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Providing a subset of previously studied items as retrieval cues can both impair and improve memory for the remaining items. Here, we investigated such part-list cuing effects in younger and older adults’ episodic recall, using listwise directed forgetting to manipulate study context access at test. When context access was maintained, part-list cuing impaired recall regardless of age. In contrast, when context access was impaired, part-list cuing improved recall in younger but not in older adults. The results are consistent with the proposal that older adults show intact inhibition and blocking of competing information, but reduced capability for episodic context reactivation.
In the project, domestic ventilation concepts with PushPull-Fans were investigated. These ventilation units are characterized by a periodically changing supply and exhaust air operation. To ensure balanced operation, these ventilation units are always used in pairs, with one unit being in the exhaust air mode and the other in supply air mode. Measurements were made in a research apartment. The results were used to validate a CFD simulation model for transient studies. A room-by-room layout with two units in one room and a cross-room ventilation layout with two connected units in two rooms were analysed. The age of air was used as the evaluation parameter. With the room-by-room ventilation layout a lower age of air in the bedroom compared to the cross-room layout was obtained. However, in the room-by-room layout, the air flow through the larger living room with connected corridor was poorer in the rear area. With the cross-room layout, the flow through the rooms was more uniform. With the cross-room layout, the average age of air in the apartment could be slightly reduced compared to the room-by-room layout.
In this study, an experimental apparatus is used to excite four U-tube-shaped liquid pistons connected in series, and to study their behaviour. Some of the gas spaces are heated to induce piston oscillations; in others, gas expansion is utilised to produce a refrigeration effect. It was discovered that the liquid piston surface would become unstable and turbulent at relatively low gas charge pressures (2 bar–3 bar). Cylindrical polyethylene floats were employed at each piston surface in order to reduce the area of the free surface of each piston and allow experiments to be conducted over a wide range of operating conditions. Experiments were carried out using gas charge pressures in the range of 1 bar–6 bar. The resulting liquid piston oscillations were measured and analysed to assess the impact of any developing piston instability. Evidence of a liquid piston acceleration limit, likely resulting from the Rayleigh-Taylor instability phenomenon, is consistently observed during the experiments. The use of submerged polyethylene piston floats is found to increase the surface stability and enable maximum accelerations of 25 ms−2 to 30 ms−2.
In March 2019, German-speaking scientists and scholars calling themselves Scientists for Future, published a statement in support of the youth protesters in Germany, Austria, and Switzerland (Fridays for Future, Klimastreik/Climate Strike), verifying the scientific evidence that the youth protestors refer to. In this article, they provide the full text of the statement, including the list of supporting facts (in both English and German) as well as an analysis of the results and impacts of the statement. Furthermore, they reflect on the challenges for scientists and scholars who feel a dual responsibility: on the one hand, to remain independent and politically neutral, and, on the other hand, to inform and warn societies of the dangers that lie ahead.
Wide-bandgap semiconductors such as Silicon Carbide (SiC) or Gallium Nitride (GaN) enable fast switching and high switching frequencies of power electronics. However, this potential can not be exploited due to limitations caused by parasitic elements of packaging and interconnections. This paper shows a possibility to minimize parasitic elements of a half-bridge switching cell with 650 V GaN dies integrated into a printed circuit substrate. A sub-nH commutation loop of 0.5 nH inductance gives superior switching characteristics compared to circuits with packaged dies. Simulation and experimental results of an inverse double pulse test confirm our expectations. This study further reveals additional benefits of the proposed technology in terms of mechanical stability and thermal interfacing to heat sinks compared to circuits with packaged dies.
Power cycling and temperature endurance test of a GaN switching cell with substrate integrated chips
(2019)
We present a reliability study of a half-bridge switching cell with substrate integrated 650 V GaN HEMTs. Power Cycling Testing with a ΔTj of 100 K has revealed thermo-mechanically induced failures of contact vias after more than 220 kcycles. The via failure mode of contact opening is confirmed by reverse-bias pulsed IV-measurements to be primarily triggered by a ΔTj imposed thermal gradient and not by a high Tj. The chip electrical characteristics, however, remained unaffected during Power Cycling. Furthermore, a High Temperature Storage test at 125 °C for 5000 h has shown no changes in the electrical performance of substrate integrated GaN HEMTs.
