Questionnaire experience and the hybrid System Usability Scale: Using a novel concept to evaluate a new instrument

This article presents the concept of questionnaire experience (QX), intending to add a new element to the psychometric evaluation of questionnaires, which may eventually help increase the validity and reliability of instruments. The application of QX is demonstrated in the development of the Hybrid System Usability Scale (H-SUS), making use of items comprising pictorial and verbal elements to measure perceived usability. The H-SUS was modelled on the verbal version of the System Usability Scale (SUS). Since previous research showed advantages of pictorial scales over verbal scales (e.g., higher respondent motivation) but also disadvantages (e.g., longer completion times), we assumed that hybrid scales would combine the advantages of both scale types. The goal of this study was to compare the two instruments by assessing traditional psychometric criteria (convergent, divergent and criterion-related validity, reliability and sensitivity) and respondent-related aspects of QX (respondent workload, respondent motivation, questionnaire preference, and questionnaire completion time). An online experiment was carried out (N = 152), in which participants interacted with a smartphone prototype and subsequently completed the verbal SUS together with the H-SUS. Results indicate good psychometric properties of the H-SUS. Compared to the SUS, the H-SUS showed similar workload levels for questionnaire completion, higher levels of respondent motivation, but longer questionnaire completion time. Overall, the H-SUS is considered a promising alternative for the evaluation of perceived usability. Finally, QX can be considered a useful concept for identifying potential problems of psychometric instruments in a respondent-centred way, which may help improve the quality of future scales

A Rare Case of Radiologically Not Distinguishable Coexistent Meningioma and Vestibular Schwannoma in the Cerebellopontine Angle – Case Report and Literature Review

Background: The simultaneous occurrence of cerebellopontine angle (CPA) meningioma and vestibular schwannoma (VS) in the absence of neurofibromatosis type 2 or history of irradiation is very rare. We report a case with coexistent CPA meningioma and VS, which were radiologically not distinguishable in preoperative imaging. Case Description: A 46-year-old female presented with acute hearing loss, tinnitus and gait ataxia. Otorhinolaryngological diagnostic workup and imaging studies showed an intra- and extrameatal homogenous contrast enhancing lesion. The neuroradiological diagnosis was VS. The patient was operated via the retrosigmoid approach. Intraoperatively two distinct tumors were found: a small, mainly intrameatally located VS and a larger meningioma originating from the dura of the petrous bone. Both tumors were completely microsurgically removed. The patient experienced no new neurological deficit after surgery; particularly facial nerve function was completely preserved. Histopathological examination revealed a fibromatous meningioma and a VS, respectively. Conclusions: The coincidental occurrence of CPA meningioma and VS is very rare. Careful interpretation of imaging studies before surgery is crucial. Even such rare cases should be kept in mind when discussing the therapeutic options with the patient. More studies are needed for a better understanding of mechanisms leading to multiple tumor growth

Self-Report Daily Life Activity as a Prognostic Marker of Idiopathic Pulmonary Fibrosis

BACKGROUND Idiopathic pulmonary fibrosis (IPF) is a progressive disease, leading to substantial physical impairment. The distance walked in 6 min (6MWD) is a measure of exercise tolerance and is of prognostic relevance in IPF. While 6MWD is a punctual measurement which may not be representative, self-reported daily life activity may represent the patients' functional capacity more globally even in less severe affected patients. OBJECTIVES We evaluated and characterized a simple classification system based on the patients' self-reported daily activity and analyzed if this would add significantly to the prognostic information of the 6MWD alone in IPF patients. METHODS Daily life activity was assessed in IPF (n = 156) patients with standardized questions and categorized in activity classes (AC I-IV), comprising the less severe impaired in AC I and II. The 6MWD was also assessed. RESULTS ACs were related to the lung functional impairment and inversely correlated to the 6MWD. Thirty-two patients were in AC I/II, 98 in AC III and 26 patients in AC IV. Thirty-seven (23.7%) patients died during a median follow-up of 14.9 months, comprising 1 patient in AC I/II. In addition, a 6MWD \textless470 m predicted mortality. Combining AC I/II and a 6MWD \textgreater470 m identified a subgroup of patients with favorable outcome. CONCLUSIONS AC is a novel scoring system which can easily be obtained and correlates with lung functional and physical impairments as well as mortality. Moreover, AC adds prognostic information to the 6MWD

