Task Performance Time Research Articles

Preferential processing of task-irrelevant beloved-related information and task performance: Two event-related potential studies

People who are in love have better attention for beloved-related information, but report having trouble focusing on other tasks, such as (home)work. So, romantic love can both improve and hurt cognition. Emotional information is preferentially processed, which improves task performance when the information is task-relevant, but hurts task performance when it is task-irrelevant. Because beloved-related information is highly emotional, the effects of romantic love on cognition may resemble these effects of emotion on cognition. We examined whether beloved-related information is preferentially processed even when it is task-irrelevant and whether this hurts task performance. In two event-related potential studies, participants who had recently fallen in love performed a visuospatial short-term memory task. Task-irrelevant beloved, friend, and stranger faces were presented during maintenance (Study 1), or encoding (Study 2). The Early Posterior Negativity (EPN) reflecting early automatic attentional capturing and the Late Positive Potential (LPP) reflecting sustained motivated attention were largest for beloved pictures. Thus, beloved pictures are preferentially processed even when they are task-irrelevant. Task performance and reaction times did not differ between beloved, friend, and stranger conditions. Nevertheless, self-reported obsessive thinking about the beloved tended to correlate negatively with task performance, and positively with reaction times, across conditions. So, although task-irrelevant beloved-related information does not impact task performance, more obsessive thinking about the beloved might relate to poorer and slower overall task performance. More research is needed to clarify why people experience trouble focusing on beloved-unrelated tasks and how this negative effect of love on cognition could be reduced.

Exploring the repetition bias in voluntary task switching.

In the voluntary task-switching paradigm, participants are required to randomly select tasks. We reasoned that the consistent finding of a repetition bias (i.e., participants repeat tasks more often than expected by chance) reflects reasonable adaptive task selection behavior to balance the goal of random task selection with the goals to minimize the time and effort for task performance. We conducted two experiments in which participants were provided with variable amount of preview for the non-chosen task stimuli (i.e., potential switch stimuli). We assumed that switch stimuli would initiate some pre-processing resulting in improved performance in switch trials. Results showed that reduced switch costs due to extra-preview in advance of each trial were accompanied by more task switches. This finding is in line with the characteristics of rational adaptive behavior. However, participants were not biased to switch tasks more often than chance despite large switch benefits. We suggest that participants might avoid effortful additional control processes that modulate the effects of preview on task performance and task choice.

Feedback Frequency Effect on Performance Time in Dynamic Decision Making Task

Decision support such as feedback has been considered to be crucial for successful work in many important Dynamic Decision Making (DDM) tasks. However, previous research did not consider the effect of feedback frequency on the performance time which, in conjunction with accuracy, is an important measure of the task performance evaluation in DDM. Therefore, in order to accurately evaluate task performance in a DDM, not only the accuracy of performance, but also the time to perform the task should be considered. This paper will examine the effect of feedback frequency on the task performance time in DDM. Drawing from activation theory (Anderson, 2009), we hypothesized that frequent feedback induces cognitive overload, resulting in learning degradation, and thus producing a U-shaped relationship with performance time. In order to test this hypothesis, we have experimented with the DDM simulation where the frequency of feedback was manipulated. The results demonstrate that there is U-shaped relationship between feedback frequency and performance time ( R2= 0.746, p < 0.01). Our findings show that providing excessively frequent feedback to an operator negatively affects performance time.

Effect of Continuous Motion Parameter Feedback on Laparoscopic Simulation Training: A Prospective Randomized Controlled Trial on Skill Acquisition and Retention

