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NASA NTRS2010

Countermeasures (iRED, ARED CEVIS, MEC, TVIS, T2, Periodic Fitness Evaluation, BP-ECG, HRM). Critical Readiness Review Increment 23 and 24

This slide presentation reviews attempts to counteract the effects of being in space. It includes information on the Resistive Exercise Device (RED), the Advanced Resistive Exercise Device (ARED), Cycle Ergometer with Vibration Isolation and Stabilization (CEVIS), Treadmill with Vibration Isolation and Stabilization (TVIS) and periodic fitness evaluation with specific information on BP/ECG, heart rate monitor 2 and data distribution.

Toder, Carly↗
NASA NTRS2010

Flight Rules Critical Readiness Review

The increment 23/24 Critical Readiness Review (CRR) flight rules are presented. The topics include: 1) B13-152 Acoustic Constraints; 2) B13-113 IFM/Corrective Action Prioritization Due to Loss of Exercise Capability; 3) B13-116 Constraints on Treadmill VIS Failure; 4) B13-201 Medical Management of ISS Fire/Smoke Response; 5) ARED and T2 Exercise constraints Flight rules (flight and stage specific); 6) FYI: B14 FR to be updated with requirement to sample crew sleep locations prior to receiving a "recommendation" from SRAG on where to sleep.

Kim, E.↗
NASA NTRS2010

Geolab in NASA's First Generation Pressurized Excursion Module: Operational Concepts

We are building a prototype laboratory for preliminary examination of geological samples to be integrated into a first generation Habitat Demonstration Unit-1/Pressurized Excursion Module (HDU1-PEM) in 2010. The laboratory GeoLab will be equipped with a glovebox for handling samples, and a suite of instruments for collecting preliminary data to help characterize those samples. The GeoLab and the HDU1-PEM will be tested for the first time as part of the 2010 Desert Research and Technology Studies (DRATS), NASAs annual field exercise designed to test analog mission technologies. The HDU1-PEM and GeoLab will participate in joint operations in northern Arizona with two Lunar Electric Rovers (LER) and the DRATS science team. Historically, science participation in DRATS exercises has supported the technology demonstrations with geological traverse activities that are consistent with preliminary concepts for lunar surface science Extravehicular Activities (EVAs). Next years HDU1-PEM demonstration is a starting point to guide the development of requirements for the Lunar Surface Systems Program and test initial operational concepts for an early lunar excursion habitat that would follow geological traverses along with the LER. For the GeoLab, these objectives are specifically applied to enable future geological surface science activities. The goal of our GeoLab is to enhance geological science returns with the infrastructure that supports preliminary examination, early analytical characterization of key samples, insight into special considerations for curation, and data for prioritization of lunar samples for return to Earth.

Evans, C. A.↗
NASA NTRS2010

Professor Created On-line Biology Laboratory Course

This paper will share the creation, implementation, and modification of an online college level general biology laboratory course offered for non-science majors as a part of a General Education Curriculum. The ability of professors to develop quality online laboratories will address a growing need in Higher Education as more institutions combine course sections and look for suitable alternative course delivery formats due to declining departmental budgets requiring reductions in staffing, equipment, and supplies. Also, there is an equal or greater need for more professors to develop the ability to create online laboratory experiences because many of the currently available online laboratory course packages from publishers do not always adequately parallel on-campus laboratory courses, or are not as aligned with the companion lecture sections. From a variety of scientific simulation and animation web sites, professors can easily identify material that closely fit the specific needs of their courses, instructional environment, and students that they serve. All too often, on-campus laboratory courses in the sciences provide what are termed confirmation experiences that do NOT allow students to experience science as would be carried out by scientists. Creatively developed online laboratory experiences can often provide the type of authentic investigative experiences that are not possible on-campus due to the time constraints of a typical two-hour, once-per-week-meeting laboratory course. In addition, online laboratory courses can address issues related to the need for students to more easily complete missing laboratory assignments, and to have opportunities to extend introductory exercises into more advanced undertakings where a greater sense of scientific discovery can be experienced. Professors are strongly encourages to begin creating online laboratory exercises for their courses, and to consider issues regarding assessment, copyrights, and Intellectual Property concerns.

