Suchergebnisse

Abstract
Many academics and researchers have responded to the COVID-19 pandemic by forming on-line national and international collaborative groups to rapidly investigate issues of prevention and treatment. This commentary describes the spontaneous formation of an international team of 115 researchers who summarized the literature on safe methods for decontaminating N95 filtering facepiece respirators in response to the supply crisis. The summary reports and fact sheets on the (www.n95decon.org) website have had more than 200 000 unique visits and the organization's webinars have reached health care professionals from more than 50 countries. The team is extending its mission to cover other personal protective equipment. The success of these collaborations may alter how scientific questions are tackled in the future.

Objective: The author reviews the paper by Kroemer (1972) on the design of the split geometry keyboard and the subsequent 35 years of research on the topic. Background: It was first suggested in the 1920s that arm strain in the typist could be reduced by splitting the keyboard into two halves and inclining the two halves laterally. The first systematic research on the split keyboard was conducted by Kroemer in the 1960s and published in his 1972 article. Methods: The literature on split geometry keyboards was identified, and the progression of the research was reviewed. Results: The Kroemer article marked the beginning of a prolonged, worldwide research effort to determine whether and how the split keyboard design might improve comfort and prevent pain in keyboard users. Conclusions: In the early 1990s, split keyboard designs began to be broadly commercially available. Clear evidence of a health benefit of the split keyboards emerged in the late 1990s. By 2006, a split keyboard was the number one—selling keyboard, of all keyboards sold, in the U.S. retail market. Application: The history of research on this topic, the challenges to changing the conventional design, and the broader acceptance of the split design are a success story with lessons for all of us.

In times of climatic or political grievances that affect not only human life worldwide, but also the environment and the economic situation of a country, a change in the way of thinking about tourism is beginning and the sector of ecotourism is also becoming increasingly important in Germany. The applicability of this form of tourism in the East African destination Kenya in the form of a travel package that is both partly unique and can be designed individually describes the subject matter of this elaboration and is illustrated using the example of the charitable organization Mully Children's Family and the related registered tourism company, MCF Africa Safaris. The underlying research aims to determine how to transform the organisation's own tree planting initiative into a niche tourist market and how this must be geared to gain the interest of the German eco-tourist. Based on the evaluation of the research results, there is high potential, which is dedicated to the implementation of a form of travel consisting of the active support of the named charity and its initiative as well as individually selectable holiday activities in the target market Kenya. As a result, there are basic prerequisites, the consideration of which is essential for the successful integration of the so-called niche market tree planting and the branch-specific nature of ecotourism in the Kenyan travel market.

Abstract
National standards for surgical respirators and masks are written and enforced to protect healthcare workers from particles and microorganisms such as Severe Acute Respriatory Syndrome Coronavirus 2 (SARS-CoV-2). In addition to the ability to filter particles (e.g. filtration efficiency, FE), the standards address breathability (e.g. differential pressure), how well the mask seals to a worker's face (e.g. fit test), the level of protection from a fluid splash, and other factors. Standards used in the USA, European Union (EU), and China were compared with respect to testing methods and certification criteria. Although there are substantial similarities in standards for respirators, such as surgical N95, FFP2, and KN95 filtering facepiece respirators (FFRs), there are differences with respect to who performs that testing and fit-testing requirements that influence certification. There is greater variation in test methods between countries for surgical (USA) or medical (EU and China) masks than for FFRs. Surgical/medical masks can be certified to different levels of protection. The impact of the similarities and differences in testing methods and certification criteria on FFR and mask performance for protecting healthcare workers from SARS-CoV-2 are discussed, as well as the value of a new standard in the EU for testing fabrics for masks used by the public. Health and safety personnel in healthcare settings must understand the differences between standards so that they can select respirators and masks that provide appropriate protection for healthcare workers.

National standards for surgical respirators and masks are written and enforced to protect healthcare workers from particles and microorganisms such as Severe Acute Respriatory Syndrome Coronavirus 2 (SARS-CoV-2). In addition to the ability to filter particles (e.g. filtration efficiency, FE), the standards address breathability (e.g. differential pressure), how well the mask seals to a worker's face (e.g. fit test), the level of protection from a fluid splash, and other factors. Standards used in the USA, European Union (EU), and China were compared with respect to testing methods and certification criteria. Although there are substantial similarities in standards for respirators, such as surgical N95, FFP2, and KN95 filtering facepiece respirators (FFRs), there are differences with respect to who performs that testing and fit-testing requirements that influence certification. There is greater variation in test methods between countries for surgical (USA) or medical (EU and China) masks than for FFRs. Surgical/medical masks can be certified to different levels of protection. The impact of the similarities and differences in testing methods and certification criteria on FFR and mask performance for protecting healthcare workers from SARS-CoV-2 are discussed, as well as the value of a new standard in the EU for testing fabrics for masks used by the public. Health and safety personnel in healthcare settings must understand the differences between standards so that they can select respirators and masks that provide appropriate protection for healthcare workers.