To investigate the effect of motion parameter feedback on laparoscopic basic skill acquisition and retention during a standardized box training curriculum. A Lap-X Hybrid laparoscopic simulator was designed to provide individual and continuous motion parameter feedback in a dry box trainer setting. In a prospective controlled trial, surgical novices were randomized into 2 groups (regular box group, n = 18, and Hybrid group, n = 18) to undergo an identical 5-day training program. In each group, 7 standardized tasks on laparoscopic basic skills were completed twice a day on 4 consecutive days in fixed pairs. Additionally, each participant performed a simulated standard laparoscopic cholecystectomy before (day 1) and after training (day 5) on a LAP Mentor II virtual reality (VR) trainer, allowing an independent control of skill progress in both groups. A follow-up assessment of skill retention was performed after 6 weeks with repetition of both the box tasks and VR cholecystectomy. Muenster University Hospital Training Center, Muenster, Germany. Medical students without previous surgical experience. Laparoscopic skills in both groups improved significantly during the training period, measured by the overall task performance time. The 6 week follow-up showed comparable skill retention in both groups. Evaluation of the VR cholecystectomies demonstrated significant decrease of operation time (p < 0.01), path length of the left and right instrument, and the number of movements of the left and right instruments for the Hybrid group (all p < 0.001), compared to the box group. Similar results were found at the assessment of skill retention. Simulation training on both trainers enables reliable acquisition of laparoscopic basic skills. Furthermore, individual and continuous motion feedback improves laparoscopic skill enhancement significantly in several aspects. Thus, training systems with feedback of motion parameters should be considered to achieve long-term improvement of motion economy among surgical trainees.

Occupational Specific Strength Testing Enhances the Prediction of Astronaut Related Task Performance

Future space missions beyond low earth orbit will require deconditioned astronauts to perform occupationally relevant tasks while confined within a spacesuit of significant mass. The prediction of task performance times under these conditions will be critical for crew safety, autonomous operations, and mission success. PURPOSE: Determine if the addition of task specific upper body strength testing to current National Aeronautics and Space Administration’s (NASA) standard lower body testing would enhance the prediction of time-to-completion in a test battery designed to simulate astronaut related occupational tasks. METHODS: Eight, healthy participants of astronaut age (34.9 ± 3.7 years) completed six occupationally relevant tasks while wearing a 48-kg weighted suit designed to emulate the weight distribution of the NDX-2 planetary spacesuit. The six tasks performed were: hatch opening, hand drilling, construction wrenching, half-mile walk, collecting weighted samples, and dragging an unresponsive crewmember to safety. The time-to-complete each task was recorded and summed to obtain a total time for the test battery. In addition to the standard knee extensor-flexor strength and endurance tests employed at the NASA Johnson Space Center for crew health testing, task specific isometric strength was collected prior to each task for hatch opening, hand drilling, and wrenching, Linear regression was used to predict the dependent variable of total time-to-completion with two independent variable models 1): NASA upper leg standard measures alone and 2): NASA upper leg standard measures + task specific isometric testing for wrenching and hand drilling. RESULTS: Total time-to-completion of the test battery ranged from 20.2-44.5 minutes. NASA upper leg standard measures alone accounted for 61.5% of the variability in time-to-completion (p = 0.15). The addition of hand drilling and wrenching testing to NASA upper leg standard measures accounted for 99.6% of the variability in time-to-completion (p = 0.047). CONCLUSION: Adding occupational specific strength tests (hand drilling and wrenching) to NASA’s standard lower extremity tests successfully predicted time-to-completion of a performance test battery within a weighted suit in 1G. Supported by ND NASA ESPCoR

ICloud 캘린더와 네이버 캘린더의 사용성 평가 -모바일 애플리케이션을 중심으로-

스마트폰 사용이 대중화되어감으로써 스마트폰을 중심으로 형성되고 있는 스마트미디어환경은 새로운 생태계를 구축하고 있다. 본 연구는 스마트폰과 애플리케이션의 보급과 사용이 증가함에 따라서 오프라인에서 온라인화되어가는 요소들의 사용성을 평가하고 지속사용요소들을 알아보는 데 목적이 있다. 이를 위해 애플리케이션 사용성 비교에 관한 선행연구들을 분석하여 가설을 설정하고, 대표적인 캘린더 애플리케이션인 iCloud 캘린더와 네이버 캘린더의 사용성을 평가하기 위해 스마트폰 사용자들을 대상으로 두 캘린더 애플리케이션의 심층인터뷰를 시행하고 태스크 수행시간을 분석하여 설정한 가설을 분석하였다. 설정한 가설을 검증하며 심미성에 중점을 두는 사용자는 어떤 요소를 중요시하는지, 사용성과 실용성에 중점을 두는 사용자는 어떤 요소를 중요시하는지 형태별로 분석하였다. 향후 애플리케이션 개발의 '실패와 성공' 요소를 분석하여 향후 다른 온라인화가 되어가는 콘텐츠의 성공적인 발전을 위해 본 연구를 진행하게 되었다. Since usage of smartphone becomes popular, Ecology of smart media based on smartphone is creating new ecological system of information. This research is for evaluating usability and sustainability of application due to development of smartphone usage in these days. For the research, precedent researches were analyzed and hypothesis were set up based on those researches. Then, iCloud Calendar and Never Calendar, which are two major calendar applications, were evaluated by in-depth interview and measuring task performance time of interviewees, and used these results to verify hypothesis. Then verify hypothesis through the research and analyze which type of users focus on aesthetic impression, and which users focus on usability and practicality. This research is to analyze success and failure points of Calendar Applications' user experience design, and suggests guideline for future transformation of offline to online.