Plasma lipid profiles discriminate bacterial from viral infection in febrile children

Fever is the most common reason that children present to Emergency Departments. Clinical signs and symptoms suggestive of bacterial infection are often non-specific, and there is no definitive test for the accurate diagnosis of infection. The 'omics' approaches to identifying biomarkers from the host-response to bacterial infection are promising. In this study, lipidomic analysis was carried out with plasma samples obtained from febrile children with confirmed bacterial infection (n = 20) and confirmed viral infection (n = 20). We show for the first time that bacterial and viral infection produces distinct profile in the host lipidome. Some species of glycerophosphoinositol, sphingomyelin, lysophosphatidylcholine and cholesterol sulfate were higher in the confirmed virus infected group, while some species of fatty acids, glycerophosphocholine, glycerophosphoserine, lactosylceramide and bilirubin were lower in the confirmed virus infected group when compared with confirmed bacterial infected group. A combination of three lipids achieved an area under the receiver operating characteristic (ROC) curve of 0.911 (95% CI 0.81 to 0.98). This pilot study demonstrates the potential of metabolic biomarkers to assist clinicians in distinguishing bacterial from viral infection in febrile children, to facilitate effective clinical management and to the limit inappropriate use of antibiotics

Pictorial System Usability Scale (P-SUS): Developing an Instrument for Measuring Perceived Usability

We have developed a pictorial multi-item scale, called P-SUS (Pictorial System Usability Scale), which aims to measure the perceived usability of mobile devices. The scale is based on the established verbal usability questionnaire SUS (System Usability Scale). A user-centred design process was employed to develop and refine its 10 pictorial items. The scale was tested in a first validation study (N=60) using student participants. Psychometric properties (convergent validity, criterion-related validity, sensitivity, and reliability), as well as the motivation to fill in the scale were assessed. The results indicated satisfactory convergent validity for about two-thirds of the items. Furthermore, strong correlations were obtained for the sum scores between verbal and pictorial SUS, and the pictorial scale was perceived as more motivating than the verbal questionnaire. The P-SUS represents a first attempt to provide a pictorial usability scale for the evaluation of (mobile) devices

Energy rating based on thermal modelling of five different PV technologies

Minute by minute outdoor measurements of five commercial PV modules including multi c-Si, HIT, a-Si/μc-Si, CIS, CdTe over one year were used to develop a model for predicting the individual module temperatures. The simulated module temperatures over a whole year in minute interval correspond to the outdoor measured values within a RMSE of 1.5°C. Input of the model includes irradiance measurements, which are extracted from the measured short circuit current ISC, the measured wind speed and the ambient temperature. The measured energy weighted module temperature for Zurich was found to be between 33.3°C and 38.0°C for the different module types with a maximum difference of 0.8°C relative to the simulated average module temperature. Due to the high module temperature, the annual average efficiency was reduced relative to the STC values by only 2.6% (HIT) and 5.6% (CIS). Another reduction of the STC efficiency could clearly be attributed to the efficiency at low ISC values which classify low irradiance values. The value is a decrease of the annual energy output of 4.7% and an increase of 1.1%. A further loss analysis was performed to separate spectrum related losses resulting in a relative difference of 2% for the tandem compared to the multi c-Si module

Verification of measured PV energy yield versus forecast and loss analysis

Yield forecasting of the commercial design tool PVsyst (v5.6) is compared to the performance measurements of multi crystalline modules in Dietikon, Zurich, during 2011. The total measured horizontal irradiance was 1146 kWh/m2 in 2011. This pyranometer measurement covers 91.5% of the total annual irradiance (determined using IDAWEB data with 100% uptime for Affoltern). The historical irradiance data averaged over decades are about 11.4% (Meteonorm) or 13.6% (PVGIS) lower than the IDAWEB data in 2011. The standard deviation between 2001 and 2011 is about 4.9% with respect to IDAWEB. The measured DC performance ratio (PRDC) is 0.937 with a measurement uncertainty of ±0.031 (k=2). Simulations with manufacturer and optimised parameters showed a deviation to the measurement between 4% and 8%. A second analysis considers shading losses for different shading angles. Calculated losses are about 2% lower than simulated losses with PVsyst using a model of partial shading for a shading angle of 20°. Interesting results could be achieved by determining the loss upon limiting the inverter output power. There is only 4.4% annual loss when the inverter output power is set to a limit of 70 % for the location Dietikon in 2011