Physical-Layer Secret Key Generation for Dual-Task Scenarios

Physical-layer secret key generation(PSKG)provides a lightweight way for group key(GK)sharing between wireless users in large-scale wireless networks.However,most of the existing works in this field consider only group communication.For a commonly dual-task scenario,where both GK and pairwise key(PK)are required,traditional methods are less suitable for direct extension.For the first time,we discover a security issue with traditional methods in dual-task scenarios,which has not previously been recognized.We propose an innovative segment-based key generation method to solve this security issue.We do not directly use PK exclusively to negotiate the GK as traditional methods.Instead,we generate GK and PK separately through segmentation which is the first solution to meet dual-task.We also perform security and rate analysis.It is demonstrated that our method is effective in solving this security issue from an information-theoretic perspective.The rate results of simulation are also consistent with the our rate derivation.

Dual-Tasking as Diagnostic and Rehabilitation Tool in Traumatic Brain Injury Patients

Objective: Purpose of this study was to investigate the behavioral and brain activity impairments in patients after moderate traumatic brain injury (mTBI) in comparison with the normal ranges while dual-tasks performing. We would like to evaluate dual-tasking as diagnostic and rehabilitation tool and to test hypothesis of brain aging after mTBI. Material and Methods: Electroencephalographic (EEG), stabilographic and clinical study was performed in 11 patients (mean age 28.8 ± 8.4 years) for up to 1 - 12 months after a mTBI in comparison with 17 healthy subjects (26.7 ± 5.1 years). All the participants performed two motor and two cognitive tasks presented separately, and simultaneously (dual-tasking). Results: Clinical examination revealed predominantly cognitive deficit in mTBI patients with intact postural control. EEG data demonstrated coherence decrease for slow (delta-theta) rhythms in frontal-temporal areas predominantly for left hemisphere during cognitive tasks performance. In contrast, EEG coherence for slow spectral bands increased in the same areas in healthy volunteers. EEG coherence increased for fast spectral bands—alpha2 and beta, predominantly in right hemisphere while both healthy adults and patients performed motor components of dual tasks. Rehabilitation course with dual tasks, led to a predominant reduction in cognitive deficits, and EEG coherence increases at the frontal-temporal areas of the left hemisphere. Conclusions: Dual-tasks may be used as diagnostic tool in patients after mTBI. This approach demonstrates predominant cognitive deficit, and left hemispheric dysfunction in patients similar to elderly persons and support the hypothesis of brain aging after TBI. Pilot studies also suggested rehabilitation effect of dual-tasking in mTBI patients.

Interaction between semantic and phonological processes in stuttering Evidence from the dual-task paradigm

Stuttering is a common neurological deficit and its underlying cognitive mechanisms are a matter of debate, with evidence suggesting abnormal modulation between speech encoding and other cognitive components. Previous studies have mainly used single task experiments to investigate the disturbance of language production. It is unclear whether there is abnormal interaction between the three language tasks （orthographic, phonological and semantic judgment） in stuttering patients. This study used dual tasks and manipulated the stimulus onset asynchrony （SOA） between tasks 1 and 2 and the nature of the second task, including orthographic, phonological, and semantic judgments. The results showed that the performance records of orthographic judgment, phonological judgment, and semantic judgment were significantly reduced between the patient and control groups with short SOA （P 〈 0.05）. However, different patterns of interaction between task 2 and SOA were observed across subject groups： subjects with stuttering were more strongly modulated by SOA when the second task was semantic judgment or phonological judgment （P 〈 0.05）, but not in the orthographic judgment experiment （P 〉 0.05）. These results indicated that the interaction mechanism between semantic processing and phonological encoding might be an underlying cause for stuttering.