Analysis of human–robot interaction at the DARPA Robotics Challenge Finals

In June 2015, the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge (DRC) Finals were held in Pomona, California. The DRC Finals served as the third phase of the program designed to test the capabilities of semi-autonomous, remote humanoid robots to perform disaster response tasks with degraded communications. All competition teams were responsible for developing their own interaction method to control their robot. Of the 23 teams in the competition, 20 consented to participate in this study of human–robot interaction (HRI). The evaluation team observed the consenting teams during task execution in their control rooms (with the operators), and all 23 teams were observed on the field during the public event (with the robot). A variety of data were collected both before the competition and on-site. Each participating team’s interaction methods were distilled into a set of characteristics pertaining to the robot, operator strategies, control methods, and sensor fusion. Each task was decomposed into subtasks that were classified according to the complexity of the mobility and/or manipulation actions being performed. Performance metrics were calculated regarding the number of task attempts, performance time, and critical incidents, which were then correlated to each team’s interaction methods. The results of this analysis suggest that a combination of HRI characteristics, including balancing the capabilities of the operator with those of the robot and multiple sensor fusion instances with variable reference frames, positively impacted task performance. A set of guidelines for designing HRI with remote, semi-autonomous humanoid robots is proposed based on these results.

Differences in attention, hand dexterity, and lower extremity activities in the presence or absence of a time limit.

[Purpose] The purpose of this study was to investigate how a time limit affects day-to-day tasks such as attention, hand dexterity, and sit to standing and sitting activity. The grounds for using a time limit as a method of learning tasks related to daily living are examined based on the results of this investigation. [Subjects and Methods] The subjects consisted of 51 healthy college students (20 males and 31 females). The task performance time for SESSION 1, in which there was no time limit, was measured and the task duration privately recorded. The task performance for SESSION 2 was then measured with a time limit of the same duration as the time recorded for SESSION 1. Attention was measured using the trail-making test, hand dexterity using the Purdue pegboard test, and lower extremity activity using the sit to standing and sitting test. [Results] The levels for the attention, hand dexterity, and lower extremity activities were high in the environment in which a time limit was set. The differences between the genders depending on the presence or absence of a time limit was insignificant. [Conclusion] A time limit environment can be used as a task-training method for attention, hand dexterity, and lower extremity activities

Design and Evaluation of an Accessible Academic Course Search Portal

Background This paper presents the design and development of an accessible acedemic course search portal. In particular accessibilty features related to the capabilities of the device used to access the portal (desktop vs mobile) as well as capabilities of the end users (such as disabled users) are considered. The continued growing population of students with disabilities and increasing use of mobile devices make both of these important considerations in providing equitable access to critical services for a diverse student population. Methods An alternative academic course search interface was designed that incorporates a mobile-first design approach combined with current universal design principles and best practices. Participants with varying levels of ability/disability evaluated both portals in terms of effectiveness, efficiency, subjective satisfaction and learnability using the System Usability Survey. Task times, efficiency and errors were also recoreded. Results Within subjects paired t-tests comparing the current portal with the new design showed significant improvements in task performance time and accuracy. Overall usability scores for the new portal design were also significantly better. Conclusions The results indicate that the application of these principles can lead to significant imporvements in overall usability, effectiveness and task efficiency within a single interface that is designed to be appropriate for both mobile and desktop access.