Objective: The purpose of this study was to develop a lexicon for 3-D hand gestures for common human–computer interaction (HCI) tasks by considering usability and effort ratings. Background: Recent technologies create an opportunity for developing a free-form 3-D hand gesture lexicon for HCI. Method: Subjects ( N = 30) with prior experience using 2-D gestures on touch screens performed 3-D gestures of their choice for 34 common HCI tasks and rated their gestures on preference, match, ease, and effort. Videos of the 1,300 generated gestures were analyzed for gesture popularity, order, and response times. Gesture hand postures were rated by the authors on biomechanical risk and fatigue. Results: A final task gesture set is proposed based primarily on subjective ratings and hand posture risk. The different dimensions used for evaluating task gestures were not highly correlated and, therefore, measured different properties of the task–gesture match. Application: A method is proposed for generating a user-developed 3-D gesture lexicon for common HCIs that involves subjective ratings and a posture risk rating for minimizing arm and hand fatigue.

Objective: The objective was to evaluate the effects of vertical key spacing on a conventional computer keyboard on typing speed, percentage error, usability, forearm muscle activity, and wrist posture for both females with small fingers and males with large fingers. Background: Part 1 evaluated primarily horizontal key spacing and found that for male typists with large fingers, productivity and usability were similar for spacings of 17, 18, and 19 mm but were reduced for spacings of 16 mm. Few other key spacing studies are available, and the international standards that specify the spacing between keys on a keyboard have been mainly guided by design convention. Method: Experienced female typists ( n = 26) with small fingers (middle finger length ≤ 7.71 cm or finger breadth of ≤ 1.93 cm) and male typists ( n = 26) with large fingers (middle finger length ≥ 8.37 cm or finger breadth of ≥ 2.24 cm) typed on five keyboards that differed primarily in vertical key spacing (17 × 18, 17 × 17, 17 × 16, 17 × 15.5, and 18 × 16 mm) while typing speed, error, fatigue, preference, forearm muscle activity, and wrist posture were recorded. Results Productivity and usability ratings were significantly worse for the keyboard with 15.5 mm vertical spacing compared to the other keyboards for both groups. There were few significant differences on usability ratings between the other keyboards. Reducing vertical key spacing, from 18 to 17 to 16 mm, had no significant effect on productivity or usability. Conclusions: The findings support the design of keyboards with vertical key spacings of 16, 17, or 18 mm. Applications: These findings may influence keyboard design and standards.

Work involving pipetting is associated with elevated rates of musculoskeletal disorders of the hand and wrist. The purpose of this study was to quantify thumb loading and muscle activity and determine if they varied among pipetting tasks. Fourteen experienced participants performed nine pipetting tasks while surface electromyography was measured for the extensor pollicis brevis, abductor pollicis longus, flexor pollicis longus, and abductor pollicis brevis muscles. For five tasks, participants used a pipette instrumented to measure the thumb force applied to the plunger. High-precision tasks significantly increased static muscle activity but reduced peak thumb force on average 5% as compared with low-precision tasks. Pipetting high-viscosity fluids increased peak thumb forces on average 11% as compared with pipetting low-viscosity fluids. Use of a latch pipette increased muscle activity of three muscles. We conclude that pipette design and pipetting tasks can influence applied thumb force and muscle activity. We recommend that pipettes be designed to limit applied peak forces and that pipette users be instructed in use patterns that will reduce applied forces. Actual or potential applications of this research include modifications to pipette designs and worker training in order to reduce hand pain associated with pipetting.

Objective The aim was to systematically evaluate the usability of all public electric vehicles (EV) direct current fast chargers (DCFC) in the San Francisco region. Background To achieve a rapid transition to EVs, a highly reliable and easy to use charging infrastructure is critical to building confidence among consumers. Methods The functionality and usability of all 182 open, public DCFC charging stations with CCS connectors (combined charging system) in the 9 counties of the Bay Area were tested (655 electric vehicle service equipment (EVSE) ports). An EVSE was classified as functional if it charged an EV for 2 minutes. Results Overall, 73.3% of the 655 EVSEs were functional. The causes of the nonfunctioning EVSEs (23.5%) were blank or unresponsive screens or error messages; payment system failures; charge initiation failures; network failures; or broken connectors. In addition, the cable was too short to reach the EV inlet for 3.2% of the EVSEs. A random sampling of 10% of the EVSEs, approximately 8 days after the first evaluation, found no overall change in functionality. Conclusions The level of functionality found with field testing conflicts with the 95–98% uptime reported by the EV service providers (EVSPs) who operate the EV charging stations. There is a need for precise and verifiable definitions of uptime, downtime, and excluded time, as applied to public EV chargers. Application The level of failure of the existing public EV DCFC charge infrastructure highlights the importance of improving the system design and maintenance to improve adoption of EVs.