The Feasibility of a Novel Dual-Task Exercise Program Which Integrates Balance, Gaze, Mobility and Cognition in Community Dwelling Older Adults: Protocol for a Randomized Clinical Pilot Trial

Background: Mobility limitations and cognitive impairments which are common with ageing often coexist, causing a reduction in the levels of physical and mental activity and are prognostic of future adverse health events and falls. Consequently, multi-task training paradigms that simultaneously address both mobility and cognition benefit healthy ageing are important to consider in rehabilitation as well as primary prevention. Objectives: An exploratory RCT is being conducted to: a) describe the feasibility and acceptability of the study design and process, procedures, resources and management in two game-based dual-task training programs delivered in the community;b) to explore the lived experiences of the study participants who completed their respective exercise programs. A secondary objective is to obtain preliminary data on the therapeutic effectiveness of the two dual-task training programs. Methods: Thirty healthy older community dwelling participants aged 70 - 85 with previous history of falls will be recruited and randomized to either dual- task treadmill walking (experimental group) or dual-task recumbent bicycle (control group). Data analysis: The qualitative data will be analyzed by two investigators using a content analysis approach. For the quantitative data, outcome measures will be collected pre and post intervention and included measures to assess core balance, spatial-temporal gait variables, visual tracking and cognitive function, as well as, balance and gait analysis under dual-task conditions. Discussion: This research will demonstrate the feasibility of the dual-task training programs in the community, and demonstrate the system’s ability to improve targeted and integrated (dual-task) aspects of balance, mobility, gaze, and cognitive performance. A blended analysis of balance, mobility gaze and cognition will also contribute to a better understanding of the functional consequences of decline in physical and mental skills with age. Trial registration: This pilot clinical trial has been registered at ClinicalTrials.gov Protocol Registration System: NCT01940055.

Comparing the effects of dual-task training and single-task training on walking,balance and cognitive functions in individuals with Parkinson’s disease:A systematic review

Background:This systematic review aimed to examine whether dual-task(DT)training was superior to single-task(ST)training in improving DT walking,balance and cognitive functions for individuals with Parkinson’s disease(PD).Methods:Literature search was performed in the following electronic databases:PubMed,the Cochrane Library,Web of Science,and Metstr covering inception to May 10,2023.And in order to facilitate comparison across trials,we calculated the effect size(Hedges’g)of gait,balance,cognitive,and other parameters under both ST and DT conditions,using the mean change score and standard deviation(SD)of change score of the experimental and control groups.Randomized controlled trials that examined the effects of DT motor and cognitive training in individuals with Parkinson’s disease were included for this systematic review.Results:A total of 214 participants recruited from six articles(actually five trials)were involved in this review.In terms of walking ability,only double support time and stride time variability showed significant between-group difference(Hedges’g=0.34,0.18,respectively).Compared to ST training group,DT training group had a more improvement effect in laboratory balance measurement(Hedges’g=0.18,1.25),but no significant improvement in clinical balance measurement.No significant between-group differences were observed,thus its training effect on cognitive function was inconclusive.Conclusions:The DT training failed to achieve promising results better than ST training in improving DT walking and balance functions for individuals with PD.Any firm conclusion cannot be drawn at present,due to the limited number of eligible publications.Larger sample size and high-quality studies are needed to investigate the effectiveness of DT training in individuals with PD.

About the structure of posturography: Sampling duration, parametrization, focus of attention (part II)

There exists a great variety of posturographic parameters which complicates the evaluation of center of pressure (COP) data. Hence, recommendations were given to use a set of complementary parameters to explain most of the variance. However, it is unknown whether a dual task paradigm leads to different parametrization sets. On account of this problem an exploratory factor analysis approach was conducted in a dual task experiment. 16 healthy subjects stood on a force plate performing a posture-cognition dual task (DT, focus of attention on a secondary task) with respect to different sampling durations. The subjects were not aware of being measured in contrast to a baseline task condition (BT, internal focus of attention) in the previously published part I. In compareson to BT a different factor loading pattern appears. In addition, factor loadings are strongly affected by different sampling durations. DT reveals a change of factor loading structure with longer sampling durations compared to BT. Specific recommendations concerning a framework of posturographic parametrization are given.

Spatial orientation during eyes closed versus open in the dark: Are they the same?

