas 35%-56% discontinued, 13%-29% switched to a different biologic or tsDMARD, and 3%-15% reinitiated the index therapy, depending on the index drug. The mean PDC ranged from 0.51 to 0.69 during the 12-month follow-up and 0.80 to 0.93 during the follow-up period before discontinuation. Dose values were largely consistent with prescribing information, with the exception of secukinumab. Index drug costs PPPM ranged from $2,361 (apremilast) to $6,528 for ustekinumab after adjustment for discounts and adherence. CONCLUSIONS: Results from this real-world analysis suggest that there is substantial variability in persistence, discontinuation, adherence, reinitiating, and switching patterns among the different biologic and tsDMARD treatment options for PsA patients. In addition, this study provides real-world cost data for biologics and tsDMARDs among patients with PsA. DISCLOSURES: This study was funded by Eli Lilly Inc., which participated in analysis and interpretation of data, drafting, reviewing, and approving the publication. All authors contributed to the development of the publication and maintained control over the final content. Murage, Malatestinic, Zhu, Atiya, Kern, Stenger, and Sprabery are employees and stockholders of Eli Lilly Inc. Princic and Park are employed by IBM Watson Health, which received funding from Eli Lilly Inc. to conduct this study. Ogdie has received consulting fees from Amgen, AbbVie, Bristol-Myers Squibb, Celgene, Corrona, Janssen, Lilly, Novartis, and Pfizer and has also received grant support from Pfizer, Novartis, and Amgen. Portions of these data have been presented in poster form at the virtual International Society for Pharmacoeconomics and Outcomes Research (ISPOR) 2020 and Congress of Clinical Rheumatology (CCR) West 2020 conferences.

Nanometer-thin L1-MnAl film with B2-CoAl underlayer for high-speed and high-density STT-MRAM: Structure and magnetic properties

The material development of magnetic tunnel junction with a perpendicular easy axis is in great demand to advance spin-transfer torque magnetoresistive random access memory (STT-MRAM) technologies. To realize high-speed and high-density STT-MRAM, a thin-film magnetic material with large perpendicular anisotropy and small spontaneous magnetization has great potential. Here, we develop a thin-film deposition technique for a-few-nanometer-thin L10-MnAl by sputtering and investigate its structure and magnetic properties. Utilization of the B2-CoAl buffer layer allows us to grow L10-MnAl with a large crystalline anisotropy of 8.5 × 105 J/m3, the small spontaneous magnetization of 0.62 T, and the tolerance for 400 °C annealing even at the MnAl thickness of 2 nm. We calculate the device properties based on the obtained material parameters and find that high retention properties, high-speed switching, and low write-error rate can be obtained at the single-digit-nm region, which are not readily achieved by conventional material systems. The results show the potential of L10-MnAl for high-density and high-speed STT-MRAM.

Switch rates vary due to expected payoff but not due to individual risk tendency

When switching between different tasks, the initiation of task switches may depend on task characteristics (difficulty, salient cues, etc.) or reasons within the person performing the task (decisions, behavioral variability, etc.). The reasons for variance in switching strategies, especially in paradigms where participants are free to choose the order of tasks and the amount of switching between tasks, are not well researched. In this study, we follow up the recent discussion that variance in switching strategies might be partly explained by the characteristics of the person fulfilling the task. We examined whether risk tendency and impulsiveness differentiate individuals in their response (i.e., switch rates and time spent on tasks) to different task characteristics on a tracking-while-typing paradigm. In detail, we manipulated two aspects of loss prospect (i.e., “payoff” as the amount of points that could be lost when tracking was unattended for too long, and “cursor speed” determining the likelihood of such a loss occurring). To account for between-subject variance and within-subject variability in the data, we employed linear mixed effect analyses following the model selection procedure (Bates, Kliegl, et al., 2015). Besides, we tested whether risk tendency can be transformed into a decision parameter which could predict switching strategies when being computationally modelled. We transferred decision parameters from the Decision Field Theory to model “switching thresholds” for each individual. Results show that neither risk tendency nor impulsiveness explain between-subject variance in the paradigm, nonetheless linear mixed-effects models confirmed that within-subject variability plays a significant role for interpreting dual-task data. Our computational model yielded a good model fit, suggesting that the use of a decision threshold parameter for switching may serve as an alternative means to classify different strategies in task switching.