Effects of Head-Mounted Display (HMD) Position on Procedure Following Tasks and Usability

Background Head-mounted displays (HMDs) have found value in industrial applications as aids in performing long and/or complicated procedural tasks. Currently, there are gaps in understanding the impact of various design characteristics on the performance of tasks aided by HMDs. This study investigated how different positioning of head mounted displays affected the performance of workers during procedure following tasks. Methods Eight car maintenance tasks were performed by 20 participants with task guidance presented at four display conditions: above-eye, eye-centered, below-eye and via traditional paper manual. Task times, errors were measured and user experience measurements were collected. Results The results showed that none of the display conditions had significant effects on completion times. However, below-eye display outperformed the above-eye display condition for tasks requiring participants to perform assessments. User experience ratings showed that the eye-central condition was the most preferred display position among the three HMD conditions. Conclusions A non-transparent, monocular HMD that partially blocks a user’s FoV was not observed to significantly decrease overall task performance time. In support of previous findings, an HMD positioned below the eye outperformed the above-eye position for assess actions in this study. User overreliance on the instructions provided via HMD was also observed in this study. In a slightly different finding from previous studies, users indicated that the eye-central HMD position provided the best overall experience and was the most preferred by participants in this study.

Why are they late? Timing abilities and executive control among students with learning disabilities

While a deficient ability to perform daily tasks on time has been reported among students with learning disabilities (LD), the underlying mechanism behind their ‘being late' is still unclear. This study aimed to evaluate the organization in time, time estimation abilities, actual performance time pertaining to specific daily activities, as well as the executive functions of students with LD in comparison to those of controls, and to assess the relationships between these domains among each group. The participants were 27 students with LD, aged 20–30, and 32 gender and age-matched controls who completed the Time Organization and Participation Scale (TOPS) and the Behavioral Rating Inventory of Executive Function-Adult version (BRIEF-A). In addition, their ability to estimate the time needed to complete the task of preparing a cup of coffee as well as their actual performance time were evaluated. The results indicated that in comparison to controls, students with LD showed significantly inferior organization in time (TOPS) and executive function abilities (BRIEF-A). Furthermore, their time estimation abilities were significantly inferior and they required significantly more time to prepare a cup of coffee. Regression analysis identified the variables that predicted organization in time and task performance time among each group. The significance of the results for both theoretical and clinical implications are discussed.What this paper adds?This study examines the underlying mechanism of the phenomena of being late among students with LD. Following a recent call for using ecologically valid assessments, the functional daily ability of students with LD to prepare a cup of coffee and to organize time were investigated. Furthermore, their time estimation and executive control abilities were examined as a possible underlying mechanism for their lateness. Although previous studies have indicated executive control deficits among students with LD, to our knowledge, this is the first analysis of the relationships between their executive control and time estimation deficits and their influence upon their daily function and organization in time abilities. Our findings demonstrate that students with LD need more time in order to execute simple daily activities, such as preparing a cup of coffee. Deficient working memory, retrospective time estimation ability and inhibition predicted their performance time and organization in time abilities. Therefore, this paper sheds light on the mechanism behind daily performance in time among students with LD and emphasizes the need for future development of focused intervention programs to meet their unique needs.

The Effects of Performance Fatigability on Postural Control and Rehabilitation in the Older Patient.

Fatigue is common in older adults and has a significant effect on quality of life. Despite the high prevalence of fatigue in older individuals, several aspects are poorly understood. It is important to differentiate subjective fatigue complaints from fatigability of motor performance because the two are independent constructs with potentially distinct consequences on mobility. Performance fatigability is the magnitude of change in a performance criterion over a given time of task performance. Performance fatigability is a compulsory element of any strength training program, yet strength training is an important component of rehabilitation programs for older adults. The consequences of fatigability for older adults suggest that acute exercise of various types may result in acute impairments in postural control. The effects of performance fatigability on postural control in older adults are evaluated here to aid the rehabilitation clinician in making recommendations for evaluation of fall risks and exercise prescription.

Assembly line balancing problem with task learning and dynamic task reassignment

This paper addresses an existing but unsolved problem: dynamic task reassignment under changing task performance times. This situation is relevant to automated flexible assembly systems with collaborative learning. The length of the line can be reduced during the period of production by dynamically rebalancing the assembly line because of the changing task times. A task reassignment procedure is designed to balance such an assembly line where task times are being reduced during small lot size production. Backward induction rules, which can be combined with prevalent algorithms, are proposed to form such a procedure. A case study is provided to show that the procedure significantly increases the efficiency of the assembly line in terms of the length of the production line and system idle times.