We hypothesized that keeping one’s balance with eyes open in the dark is different and more difficult than eyes closed because the brain continues to process visual inputs in the dark when the eyes are open. On the other hand, when the eyes are closed, the visual system does not signal incongruent information with which the brain must compare the other sensory systems. A variety of cognitive (subtracting backwards by seven as quickly and accurately as possible) and support surface (fixed versus sway-referenced) conditions were used to probe the neural mechanisms underlying the sensory organization processes in healthy young adults. Peak-to-peak anteroposterior sway performance revealed two dissociated components of the treatment effects. The first component came from the visuospatial factor. Balance control during eye closure and eyes open in the dark were found to be similar but poorer than baseline condition (eyes open under typical lighting). The second component was the effect of task difficulty in which balance control in the sway-referenced condition was worse compared to fixed support during eye closure or eyes open in the dark. Analyses of the cognitive performance also revealed different underlying neural mechanisms of the experimental conditions. Subtraction speed under the fixed support surface condition was similar among all the conditions but was faster with eyes closed during the sway-referenced support surface condition. Accuracy was not affected among the visual and surface conditions. We conclude that sensory processing load with eyes closed is lower than eyes open in the dark, thereby allowing cognitive performance to proceed more efficiently. Performing a difficult subtraction task with eyes closed may afford a decrease in dual-task interference since similar brain areas, particularly the parietal region, are involved in both tasks. The results are discussed with reference to clinical application and spatial disorientation in aviation.

A Comparison of Central Sensory Reception and Integration Abilities between Older Females with and without Fibromyalgia: A Pilot Study

Purpose: Impaired postural control has been reported in females with fibromyalgia syndrome (FMS). This study aimed to investigate a) differences in central sensory reception and integration abilities for postural control between older females with and without FMS, and b) the influence of a secondary cognitive task on postural control in altered sensory environments. Methods: The performances of 10 older females with FMS were compared to eight age-matched healthy females across single and dual task conditions using the Sensory Organization Test&reg;. Results: No significant group differences were evident for Composite Equilibrium Score (CES) in the single task condition (p = 0.06) but a large effect size (Cohen’s d = 0.96) was obtained, suggesting a clinically relevant difference existed between groups with respect to general sensory reception and integration abilities. Single trial Equilibrium Scores (ESs) for both groups declined significantly in the more complex sensory conditions across both task conditions (p < 0.01) with a greater decline evident for the FMS group in sensory condition 4 in the dual-task condition (p = 0.04). The FMS group also experienced multiple falls in sensory conditions 5 and 6 across both task conditions with a significantly higher percentage of falls evident for the FMS group in condition 6 across both task conditions (p = 0.04). Conclusions: Overall postural stability was significantly lower in the FMS group when compared to an age-matched control group. Postural stability declined further in the FMS group when attempting to perform a secondary cognitive task in both sensory conditions that primarily relied on vestibular inputs for postural control. A greater focus on multisensory and dual-task training in a balance environment may benefit older females with FMS.

Case Study on Assessment of Mild Traumatic Brain Injury Using Granular Computing

Patients with mild traumatic brain injury complain about having balance and stability problems despite normal clinical examination. The objective of this study is to investigate the stride-to-stride gait variability of mTBI subjects while walking on treadmill under dual-task gait protocols. Fuzzy-granular computing algorithm is used to objectively quantify the stride-to-stride variability of temporal gait parameters. The degrees of similarity (DS) of temporal gait parameters in the dual tasks were determined from the corresponding granulated time-series. The mTBI group showed relatively smaller degree of similarity for all window sizes under the cognitive (dual) task walking, showing pronounced stride-to-stride variability. Different levels of DS among the mTBI subjects were observed. Individually, both healthy and mTBI group showed different DS under the two dual-tasks, reflecting the challenging level of the cognitive tasks while walking. The mean values of the temporal parameters for the mTBI group were different from the averaged normal reference. On the other hand, the individual variance analysis shows no significant differences between the normal and dual task values for some mTBI subjects. The granular approach however is able to reveal very fine differences and exhibited similar trends for all mTBI subjects. Different DS values among mTBI group could be indicative for the different severity level or the undergone rehabilitation process.