Switching Interacting Particle Systems: Scaling Limits, Uphill Diffusion and Boundary Layer

This paper considers three classes of interacting particle systems on {{mathbb {Z}}}: independent random walks, the exclusion process, and the inclusion process. Particles are allowed to switch their jump rate (the rate identifies the type of particle) between 1 (fast particles) and epsilon in [0,1] (slow particles). The switch between the two jump rates happens at rate gamma in (0,infty ). In the exclusion process, the interaction is such that each site can be occupied by at most one particle of each type. In the inclusion process, the interaction takes places between particles of the same type at different sites and between particles of different type at the same site. We derive the macroscopic limit equations for the three systems, obtained after scaling space by N^{-1}, time by N^2, the switching rate by N^{-2}, and letting Nrightarrow infty . The limit equations for the macroscopic densities associated to the fast and slow particles is the well-studied double diffusivity model. This system of reaction-diffusion equations was introduced to model polycrystal diffusion and dislocation pipe diffusion, with the goal to overcome the limitations imposed by Fick’s law. In order to investigate the microscopic out-of-equilibrium properties, we analyse the system on [N]={1,ldots ,N}, adding boundary reservoirs at sites 1 and N of fast and slow particles, respectively. Inside [N] particles move as before, but now particles are injected and absorbed at sites 1 and N with prescribed rates that depend on the particle type. We compute the steady-state density profile and the steady-state current. It turns out that uphill diffusion is possible, i.e., the total flow can be in the direction of increasing total density. This phenomenon, which cannot occur in a single-type particle system, is a violation of Fick’s law made possible by the switching between types. We rescale the microscopic steady-state density profile and steady-state current and obtain the steady-state solution of a boundary-value problem for the double diffusivity model.

Photon-assisted Phase Slips in Superconducting Nanowires

Phase slip is the intrinsic fluctuation of the order parameter and leads to the dissipation of superconductors. Here we propose a photon-assisted phase-slip model in superconducting nanowires to explain the phase-slip rate under photon irradiation. In this phenomenological model, incident photons destroy large quantities of Cooper pairs and reduce the free-energy barrier of phase slips, resulting in proliferation in the phase-slip events and leading to superconducting transition. The switching rates from the superconducting state of a niobium nitride nanowire under various photon irradiation (4.4 mW/m${}^{2}$--4.4 W/m${}^{2}$) and temperatures (2.3--3.7 K) are investigated through the distribution of switching currents in the experiment. The experimental data can be well fitted by our deduced expression of phase-slip rate after eliminating the influence of external noise. Our model develops the phase-slip theory under incident photons and is promising to reveal the intrinsic detection mechanism of the superconducting nanowire single-photon detector.

N01 Type of patient education impacts the willingness to switch from an IV to SC of a biological in patients with Inflammatory Bowel Disease: A multicentre, comparative study

Abstract Background Subcutaneous (SC) formulations of CT-P13 and vedolizumab (VED) are currently available as new treatment option for patients with inflammatory bowel disease (IBD). The decision to switch requires a shared decision making based on adequate education of the patient, to avoid negative outcomes due to a nocebo effect. The aims of this study were (1) to evaluate the percentage of patients with IBD in favour of switching to SC formulations and (2) to compare two educational strategies. Methods This was a multicentre study in patients with IBD on maintenance intravenous (IV) CT-P13 or VED. Patients attending the infusion unit were invited to complete a survey exploring the willingness to switch to SC formulations. In centre A, all patients were informed on the new SC formulations and the accompanying care pathway by an information leaflet and a face-to-face interaction with the IBD nurse, prior to completing the survey. In centre B, patients on a minimal interval of q8w were digital invited to the same survey via the e-health application of the hospital. Demographics, patient reported outcomes, willingness to switch and reasons for IV vs. SC preferences were captured. Results In total, 447 (n=183 Centre A; n=264 Centre B; participation ratio 83.6%) patients completed the survey (m/f: 212/235; CD/UC/IBD-U: 275/161/11; median age 45 IQR 33–57; remission CD/UC: 75%/82%) see table. Most patients were open to SC treatment (47% yes, 33% doubt, 20% no). The main driver to switch was an anticipated decrease in hospital visits (86%) and overall time gain (78%). The main reason to continue IV was fear of change (60%) and uncertainty in case of relapse after switch to a SC formulation (46%). In univariate analysis, the self-estimated compliance rate was associated with the willingness to switch (p&amp;lt;0.0001). To evaluate the impact of the approach in patient education between the two centres, we compared the subgroup of patients on ≥q8w interval with a dosing of 5-10mg/kg CT-P13 or 300 mg VED (n=335). The willingness to switch was higher after a face-to-face approach (centre A) compared to a merely digital approach (centre B; 53.9 % vs. 40.9 % p=0.038), although patients in centre B had a higher educational level (p=0.003), more prior experience with other IBD SC medication (p=&amp;lt;0.001), lived further from the hospital (p&amp;lt;0.001) and had a younger age at diagnosis (p=0.019). Conclusion In this multicentre comparative study exploring the willingness to switch from IV to SC maintenance therapy with CT-P13 and VED, the majority is open to switch to a SC formulation. The direct approach and education of the patient by the IBD nurse impacts significantly the willingness to switch. In a follow-up we will investigate the actual switch rates.