This paper proposes an ultra-low inductance half-bridge switching cell with substrate integrated 650V GaN bare dies. A vertical parallel-plate waveguide structure with 100 μm layer thickness results in a commutation loop inductance of 0.5 nH resulting in a negligible drain-source voltage overshoot in the inductive load standard pulse test. On the other hand reliable circuit operation requires an assessment of the isolation strength of the thin dielectric layer in the main commutation loop, because critical high local electric fields might occur between the pads. Measurements of the dielectric breakdown voltage followed by a statistical failure analysis provide a characteristic life of 14.7 kV and a 10% quantile of 13.5kV in the Weibull fitted data. This characteristic life depends strongly on the ambient temperature and drops to 4.1kV at 125°C. Additionally, ageing tests show an increasing in dielectric breakdown voltage after 500h, 1000h and 2000h at 125°C high-temperature storage due to resin densification processes.
A discrete-time design method for a robust current controller of a servo drive has been developed. It takes the sampling time, the processing dead time and the dynamic behavior of the A/D converter into account. The theoretical calculations are verified using a test stand for high dynamics. The test stand includes a voice coil motor and power electronics with Gallium Nitride (GaN) power semiconductors for switching frequencies of more than 100 kHz. The bandwidth of the current control loop can be improved from typically 1 kHz to 1.5 kHz with insulated-gate bipolar transistor (IGBT) power semiconductors in state-of-the-art motion control systems to 10 kHz and more.
A calculation method for a robust servo controller design depending on the sampling time and the processing dead time was developed for mechanically stiff drives. With a test stand for high dynamic and high positioning accuracy, the theoretical calculations for the high bandwidth improvements are verified. The test stand includes a voice coil motor and a power electronic with Gallium Nitride (GaN) power semiconductors for switching frequencies of more than 100kHz.
Objective
To validate the International Classification of Functioning, Disability and Health (ICF) Generic-6 in daily routine clinical practice in Mainland China. Specific objectives were to analyze (1) interrater reliability, (2) convergent validity, (3) known group validity, and (4) predictive validity of the ICF Generic-6.
Design
Multicenter prospective cohort study.
Setting
Fifty hospitals from 20 provinces of Mainland China.
Participants
A total of 4510 patients from departments of rehabilitation, orthopedics, neurology, cardiology, pneumology, and cerebral surgery of the participating hospitals with different health conditions were included in this study.
Intervention
Not applicable.
Main Outcome Measures
The assessment was undertaken by nurses with ICF Generic-6 in combination with a numeric rating scale. Interrater reliability was evaluated with intraclass correlation coefficients (ICC). Convergent validity was evaluated with Spearman correlation coefficients between ICF Generic-6 and Medical Outcomes Short Form (SF)-12 items. Known group validity was examined by comparing discharge scores between different discharge destinations. Predictive validity was determined by using ICF Generic-6 baseline scores for estimating length of hospital stay with a loglogistic survival model with gamma shared frailty and cost of in-hospital treatment with a mixed effects generalized linear regression model of the gamma family.
Results
The interrater reliability of items and score of ICF Generic-6 was good with ICCs ranging from 0.67-0.87. ICF Generic-6 items were further correlated with respective SF-12 items. Discharge scores of patients differed significantly by discharge destination. The ICF Generic-6 admission score was a significant predictor of length of stay and treatment cost.
Conclusions
The ICF Generic-6 administered in combination with a 0-10 numeric rating scale is a reliable and valid tool for the collection of minimal information on functioning across various clinical settings.
Background: The International Classification of Functioning, Disability and Health is the international standard for describing and monitoring functioning. While the categories, the units of the classification, were not designed with measurement in mind, the hierarchical structure of the classification lends itself to the possibility of summating categories into some higher order domain. Focusing on the chapters of d4 Mobility, d5 Self-Care and d6 Domestic Life, this study seeks to ascertain if qualifiers rating of categories (0-No problem to 4-Complete problem) within those chapters can be summated, and whether such derived measurement is consistent with estimates obtained from well-known instruments which purport to measure the same constructs.