Bowman, Arthur W.↗
NASA NTRS2010

Aerobic Capacity Following Long Duration International Spaces Station (ISS) Missions: Preliminary Results

Maximum oxygen uptake (VO2max) is reduced immediately following space flights lasting <15 d, but has not been measured following long-duration missions. The purpose of this study is to measure VO2max and maximum work rate (WRmax) data from astronauts following ISS flights (91 to 188 d). Methods: Five astronauts [3 M, 2 F: 47+/-6 yr, 174+/-6 cm, 71.9+/-10.9 kg (mean +/- SD)] have participated in the study. Subjects performed upright cycle exercise tests to symptom-limited maximum. An initial test was done approx.270 d before flight to establish work rates for subsequent tests. Subsequent tests, conducted approx.45 d before flight and repeated on the first or second day (R+1/2) and at approx.10 d (R+10) following landing, consisted of 3 5 min stages designed to elicit 25%, 50%, and 75% of preflight VO2max, followed by 25 W(dot)/min increases. VO2, WR, and heart rate (HR) were measured using the ISS Portable Pulmonary Function System [Damec, Odense, DK]. Descriptive statistics are reported. Results: On R+1/2 mean VO2max decreased compared to preflight (Pre: 2.98+/-0.99, R+1/2: 2.63+/-0.56 L(dot)/min); 4 of 5 subjects demonstrated a loss of > 6%. WRmax also decreased on R+1/2 compared to preflight (Pre: 245+/-69, R+1/2: 210+/-45 W). On R+10, VO2max was 2.86+/-0.62 L(dot)/min, with 2 subjects still demonstrating a loss of > 6% from preflight. WRmax on R+10 was 240+/-49 W. HRmax did not change from pre to post-flight. Conclusions: These preliminary results, from the first 5 of 12 planned subjects of an ongoing ISS study, suggest that the majority of astronauts will experience a decrease in VO2max after long-duration space-flight. Interestingly, the two astronauts with the highest preflight VO2max had the greatest loss on R+1/2, and the astronaut with the lowest preflight VO2max increased by 13%. Thus, maintenance of VO2max may be more difficult in astronauts who have a high aerobic capacity, perhaps requiring more intense in-flight exercise countermeasure prescriptions.

Moore, Alan D.↗
NASA NTRS2002

Factors in International Space Station Integration Feasibility Assessments

The International Space Station, ISS, is a growing vehicle. The ISS configuration changes internally and externally with each ISS flight. Each flight adds resources and capabilities such as docking/berthing ports, power, stowage volume, heat rejection, and data processing capability. The configuration, capabilities and performance characteristics of the vehicle will be in flux until assembly complete. At the same time the knowledge about what is required to support humans involved in long duration space flight is also being greatly expanded. In addition to the changes occurring on-orbit, the situation on the ground is also very dynamic. Proposals for new ISS elements, proposed deletions of elements, changes to the ISS requirements, and changes to the planned configuration are always under evaluation. Furthermore, budgetary issues have driven the need to explore alternative options for the ISS . This environment has made the role of the technical integrator in the ISS program unique in that the baseline against which proposals are evaluated is always changing. The nature of the International Space Station Program adds another dimension to the integrators task. ISS program activities are spread across several centers: KSC, MSFC, GRC, DFRC, ARC and JSc. There are six International Partners/participants each with their own unique organizations. The prime contractor is in Texas, California and Alabama. And, the Space Shuttle Program as the launch vehicle provider is another major interface. In spite of the fluidity of the technical baseline, projections and organizational complexity, in the course of evaluating proposals and producing feasibility assessments there are factors, which frequently emerge as significant. These factors tend to be the limiting conditions when they come into play. The finite resources, which tend to limit the options for ISS are: upmass, life support and crew rescue capability, crew time, utilities, exercise equipment, and docking/berthing ports. Upmass requirements need to be developed for each option proposed. Short term and long term impacts to upmass are the result of the implementation and long term operations. The upmass requirements need to be met by the existing launch vehicles and any change in flight rate will be a significant cost driver. In addition, when any item is brought to the ISS careful consideration must be given to the on-board stowage and crew time available to unpack, transfer, stow and use these items. If stowage is not available then something must be returned, use of non-standard stowage negotiated or the item in question stays on the ground. Additional crew time requirements will impact available utilization time or crew off-duty time. When the human element is affected, such as, by increasing the number of crew members or changing the duration of the crew stay (longer or shorter) there is an additional set of factors that come into play. The main considerations are: rescue capability, exercise requirements and availability of equipment, resupply, and life support capability.