On ergodic control problem for viscous Hamilton–Jacobi equations for weakly coupled elliptic systems

In this article, we study ergodic problems in the whole space RN for weakly coupled systems of viscous Hamilton-Jacobi equations with coercive right-hand sides. The Hamiltonians are assumed to have a fairly general structure, and the switching rates need not be constant. We prove the existence of a critical value ▪ such that the ergodic eigenvalue problem has a solution for every ▪ and no solution for ▪. Moreover, the existence and uniqueness of non-negative solutions corresponding to the value ▪ are also established. We also exhibit the implication of these results to the ergodic optimal control problems of controlled switching diffusions.

Direct Evaluation of Rare Events in Active Matter from Variational Path Sampling.

Active matter represents a broad class of systems that evolve far from equilibrium due to the local injection of energy. Like their passive analogs, transformations between distinct metastable states in active matter proceed through rare fluctuations; however, their detailed balance violating dynamics renders these events difficult to study. Here, we present a simulation method for evaluating the rate and mechanism of rare events in generic nonequilibrium systems and apply it to study the conformational changes of a passive solute in an active fluid. The method employs a variational optimization of a control force that renders the rare event a typical one, supplying an exact estimate of its rate as a ratio of path partition functions. Using this method we find that increasing activity in the active bath can enhance the rate of conformational switching of the passive solute in a manner consistent with recent bounds from stochastic thermodynamics.

Functionalized MoS2 Nanoribbons for Intrinsic Cold-Source Transistors: A Computational Study

Power dissipation is a great challenge for continuous size scaling in CMOS technology because of the thermal limitation on the switching rate of conventional transistors. Here, to break the thermal tyranny, we propose a series of intrinsic cold-source field-effect transistors (CS-FETs) with steep slopes based on armchair transition-metal dichalcogenides (TMD) nanoribbons (NRs) (MX2NRs, M = Mo, W; X = S, Se, Te). The edge states of the TMD NRs can filter out the high-energy electrons and break the “Boltzmann tyranny” at room temperature. First-principles calculations unveil the electronic properties of −H, −F, and −H–O terminated MX2NRs with different ribbon widths. Based on quantum transport simulation, −F and −H–O terminated MoS2NRs present FET performance better than that of the −H terminated MoS2NR. A steep subthreshold swing (28 mV/decade) and a large ON/OFF ratio (4 × 105) are obtained for the 12-MoS2NR–F FET with a 5 nm channel length. Moreover, the effects of the ribbon width, channel length, bias voltage, edge roughness, and defects on MoS2NR–F FET performance are also investigated. This work demonstrates edge functionalization as an effective approach to modulate the TMD NRs and guides the design of intrinsic cold-source transistors.

Effect of switching time scale of receptor activity on chemotactic performance of Escherichia coli

In the chemotactic motion of Escherichia coli, the switching of transmembrane chemoreceptors between active and inactive states is one of the most important steps of the signaling pathway. We study the effect of this switching time-scale on the chemotactic performance of the cell. We quantify performance by the chemotactic drift velocity of the cell. Our extensive numerical simulations on a detailed theoretical model show that as the activity switching rate increases, the drift velocity increases and then saturates. Our data also show the mean duration of a downhill run decreases strongly with the switching rate, while that of an uphill run decreases relatively slowly. We explain this effect from temporal variation of activity along uphill and downhill trajectories. We show that for large and small switching rates the nature of activity variation show qualitatively different behaviors along a downhill run but similar behavior along an uphill run. This results in a stronger dependence of downhill run duration on the switching rate and relatively milder dependence for uphill run duration.