Methods: The current study applies secondary analysis to data previously collected in the context of validating Core Sets for stroke, rheumatoid arthritis, and osteoarthritis. Data included qualifier-based ratings of the categories in the Core Sets, and the physical functioning sub-scale of the Short-Form 36, and the World Health Organization Disability Assessment Schedule 2.0. To examine qualifier-comparator scale item agreement Kappa statistics were used. To identify whether appropriate gradients of the comparator scales were observed across qualifier levels, an Independent Sample Median Test of the ordinal scores was deployed. To investigate the internal validity of the summated ICF categories, the Rasch model was applied.
Results: Data from 2,927 subjects from Europe, Australasia, Middle East and South America were available for analysis; 36.3% had experienced a stroke, 35.8% osteoarthritis, and 27.9% had rheumatoid arthritis. The items from the Short-Form 36 could not match directly the qualifier categories as the former had only 3 response options. The Kappa between World Health Organization Disability Assessment Schedule 2.0 items and categories was low. For all qualifiers, a significant (<0.001) overall gradient was observed across the comparator scales. Only in few of the World Health Organization Disability Assessment Schedule 2.0 items could no discrete level be detected. The aggregation of the qualifiers at the Chapter and higher order levels mostly revealed fit to the Rasch model. Almost all ICF qualifiers showed ordered thresholds suggesting that the current structure and response options of the qualifiers worked as intended.
Conclusions: The findings of this study provide supporting evidence for the use of the professionally rated categories and associated qualifiers to measure functioning.
Implication for Rehabilitation
- This study provides evidence that functioning data can be collected directly with the International Classification of Functioning, Disability and Health (ICF) by using the ICF categories as items and the ICF qualifiers as rating scale.
- The findings of this study show the aggregated ratings of ICF categories from the chapters d4 Mobility, d5 Self-care, and d6 Domestic life capture a broader spectrum of the construct than the corresponding summated items from the SF36-Physical Function sub-scale and the corresponding items of the World Health Organization Disability Assessment Schedule 2.0.
- This study illustrates the potential of building quantitative measurement by aggregating ICF categories and their qualifier ratings into meaningful domains.
Abstract
Objective: Since the 1990s the Functional Independence Measure (FIM™) was believed to measure 2 different constructs, represented by its motor and cognitive subscales. The practice of reporting FIM™ total scores, together with recent developments in the understanding of the influence of locally dependent items on fit to the Rasch model, raises the question of whether the FIM™ 18-item version can be reported as a unidimensional interval-scaled metric.
Design: Rasch analysis of the FIM™ using testlet approaches to accommodate local response dependency.
Patients: A calibration sample containing 946 cases of data from 11,103 patients undergoing neurological or musculoskeletal rehabilitation in Switzerland in 2016.
Results: Baseline analysis and the traditional testlet approach showed no fit with the Rasch model. When items were grouped into 2 testlets, fit to the Rasch model was achieved, indicating unidimensionality across all 18 items. A transformation table to convert FIM™ raw ordinal scores to the corresponding Rasch interval scaled values was created.
Conclusion: This study provides evidence that FIM™ total scores represent a unidimensional set of items, supporting their use in clinical practice and outcome reporting when applying the respective transformation table. This provides a basis for standardized reporting of functioning.
Lay Abstract
The aim of this study was to look in detail at the FIM™, an assessment tool often used for patients undergoing rehabilitation. Some users report the FIM™ as 2 scores: one related to motor tasks, the other to cognitive tasks; others recommend reporting it as a single score including both motor and cognitive tasks. This study explored whether it is statistically meaningful to sum all the points into a single FIM™ total score. The results support the current practice of summing the points into a single total score for patients undergoing musculo-skeletal and neurological rehabilitation. The results also allowed an interval scale to be derived from the FIM™, enabling a broad range of calculations to be made using the FIM™ score, such as calculating the change in FIM™ outcomes from the time a patient is admitted to a rehabilitation clinic until their discharge.