Watson, Patricia M.↗
NASA NTRS2004

Innovative Imagery System for Enhanced Habitability Onboard ISS: Desired Features and Possible Hardware Applications

With the advent of the ISS and the experience of Russian, European, and US crewmembers on Mir, the importance of the psychological element in long duration missions is increasingly recognized. An integrated imagery system or Magic Window System could enhance the habitability, performance, and productivity for long term stays in space. Because this is type of system is a new concept for space, functional and technical requirements need to be determined. As part of a three-year project, the functional and technical requirements for an Imagery System onboard the International Space Station (ISS) have been explored. Valuable information was gathered from a survey completed by participants that had been in analog environments (remote/isolated) such as Antarctica, Aquarius, ISS crewmember debriefs, and crew support meetings to identify key functions desired for an integrated Magic Window System. Exercise and medical care activities were identified as areas that could benefit from such a system. It was determined that for exercise, it was worth exploring the concept of displaying a dynamic screen that changes as the crewmember's speed changes while showing physiological measures in a combined display. In terms of enhancing the interfaces for medical care activities, the Magic Window System could show video clips along side procedures for just-in-time training scenarios through a heads-up display. In addition, the portability, usability, and reliability were stressed as important considerations for an integrated system of technologies or Magic Window System. In addition, a review of state-of-the-art screens and other existing technologies such as tablet PCs and Personal Digital Assistants (PDAs) was conducted and contributed to defining technical requirements and feasibility of systems. Some heuristic evaluations of large displays and PDAs were conducted. Finally, feasibility for implementation onboard ISS has been considered. Currently, specific headset units are undergoing usability testing. The outcome of these activities will be valuable to determine the best candidates for an integrated system that could accommodate different needs depending on task.

Whitmore, Mihriban↗
NASA NTRS2011

Extreme Tele-Echocardiography: Methodology for Remote Guidance of In-flight Echocardiography Aboard the International Space Station

Echocardiography is ideally suited for cardiovascular imaging in remote environments, but the expertise to perform it is often lacking. In 2001, an ATL HDI5000 was delivered to the International Space Station (ISS). The instrument is currently being used in a study to investigate the impact of long-term microgravity on cardiovascular function. The purpose of this report is to describe the methodology for remote guidance of echocardiography in space. Methods: In the year before launch of an ISS mission, potential astronaut echocardiographic operators participate in 5 sessions to train for echo acquisitions that occur roughly monthly during the mission, including one exercise echocardiogram. The focus of training is familiarity with the study protocol and remote guidance procedures. On-orbit, real-time guidance of in-flight acquisitions is provided by a sonographer in the Telescience Center of Mission Control. Physician investigators with remote access are able to relay comments on image optimization to the sonographer. Live video feed is relayed from the ISS to the ground via the Tracking and Data Relay Satellite System with a 2 second transmission delay. The expert sonographer uses these images along with two-way audio to provide instructions and feedback. Images are stored in non-compressed DICOM format for asynchronous relay to the ground for subsequent off-line analysis. Results: Since June, 2009, a total of 19 resting echocardiograms and 4 exercise studies have been performed in-flight. Average acquisition time has been 45 minutes, reflecting 26,000 km of ISS travel per study. Image quality has been adequate in all studies, but remote guidance has proven imperative for fine-tuning imaging and prioritizing views when communication outages limit the study duration. Typical resting studies have included 12 video loops and 21 still-frame images requiring 750 MB of storage. Conclusions: Despite limited crew training, remote guidance allows research-quality echocardiography to be performed by non-experts aboard the ISS. Analysis is underway and additional subjects are being recruited to define the impact of microgravity on cardiac structure and systolic and diastolic function.