Flexible and highly dynamic beam shaping for Laser-Based Powder Bed Fusion of metals

In state-of-the-art laser-based powder bed fusion processes, a thin layer of metal powder is typically melted by means of a small, Gaussian-shaped laser spot, limiting the stability and productivity of the process. The application of alternative beam shapes is a current research topic to stabilize, accelerate and extend laser-based powder bed fusion of metals, e.g. by tailoring the microstructure. Static beam shapes and sizes limit the theoretically possible process and geometry freedom. To overcome those limitations, an approach for flexible and highly dynamic beam shaping is presented. The experimental setup is based on two perpendicularly oriented acousto-optic deflectors. A synchronized superposition of the ultrafast deflections (switching rates above 100 kHz) is used to generate sequentially compound quasi-static beam shapes. This quasi-static beam shaping is combined with a state-of-the-art beam deflection system and proved to be a viable solution for improved processing. Specimens with a relative density of more than 99.5 % could be manufactured by applying three selected beam shapes. The proof of concept demonstrates the potential of the setup for flexible, fundamental research on the influence of alternative beam profiles in laser-based powder bed fusion of metals.

On-Line Multistep Predictive Spectral Control of the Distortion in Switched-Mode Converters

In automotive power electronics, distortion and electromagnetic interference (EMI) generated by the switching action of power semiconductors can be a significant challenge for the design of a compact, lightweight vehicle. As semiconductor switching frequencies increase, e.g., through the introduction of new materials, such as gallium nitride and silicon carbide, this problem becomes more severe. We present a control scheme for an automotive dc-to-dc converter that reduces the EMI generated by shaping switching distortion predictively at the run time. The multistep model-predictive control scheme chooses the subsequent switching state that optimizes the output spectrum according to predefined criteria. To achieve real-time operation, it evaluates the possible switching state candidates for the next modulation step without explicitly solving a single Fourier transform. In addition, the switching rate and voltage ripple are controlled in a single unified control law. We present and experimentally validate that the control scheme can indeed run at real time already with currently available mid-range hardware. The results demonstrate that the largest spectral peak of the switching distortion can be decreased by 48 dB compared to conventional pulse-width modulation. Furthermore, spectral gaps can be implemented in the output distortion and altered in real-time, allowing certain frequency bands&#x2014;e.g., bands used by other sensitive electronics such as sensors, communication busses, or tuners&#x2014;to be kept free of EMI from the converter&#x2019;s switching actions.

A Study about the Prevalence of Code Switching in the Junior Secondary Physical Science in the Oshana Education Region

This study was conducted to investigate the prevalence of code switching in the Junior Secondary Physical Science teachers in the Oshana Education Region. The purpose of this study was to find out the extent to which code switching was practised by the Junior Secondary Physical Science teachers in their classrooms. The study sought to answer the following question: What is the prevalence of code switching in the Junior Secondary Physical Science in the Oshana Education Region? The study followed a mixed research design approach (quantitative and qualitative) to collect data from the participants. The population of this study consisted of all the Physical Science teachers for Grades 8 - 10 in the Oshana Education Region and then a sample of 22 teachers was drawn from 10 schools of the population of Grade 8 - 10 Physical Science teachers in Oshana Education Region. In an attempt to get a representative sample of the population, a combination of stratified sampling technique and convenience sampling was used for this study to select the sample. All accessible Junior Secondary Physical Science teachers from the selected schools in the identified strata were conveniently chosen for the study. Triangulation was used by conducting lesson observations, administering questionnaires as well as conducting interviews to collect the data. The findings from the observations, questionnaires and interviews revealed that code switching was prevalent in the Oshana Education Region in Grade 8 - 10 Physical Science classrooms. About 58% of the teachers’ code switched during the lesson observations, 85% admitted that they code switched during the interviews and 77.3% of the participants in questionnaires stated that they code switched in an average Physical Science lesson. It was found from the interviews that 85% of the participants admitted that they code switched in their Physical Science lessons. The study further found that teachers’ code switching was more prevalent in the classrooms where teachers had the same mother tongue as the learners. It can also be concluded from the results of this study that teachers spoke to students mostly in Oshiwambo when they were outside the classroom. The study also found that there were inconsistencies in the findings related to the prevalence of code switching in the Junior Secondary Physical Science classrooms in the Oshana Education Region from all the three research tools. These were evident from the different prevalence rates of code switching that were found by the different data collection instruments employed in this study. The researchers recommend the Ministry of Education to acknowledge that code switching is prevalent in the Junior Secondary Physical Science classrooms. The Ministry needs to formulate a policy that will guide the use of code switching in the Junior Secondary Physical Science classrooms as well as guidelines on how the teachers should handle code switching in the learners’ answers in the national examinations. This study also suggests that there is a need for similar studies to be carried out in the other Education Regions so as to determine the prevalence of code switching at the national level in order to take actions that will benefit all schools in Namibia.