Background
Limitations in upper limb functioning are common in Musculoskeletal disorders and the Disabilities of the Arm, Shoulder and Hand scale (DASH) has gained widespread use in this context. However, various concerns have been raised about its construct validity and so this study seeks to examine this and other psychometric aspects of both the DASH and QuickDASH from a modern test theory perspective.
Methods
Participants in the study were eligible if they had a confirmed diagnosis of Rheumatoid Arthritis (RA). They were mailed a questionnaire booklet which included the DASH. Construct validity was examined by fit to the Rasch measurement model. The degree of precision of both the DASH and QuickDASH were considered through their Standard Error of Measurement (SEM).
Results
Three hundred and thirty-seven subjects with confirmed RA took part, with a mean age of 62.0 years (SD12.1); 73.6% (n = 252) were female. The median standardized score on the DASH was 33 (IQR 17.5–55.0). Significant misfit of the DASH and QuickDASH was observed but, after accommodating local dependency among items in a two-testlet solution, satisfactory fit was obtained, supporting the unidimensionality of the total sets and the sufficiency of the raw (ordinal or standardized) scores.
Conclusion
Having accommodated local response dependency in the DASH and QuickDASH item sets, their total scores are shown to be valid, given they satisfy the Rasch model assumptions. The Rasch transformation should be used whenever all items are used to calculate a change score, or to apply parametric statistics within an RA population.
Significance and innovations
Most previous modern psychometric analyses of both the DASH and QuickDASH have failed to fully address the effect of a breach of the local independence assumption upon construct validity.
Accommodating this problem by creating ‘super items’ or testlets, removes this effect and shows that both versions of the scale are valid and unidimensional, as applied with a bi-factor equivalent solution to an RA population.
The Standard Error of Measurement of a scale can be biased by failing to take into account the local dependency in the data which inflates reliability and thus making the SEM appear better (i.e. smaller) than the true value without bias.
Background: The Extended Barthel Index (EBI), consisting of the original Barthel Index plus 6 cognitive items, provides a tool to monitor patients’ outcomes in rehabilitation. Whether the EBI provides a unidimensional metric, thus can be reported as a valid sum-score, remains to be examined.
Objective: To examine whether the EBI can be reported as unidimensional interval-scaled metric for neurological and musculoskeletal rehabilitation.
Methods: Rasch analysis of a calibration sample of 800 cases from neurological or musculoskeletal rehabilitation in 2016 in Switzerland.
Results: In the baseline analysis no fit to the Rasch Model was achieved. When accommodating local dependencies with a testlet approach satisfactory fit to the Rasch Model was achieved, and an interval scale transformation table was created.
Conclusion: The results support the reporting of adapted EBI total scores for both rehabilitation groups by applying the interval scaled transformation table presented in this study.
Study design
Mapping of the National Spinal Cord Injury Model System (SCIMS) Database (NSCID) to the International Classification of Functioning, Disability and Health (ICF).
Objectives
To link the content of the latest two versions of the NSCID to the ICF; more specifically (1) to compare the content of the current NSCID 2016–2021 version to its predecessor (NSCID 2011–2016) using the ICF as a neutral reference framework, and (2) to compare the content contained in the NSCID 2016–2021 version with relevant ICF Sets.
Setting
The forms of the NSCID 2016–2021 and 2011–2016 versions were linked to the ICF and contrasted. Comparability of the current version of the NSCID with the ICF Core Set for Spinal Cord Injury (SCI) in the post-acute and long-term context and the two generic ICF sets— ICF Generic-7 and ICF Generic-30 was then examined.
Methods
ICF Linking Rules and descriptive statistics.
Results
The current NSCID 2016–2021 version covers functioning as classified in the ICF with 8 ICF categories more comprehensively than its predecessor does. More than 50% of ICF categories contained in the two ICF Generic Sets were covered. The coverage of the brief ICF Core Sets for SCI by the NSCID 2016–2021 was more than 50%, but the coverage of the comprehensive core sets was low. Results showed the best coverage in the ICF component Activities and Participation.
Conclusions
This study emphasizes how the ICF and its Sets can serve as a reference framework to foster comparability of existing data sets from both clinical practice and research.