Martin, David↗
NASA NTRS2011

Mission X: Train Like an Astronaut Pilot Study

Mission X: Train Like an Astronaut is an international educational challenge focusing on fitness and nutrition as we encourage students to "train like an astronaut." Teams of students (aged 8-12) learn principles of healthy eating and exercise, compete for points by finishing training modules, and get excited about their future as "fit explorers." The 18 core exercises (targeting strength, endurance, coordination, balance, spatial awareness, and more) involve the same types of skills that astronauts learn in their training and use in spaceflight. This first-of-its-kind cooperative outreach program has allowed 14 space agencies and various partner institutions to work together to address quality health/fitness education, challenge students to be more physically active, increase awareness of the importance of lifelong health and fitness, teach students how fitness plays a vital role in human performance for exploration, and inspire and motivate students to pursue careers in STEM fields. The project was initiated in 2009 in response to a request by the International Space Life Sciences Working Group. USA, Netherlands, Italy, France, Germany, Austria, Colombia, Spain, and United Kingdom hosted teams for the pilot this past spring, and Japan held a modified version of the challenge. Several more agencies provided input into the preparations. Competing on 131 teams, more than 3700 students from 40 cities worldwide participated in the first round of Mission X. OUTCOMES AND BEST PRACTICES Members of the Mission X core team will highlight the outcomes of this international educational outreach pilot project, show video highlights of the challenge, provide the working group s initial assessment of the project and discuss the future potential of the effort. The team will also discuss ideas and best practices for international partnership in education outreach efforts from various agency perspectives and experiences

Lloyd, Charles W.↗
NASA NTRS2003

Adaptive Effects on Locomotion Performance Following Exposure to a Rotating Virtual Environment

During long-duration spaceflight, astronauts experience alterations in vestibular and somatosensory cues that result in adaptive disturbances in balance and coordination upon return to Earth. These changes can pose a risk to crew safety and to mission objectives if nominal or emergency vehicle egress is required immediately following long-duration spaceflight. At present, no operational countermeasure is available to mitigate the adaptive sensorimotor component underlying the locomotor disturbances that occur after spaceflight. Therefore, the goal of this study is to develop an inflight training regimen that facilitates recovery of locomotor function after long-duration spaceflight. The countermeasure we are proposing is based on the concept of adaptive generalization. During this type of training the subject gains experience producing the appropriate adaptive motor behavior under a variety of sensory conditions and response constraints. As a result of this training a subject learns to solve a class of motor problems, rather than a specific motor solution to one problem, i.e., the subject learns response generalizability or the ability to "learn to learn." under a variety of environmental constraints. We are developing an inflight countermeasure built around treadmill exercise activities. By manipulating the sensory conditions of exercise by varying visual flow patterns, body load and speed we will systematically and repeatedly promote adaptive change in locomotor behavior. It has been shown that variable practice training increases adaptability to novel visuo-motor situations. While walking over ground in a stereoscopic virtual environment that oscillated in roll, subjects have shown compensatory torso rotation in the direction of scene rotation that resulted in positional variation away from a desired linear path. Thus, postural sway and locomotor stability in 1-g can be modulated by visual flow patterns and used during inflight treadmill training to promote adaptive generalization. The purpose of this study was to determine if adaptive modification in locomotor performance could be achieved by viewing simulated self-motion in a passive-immersive virtual ' environment over a prolonged period during treadmill locomotion.

Mulavara, A. P.↗
NASA NTRS2011

Supersonics/Airport Noise Plan: An Evolutionary Roadmap

This presentation discusses the Plan for the Airport Noise Tech Challenge Area of the Supersonics Project. It is given in the context of strategic planning exercises being done in other Projects to show the strategic aspects of the Airport Noise plan rather than detailed task lists. The essence of this strategic view is the decomposition of the research plan by Concept and by Tools. Tools (computational, experimental) is the description of the plan that resources (such as researchers) most readily identify with, while Concepts (here noise reduction technologies or aircraft configurations) is the aspects that project management and outside reviewers most appreciate as deliverables and milestones. By carefully cross-linking these so that Concepts are addressed sequentially (roughly one after another) by researchers developing/applying their Tools simultaneously (in parallel with one another), the researchers can deliver milestones at a reasonable pace while doing the longer-term development that most Tools in the aeroacoustics science require. An example of this simultaneous application of tools was given for the Concept of High Aspect Ratio Nozzles. The presentation concluded with a few ideas on how this strategic view could be applied to the Subsonic Fixed Wing Project's Quiet Aircraft Tech Challenge Area as it works through its current roadmapping exercise.