Learning and Memory in Juvenile Zebrafish: What makes the Difference – Population or Rearing Environment?

AbstractThe ability to learn and remember about the surrounding environment is crucial for the survival of organisms in their natural habitats. Adults of numerous fish species have been shown to display sophisticated behaviour related to learning and memory. This study deals with testing learning abilities among juveniles (10 wks old) of zebrafish (Danio rerio) through a simple task of finding food. We compared the performance of juveniles from two populations, a wild collected from a natural habitat and an aquarium‐bred purchased from a pet shop, reared in bare environment (lacking visual cues). Additionally, we also tested the effect of early habitat enrichment on the performance among juveniles of the aquarium‐bred population. The experiments involved training fishes to solve a simple maze (with a food reward at the end) and testing their memory. Learning was measured based on the time taken to complete the task (performance time) of finding food in the maze‐arena across repeated trials. Our results showed that juveniles from the two populations possessed significantly different learning abilities. There were population differences in exploratory tendency and time taken to accomplish the task. However, when memory was tested based on performance time between training and test day, individuals (from both populations) were found to be poor at memorizing learnt tasks. On the other hand, juveniles (belonging to aquarium‐bred population) reared in spatially complex environments displayed higher rates of learning and were capable of remembering learnt tasks better than their counterparts from bare environments. This study thus demonstrates the importance of rearing conditions and natural ecology in ontogenetic development of learning and memory functions among zebrafish.

Initial Usability and Feasibility Evaluation of a Personal Health Record-Based Self-Management System for Older Adults

Introduction:Electronic personal health record-based (ePHR-based) self-management systems can improve patient engagement and have an impact on health outcomes. In order to realize the benefits of these systems, there is a need to develop and evaluate heath information technology from the same theoretical underpinnings.Methods: Using an innovative usability approach based in human-centered distributed information design (HCDID), we tested an ePHR-based falls-prevention self-management system—Self-Assessment via a Personal Health Record (i.e., SAPHeR)—designed using HCDID principles in a laboratory. And we later evaluated SAPHeR’s use by community-dwelling older adults at home.Results:The innovative approach used in this study supported the analysis of four components: tasks, users, representations, and functions. Tasks were easily learned and features such as text-associated images facilitated task completion. Task performance times were slow, however user satisfaction was high. Nearly seven out of every ten features desired by design participants were evaluated in our usability testing of the SAPHeR system. The in vivo evaluation suggests that older adults could improve their confidence in performing indoor and outdoor activities after using the SAPHeR system.Discussion/Conclusion:We have applied an innovative consumer-usability evaluation. Our approach addresses the limitations of other usability testing methods that do not utilize consistent theoretically based methods for designing and testing technology. We have successfully demonstrated the utility of testing consumer technology use across multiple components (i.e., task, user, representational, functional) to evaluate the usefulness, usability, and satisfaction of an ePHR-based self-management system.

Development of task analysis method for operator tasks in main control room of an advanced nuclear power plant

Task analysis methods provide an insight for quantitative and qualitative predictions of how people will use a proposed system, though the different versions have different emphases. Most of the methods can attest to the coverage of the functionality of a system and all provide estimates of task performance time. However, most of the tasks that operators deal with in a digital work environment in the main control room of an advanced nuclear power plant require high mental activity. Such mental tasks overlap and must be dealt with at the same time; most of them can be assumed to be highly parallel in nature. Therefore, the primary aim to be addressed in this paper was to develop a method that adopts CPM-GOMS (cognitive perceptual motor-goals operators methods selection rules) as the basic pattern of mental task analysis for the advanced main control room. A within-subjects experiment design was used to examine the validity of the modified CPM-GOMS. Thirty participants participated in two task types, which included high- and low-compatibility types. The results indicated that the performance was significantly higher on the high-compatibility task type than on the low-compatibility task type; that is, the modified CPM-GOMS could distinguish the difference between high- and low-compatibility mental tasks.

Color temperature's impact on task performance and brainwaves of school-age children.