Dual-task training to improve cognitive impairment and walking function in Parkinson's disease patients:A brief review

In daily functional activities,the body needs the ability to perform two or more tasks at the same time(such as talking while walking).However,the gait disorder of patients with Parkinson's disease is aggravated when performing dual tasks,which seriously affects their quality of life.Therefore,the medical management plan should offer effective exercise training programming to improve Parkinson's disease patients'ability to perform dual tasks.Most traditional exercise intervention methods only focus on the perspective of exercise or cognition,ignoring their interaction,and fail to adequately resolve the dual task obstacles associated with Parkinson's disease.Some scholars put forward the concept of dual-task training and have applied dual-task training to pa-tients with neurological disorders and have achieved good therapeutic effects.Therefore,this article summarizes the research literature concerning dual-task training to improve cognitive impairment and walking function of Parkinson's disease patients,to evaluate and discuss possible mechanisms of action,and provide a basis for adjuvant treatment and rehabilitation of Parkinson's disease patients.

Noninvasive Assessment of Liver Fibrosis and Inflammation in Chronic Hepatitis B:A Dual-task Convolutional Neural Network(DtCNN)Model Based on Ultrasound Shear Wave Elastography

Background and Aims:Liver stiffness(LS)measured by shear wave elastography(SWE)is often influenced by hepat-ic inflammation.The aim was to develop a dual-task convo-lutional neural network(DtCNN)model for the simultaneous staging of liver fibrosis and inflammation activity using 2D-SWE.Methods:A total of 532 patients with chronic hepatitis B(CHB)were included to develop and validate the DtCNN model.An additional 180 consecutive patients between De-cember 2019 and April 2021 were prospectively included for further validation.All patients underwent 2D-SWE examina-tion and serum biomarker assessment.A DtCNN model con-taining two pathways for the staging of fibrosis and inflam-mation was used to improve the classification of significant fibrosis(≥F2),advanced fibrosis(≥F3)as well as cirrhosis(F4).Results:Both fibrosis and inflammation affected LS measurements by 2D-SWE.The proposed DtCNN performed the best among all the classification models for fibrosis stage[significant fibrosis AUC=0.89(95%CI:0.87-0.92),ad-vanced fibrosis AUC=0.87(95%CI:0.84-0.90),liver cirrho-sis AUC=0.85(95%CI:0.81-0.89)].The DtCNN-based pre-diction of inflammation activity achieved AUCs of 0.82(95%CI:0.78-0.86)for grade≥A1,0.88(95%CI:0.85-0.90)grade≥A2 and 0.78(95%CI:0.75-0.81)for grade≥A3,which were significantly higher than the AUCs of the single-task groups.Similar findings were observed in the prospec-tive study.Conclusions:The proposed DtCNN improved di-agnostic performance compared with existing fibrosis staging models by including inflammation in the model,which sup-ports its potential clinical application.

Validation of the Wii Balance Board to assess static balance during dual-task activity in healthy subjects

Objective:Although dual-task paradigm is commonly used in rehabilitation there is,currently,a lack of information about quantitative balance assessment performed in dual-task conditions.The aim of this study is to validate the use of the Nintendo Wii Balance Board(WBB)to assess balance modifications induced by dual-task activity in healthy subjects.Material and methods:Seventy-five healthy participants(37±14 years old,173±8 cm,73
16 kg,35 women)participated in this study.Balance was recorded in control situation(baseline)and under two different cognitive tasks(verbal fluency and calculation).Each trial lasted for 60 s and were performed with eyes open and closed.Nine parameters were extracted based on center of pressure displacement based on a previously-validated method.ANOVA tests were used to compare the different conditions followed by Bonferroni’s corrections.Protocol was repeated one week after to assess the reproducibility.Results:Statistically significant differences were found comparing eyes open and closed situation.Concerning the influence of dual-tasks statistically significant decrease of the balance was observed for both eyes open and closed conditions(increase of the total sway and the speed of displacement).Concerning the reproducibility all parameters shows good to excellent ICC values for the different conditions.Conclusion:In this study,we demonstrated the validity of the WBB to detect the effect of the dual-task on balance in healthy subjects.Further studies are needed to determine if such a kind of evaluation can be used in clinics with subjects at risk of falling.