Bridges, James↗
NASA NTRS2011

NASA Musculoskeletal Space Medicine and Reconditioning Program

The Astronaut Strength, Conditioning, and Rehabilitation (ASCR) group is comprised of certified strength and conditioning coaches and licensed and certified athletic trainers. The ASCR group works within NASA s Space Medicine Division providing direction and supervision to the astronaut corp with regards to physical readiness throughout all phases of space flight. The ASCR group is overseen by flight surgeons with specialized training in sports medicine or physical medicine and rehabilitation. The goals of the ASCR group include 1) designing and administering strength and conditioning programs that maximize the potential for physical performance while minimizing the rate of injury, 2) providing appropriate injury management and rehabilitation services, 3) collaborating with medical, research, engineering, and mission operations groups to develop and implement safe and effective in-flight exercise countermeasures, and 4) providing a structured, individualized post-flight reconditioning program for long duration crew members. This Panel will present the current approach to the management of musculoskeletal injuries commonly seen within the astronaut corp and will present an overview of the pre-flight physical training, in-flight exercise countermeasures, and post-flight reconditioning program for ISS astronauts.

Kerstman, Eric↗
NASA NTRS2011

Deployment of an Advanced Electrocardiographic Analysis (A-ECG) to Detect Cardiovascular Risk in Career Firefighters

INTRODUCTION: Sudden cardiac death is the leading cause of line of duty death among firefighters, accounting for approximately 45% of fatalities annually. Firefighters perform strenuous muscular work while wearing heavy, encapsulating personal protective equipment in high ambient temperatures, under chaotic and emotionally stressful conditions. These factors can precipitate sudden cardiac events like myocardial infarction, serious dysrhythmias, or cerebrovascular accidents in firefighters with underlying cardiovascular disease. PURPOSE: The purpose of this study was to deploy and then evaluate the contribution of resting advanced ECG (A-ECG) in addition to other screening tools (family history, lipid profiles, and cardiopulmonary exercise tests, XT) in assessment of an individual fs cardiac risk profile. METHODS: Forty-four career firefighters were recruited to perform comprehensive baseline assessments including tests of aerobic performance, fasting lipids and glucose. Five-min resting 12-lead A-ECGs were obtained in a subset of firefighters (n=21) and transmitted over a secure networked system to a NASA physician collaborator. Using myocardial perfusion and other imaging as the gold standard, A-ECG scoring has been proven useful in accurately identifying a number of cardiac pathologies including coronary artery disease (CAD), left ventricular hypertrophy, hypertrophic cardiomyopathy, and non-ischemic and ischemic cardiomyopathy. RESULTS: Subjects f mean (SD) age was 43 (8) years, weight 91 (13) kg, and BMI 28 (3) kg/m2. Fifty-one percent of subjects had .3 cardiovascular risk factors. One subject had ST depression on XT ECG, at least one positive A-ECG score for CAD, and documented CAD based on cardiology referral. While all other subjects, including those with fewer risk factors, higher aerobic fitness, and normal exercise ECGs, were classified as healthy by A-ECG, there was no trend for association between risk factors and any of 20 A-ECG parameters in the grouped data.

Dolezal, B. A.↗
NASA NTRS2011

Near-Infrared Spectroscopic Measurement of the Effect of Leg Dominance on Muscle Oxygen Saturation During Cycling

The effect of leg dominance on the symmetry of the biomechanics during cycling remains uncertain -- asymmetries have been observed in kinematics and kinetics, while symmetries were found in muscle activation. No studies have yet investigated the symmetry of muscle metabolism during cycling. Near-infrared spectroscopy (NIRS) provides a non-invasive method to investigate the metabolic responses of specific muscles during cycling. PURPOSE: To determine whether there was an effect of leg dominance on thigh muscle oxygen saturation (SmO2) during incrementally loaded submaximal cycling using NIRS. METHODS: Eight right leg dominant, untrained subjects (5 men, 3 women; 31+/-2 yrs; 168.6+/-1.0 cm; 67.2+/-1.8 kg, mean +/- SE) volunteered to participate. Spectra were collected bilaterally from the vastus lateralis (VL) during supine rest and cycling. SmO2 was calculated using previously published methods. Subjects pedaled at 65 rpm while resistance to pedaling was increased in 0.5 kp increments from 0.5 kp every 3 min until the subject reached 80% of age-predicted maximal heart rate. SmO2 was averaged over 3 min for each completed stage. A two-way ANOVA was performed to test for leg differences. A priori contrasts were used to compare work levels to rest. RESULTS: VL SmO2 was not different between the dominant and non-dominant legs at rest and during exercise (p=0.57). How SmO2 changed with workload was also not different between legs (p=0.32). SmO2 at 0.5 kp (60.3+/-4.0, p=0.12) and 1.0 kp (59.5+/-4.0, p=0.10) was not different from rest (69.1+/-4.0). SmO2 at 1.5 kp (55.4 4.0, p=0.02), 2.0 kp (55.7+/-5.0, p=0.04), and 2.5 kp (43.4+/-7.9, p=0.01) was significantly lower than rest. CONCLUSION: VL SmO2 during cycling is not different between dominant and non-dominant legs and decreases with moderate workload in untrained cyclists. Assuming blood flow is directed equally to both legs, similar levels of oxygen extraction (as indicated by SmO2) suggests the metabolic load of cycling is not different between legs. This is in agreement with a recent study demonstrating symmetrical increase of muscle activation of the VL during cycling. Leg dominance did not influence VL SmO2 during submaximal cycling, but may have an effect at higher loads or during other forms of exercise, such as walking and running.