[Purpose] This study investigated color temperature’s impact on task performance. It presents a scientific analysis of brainwave and task performance time changes, and the results of a self-report type survey. [Subjects] Twenty-four elementary school fifth-grade boys and girls with no visual problems participated in the experiment. [Methods] Physiological reaction times of task performance were measured in a laboratory that could fix and maintain color temperature. Brainwave changes and the task performance times were measured, and a self-report questionnaire was conducted in order to measure of emotional reactions. [Results] Regarding the brainwave changes associated with color temperature, alpha waves were emitted in the O2 area when puzzle tasks were illuminated by orange light and low and high beta waves were emitted in the F3 area under white light. Five items (Brilliant, Soft, Lively, Relaxed, Open) were reported predominantly in responses to orange light in the self-report questionnaire. [Conclusion] The results of this study show that relaxation and stability are not assured when the color temperature is low, and that concentration and cognitive activity are not necessarily easier when the color temperature is high. The color temperature change when performing tasks promoted emotional factors more than brainwave, a biological change.

Node, Node-Link, and Node-Link-Group Diagrams: An Evaluation.

Effectively showing the relationships between objects in a dataset is one of the main tasks in information visualization. Typically there is a well-defined notion of distance between pairs of objects, and traditional approaches such as principal component analysis or multi-dimensional scaling are used to place the objects as points in 2D space, so that similar objects are close to each other. In another typical setting, the dataset is visualized as a network graph, where related nodes are connected by links. More recently, datasets are also visualized as maps, where in addition to nodes and links, there is an explicit representation of groups and clusters. We consider these three Techniques, characterized by a progressive increase of the amount of encoded information: node diagrams, node-link diagrams and node-link-group diagrams. We assess these three types of diagrams with a controlled experiment that covers nine different tasks falling broadly in three categories: node-based tasks, network-based tasks and group-based tasks. Our findings indicate that adding links, or links and group representations, does not negatively impact performance (time and accuracy) of node-based tasks. Similarly, adding group representations does not negatively impact the performance of network-based tasks. Node-link-group diagrams outperform the others on group-based tasks. These conclusions contradict results in other studies, in similar but subtly different settings. Taken together, however, such results can have significant implications for the design of standard and domain snecific visualizations tools.

Sequential roles of primary somatosensory cortex and posterior parietal cortex in tactile-visual cross-modal working memory: a single-pulse transcranial magnetic stimulation (spTMS) study.

Both monkey neurophysiological and human EEG studies have shown that association cortices, as well as primary sensory cortical areas, play an essential role in sequential neural processes underlying cross-modal working memory. The present study aims to further examine causal and sequential roles of the primary sensory cortex and association cortex in cross-modal working memory. Individual MRI-based single-pulse transcranial magnetic stimulation (spTMS) was applied to bilateral primary somatosensory cortices (SI) and the contralateral posterior parietal cortex (PPC), while participants were performing a tactile-visual cross-modal delayed matching-to-sample task. Time points of spTMS were 300ms, 600ms, 900ms after the onset of the tactile sample stimulus in the task. The accuracy of task performance and reaction time were significantly impaired when spTMS was applied to the contralateral SI at 300ms. Significant impairment on performance accuracy was also observed when the contralateral PPC was stimulated at 600ms. SI and PPC play sequential and distinct roles in neural processes of cross-modal associations and working memory.

Investigating the TACOM measure as a general tool for quantifying the complexity of procedure guided tasks

According to operation experience, it is evident that the role of human operators is critical for securing the safety of complex socio-technical systems. For this reason, various kinds of HRA (Human Reliability Analysis) techniques have been used for several decades in order to systematically manage the likelihood of human error. One of the prerequisites to accomplish this goal is the provision of sufficient data that are helpful for HRA practitioners. In this regard, Podofillini, Park, and Dang (2013) investigated the feasibility of the TACOM (Task Complexity) measure as a tool to represent the effect of a task complexity on the performance of human operators in an objective manner. As a result, it was observed that TACOM scores systematically explain the variation of difficulty rankings and the likelihood of human error being empirically measured. Accordingly, it is possible to expect that the TACOM measure can support HRA practitioners because they can estimate the relative difficulties (or the likelihoods of human error) among tasks based on the associated TACOM scores to some extent. In order to confirm this expectation, however, it is indispensable to ensure the generality of the TACOM measure. From this necessity, task performance time data obtained from different task environments are compared. Consequently, it is believed that the TACOM measure can be regarded as a general tool for representing the complexity of procedure guided tasks because human operators who are faced with similar TACOM scores showed comparable task performance times even under different task environments.