Objective: Determine the effects of display viewing distance on both the visual and musculoskeletal systems while the text height is held constant across viewing distances. Background: The distance from the eyes to a computer display may affect visual and neck comfort. If the angular size of the characters remains the same, it is recommended that the display be placed at a farther viewing distance (e.g., 70—100 cm). However, in common usage, the character sizes are not adjusted based on viewing distance. Method: Participants under the age of 35 years ( N = 24) performed visually demanding tasks using a computer display for 2 hr each at three viewing distances (mean: 52.4, 73.0, and 85.3 cm) while torso and head posture were tracked. At the end of each task, eye accommodation was measured and symptoms were recorded. Results: The near distance was associated with significantly less blurred vision, less dry or irritated eyes, less headache, and improved convergence recovery when compared with the middle and far distances. Participants moved their torsos and heads closer to the monitor at the far distance. Conclusion: If the computer screen character sizes are close to the limits of visual acuity, it is recommended that the computer monitor be positioned between the near (52 cm) and middle (73 cm) distance from the eyes. Application: The location of a computer display should take into account the size of the characters on the screen and the visual acuity of the user.

Objective: The objective was to evaluate the effect of wrist posture on incidence of wrist tendinosis in a prospective cohort of blue-collar workers. Background: Previous studies have identified awkward wrist posture as a risk factor for wrist tendinosis, though the magnitude of the relationship is unclear. Method: Workers ( N = 413) at four industries were followed for up to 28 months with questionnaires and physical examinations every 4 months. Individualized exposure assessments of wrist posture were based on video analysis to determine the wrist extension/flexion angle for up to four tasks. Posture measures were calculated while in "heavy pinch" (> 1 kg force), "heavy power grip" (> 4 kg force), and across "all grips." A proportional hazards model estimated the relationship between time-weighted average posture measures and incidence of dominant-side wrist tendinosis. Results: In a model based on tertiles of exposure, adjusted for age, gender, hand force, and repetition of exertions, risk of tendinosis more than doubled in the highest category (HR = 2.69, 95% CI = 1.01–7.21) across all grips. The relative risk was highest during heavy pinch (HR = 5.03, 95% CI = 0.74–34.05), though not statistically significant. Increased median wrist extension while in heavy power grip was protective (HR = 0.24, 95% CI = 0.06–0.94). Conclusion: In this study of production workers, median wrist flexion of more than 7°, across all grips, was associated with an increased risk of tendinosis. The protective findings on median wrist extension during power grip deserve further investigation. Work tasks and tools should be designed to prevent sustained wrist flexion, especially during tasks involving forceful pinch.

Objective: To develop work guidelines for wrist posture based on carpal tunnel pressure. Background: Wrist posture is considered a risk factor for distal upper extremity musculoskeletal disorders, and sustained wrist deviation from neutral at work may be associated with carpal tunnel syndrome. However, the physiologic basis for wrist posture guidelines at work is limited. Methods: The relationship of wrist posture to carpal tunnel pressure was examined in 37 healthy participants. The participants slowly moved their wrists in extension-flexion and radioulnar deviation while wrist posture and carpal tunnel pressure were recorded. The wrist postures associated with pressures of 25 and 30 mmHg were identified for each motion and used to determine the 25th percentile wrist angles (the angles that protect 75% of the study population from reaching a pressure of 25 or 30 mmHg). Results: Using 30 mmHg, the 25th percentile angles were 32.7° (95% confidence interval [CI] = 27.2°—38.1°) for wrist extension, 48.6° (37.7°—59.4°) for flexion, 21.8° (14.7°—29.0°) for radial deviation, and 14.5° (9.6°—19.4°) for ulnar deviation. For 25 mmHg, the 25th percentile angles were 26.6° and 37.7° for extension and flexion, with radial and ulnar deviation being 17.8° and 12.1°, respectively. Conclusion: Further research can incorporate the independent contributions of pinch force and finger posture into this model. Application: The method presented can provide wrist posture guidelines for the design of tools and hand-intensive tasks.

A laboratory study was conducted to determine the effects of work pace on typing force, electromyographic (EMG) activity, and subjective discomfort. We found that as participants typed faster, their typing force and finger flexor and extensor EMG activity increased linearly. There was also an increase in subjective discomfort, with a sharp threshold between participants' self-selected pace and their maximum typing speed. The results suggest that participants self-select a typing pace that maximizes typing speed and minimizes discomfort. The fastest typists did not produce significantly more finger flexor EMG activity but did produce proportionately less finger extensor EMG activity compared with the slower typists. We hypothesize that fast typists may use different muscle recruitment patterns that allow them to be more efficient than slower typists at striking the keys. In addition, faster typists do not experience more discomfort than slow typists. These findings show that the relative pace of typing is more important than actual typing speed with regard to discomfort and muscle activity. These results suggest that typists may benefit from skill training to increase maximum typing speed. Potential applications of this research includes skill training for typists.