Ellerby, Gwenn E. C.↗
NASA NTRS2003

Software for Training in Pre-College Mathematics

The Intelligent Math Tutor (IMT) is a computer program for training students in pre-college and college-level mathematics courses, including fundamentals, intermediate algebra, college algebra, and trigonometry. The IMT can be executed on a server computer for access by students via the Internet; alternatively, it can be executed on students computers equipped with compact- disk/read-only-memory (CD-ROM) drives. The IMT provides interactive exercises, assessment, tracking, and an on-line graphing calculator with algebraic-manipulation capabilities. The IMT provides an innovative combination of content, delivery mechanism, and artificial intelligence. Careful organization and presentation of the content make it possible to provide intelligent feedback to the student based on performance on exercises and tests. The tracking and feedback mechanisms are implemented within the capabilities of a commercial off-the-shelf development software tool and are written in the Unified Modeling Language to maximize reuse and minimize development cost. The graphical calculator is a standard feature of most college and pre-college algebra and trigonometry courses. Placing this functionality in a Java applet decreases the cost, provides greater capabilities, and provides an opportunity to integrate the calculator with the lessons.

Shelton, Robert O.↗
NASA NTRS2012

Astronaut Biography Project for Countermeasures of Human Behavior and Performance Risks in Long Duration Space Flights

This final report will summarize research that relates to human behavioral health and performance of astronauts and flight controllers. Literature reviews, data archival analyses, and ground-based analog studies that center around the risk of human space flight are being used to help mitigate human behavior and performance risks from long duration space flights. A qualitative analysis of an astronaut autobiography was completed. An analysis was also conducted on exercise countermeasure publications to show the positive affects of exercise on the risks targeted in this study. The three main risks targeted in this study are risks of behavioral and psychiatric disorders, risks of performance errors due to poor team performance, cohesion, and composition, and risks of performance errors due to sleep deprivation, circadian rhythm. These three risks focus on psychological and physiological aspects of astronauts who venture out into space on long duration space missions. The purpose of this research is to target these risks in order to help quantify, identify, and mature countermeasures and technologies required in preventing or mitigating adverse outcomes from exposure to the spaceflight environment

Banks, Akeem↗
NASA NTRS2012

Managing Science Operations during Planetary Surface Operations at Long Light Delay-Time Targets: The 2011 Desert RATS Test

Desert Research and Technology Studies (Desert RATS) is a multi-year series of hardware and operations tests carried out annually in the high desert of Arizona in the San Francisco Volcanic Field. Conducted since 1997, these activities are designed to exercise planetary surface hardware and operations in conditions where multi-day tests are achievable. Desert RATS 2011 Science Operations Test simulated the management of crewed science operations at targets that were beyond the light delay time experienced during Low-Earth Orbit (LEO) and lunar surface missions, such as a mission to a Near-Earth Object (NEO) or the martian surface. Operations at targets at these distances are likely to be the norm as humans move out of the Earth-Moon system. Operating at these distances places significant challenges on mission operations, as the imposed light-delay time makes normal, two-way conversations extremely inefficient. Consequently, the operations approach for space missions that has been exercised during the first half-century of human space operations is no longer viable, and new approaches must be devised.

Eppler, D. B.↗