The separate neural control of hand movements and contact forces

To manipulate an object, we must simultaneously control the contact forces exerted on the object and the movements of our hand. Two alternative views for manipulation have been proposed: one in which motions and contact forces are represented and controlled by separate neural processes, and one in which motions and forces are controlled jointly, by a single process. To evaluate these alternatives, we designed three tasks in which subjects maintained a specified contact force while their hand was moved by a robotic manipulandum. The prescribed contact force and hand motions were selected in each task to induce the subject to attain one of three goals: (1) exerting a regulated contact force, (2) tracking the motion of the manipulandum, and (3) attaining both force and motion goals concurrently. By comparing subjects' performances in these three tasks, we found that behavior was captured by the summed actions of two independent control systems: one applying the desired force, and the other guiding the hand along the predicted path of the manipulandum. Furthermore, the application of transcranial magnetic stimulation impulses to the posterior parietal cortex selectively disrupted the control of motion but did not affect the regulation of static contact force. Together, these findings are consistent with the view that manipulation of objects is performed by independent brain control of hand motions and interaction forces

Learning Redundant Motor Tasks With and Without Overlapping Dimensions: Facilitation and Interference Effects

Prior learning of a motor skill creates motor memories that can facilitate or interfere with learning of new, but related, motor skills. One hypothesis of motor learning posits that for a sensorimotor task with redundant degrees of freedom, the nervous system learns the geometric structure of the task and improves performance by selectively operating within that task space. We tested this hypothesis by examining if transfer of learning between two tasks depends on shared dimensionality between their respective task spaces. Human participants wore a data glove and learned to manipulate a computer cursor by moving their fingers. Separate groups of participants learned two tasks: a prior task that was unique to each group and a criterion task that was common to all groups. We manipulated the mapping between finger motions and cursor positions in the prior task to define task spaces that either shared or did not share the task space dimensions (x-y axes) of the criterion task. We found that if the prior task shared task dimensions with the criterion task, there was an initial facilitation in criterion task performance. However, if the prior task did not share task dimensions with the criterion task, there was prolonged interference in learning the criterion task due to participants finding inefficient task solutions. These results show that the nervous system learns the task space through practice, and that the degree of shared task space dimensionality influences the extent to which prior experience transfers to subsequent learning of related motor skills

Sensory Motor Remapping of Space in Human-Machine Interfaces

Studies of adaptation to patterns of deterministic forces have revealed the ability of the motor control system to form and use predictive representations of the environment. These studies have also pointed out that adaptation to novel dynamics is aimed at preserving the trajectories of a controlled endpoint, either the hand of a subject or a transported object. We review some of these experiments and present more recent studies aimed at understanding how the motor system forms representations of the physical space in which actions take place. An extensive line of investigations in visual information processing has dealt with the issue of how the Euclidean properties of space are recovered from visual signals that do not appear to possess these properties. The same question is addressed here in the context of motor behavior and motor learning by observing how people remap hand gestures and body motions that control the state of an external device. We present some theoretical considerations and experimental evidence about the ability of the nervous system to create novel patterns of coordination that are consistent with the representation of extrapersonal space. We also discuss the perspective of endowing human–machine interfaces with learning algorithms that, combined with human learning, may facilitate the control of powered wheelchairs and other assistive devices

Assessing the Contribution of Mobile Phone Agricultural Information on Maize Productivity: A Case Study of Kilolo District, Tanzania

The purpose of this study is to investigate the contribution of mobile phone agricultural information on maize productivity among smallholder farmers in Kilolo District while taking into consideration contextual factors that may affect the efficacy of such interventions. By analyzing the potential benefits associated with the dissemination of agricultural information via mobile phones, this study aims to significantly contribute to the academic conversation and practical interventions focused on sustainable agricultural growth in the region. In this study, a cross-sectional strategy was employed as a general framework for the research design process. This study employed a quantitative research strategy. To gather quantitative information about smallholder farmers' ownership of mobile phones, usage habits, access to agricultural information, and productivity in growing maize,the target population comprises 106,342 farmers and selected sample of 173 farmers in Kilolo District was surveyed. From the findingsIt is also established in the study that 89% of the respondents agreed that accessed information helped in improving their market management while 11% disagreed, Also 60%) of the respondents agreed that there are increased yields in maize farming due to information accessed through mobile phones, (54%) of the respondents agreed that the advantages of agricultural information accessed through mobile phones on maize productivity outweigh the drawbacks, it was established that (78%) of the respondents agreed that they had changed their maize farming practices based on the agricultural information accessed through mobile (69%) of the respondents agreed that the impact of the agricultural information accessed through mobile phones positively affects maize productivity. The study's findings highlight the important positive contribution that mobile phone agriculture information has had on smallholder farmers in Kilolo District's maize productivity. It is established that both smart and non-smart mobile phones act as a link between farmers and consumers. By fostering informed decision-making, enhancing pest management, and enabling market contact, mobile phone interventions have the potential to greatly improve farmers' livelihoods and increase food security in the region. To maximize the benefits of these interventions and promote sustainable agricultural growth, it will be critical to address the barriers and provide fair and equal access.&nbsp

A review on the use of Information Communication Technology (ICT) in fisheries management: A case of Mbenji Island small-scale fishery in Malawi

Fisheries management has evolved in Malawi from a traditional system to a centralized regime and lately to co-management fisheries systems, although, success stories about sustainability of the fishery resources are few. Open access nature of fisheries resources has posed a challenge to management regimes. Resource overexploitation has continued in a majority of fisheries worsened by large stretches of the shoreline manned by a single fisheries field staff, and limited capacity by DoF to monitor and manage the fishery. However, isolated localities have upheld management styles that have facilitated sustainable exploitation. Mbenji Island fishery ‘managers’ have ensured high compliance to fisheries rules and regulations among fishers through strict enforcement and maintained abundant fish stocks amid visibly declining levels of fish in vast localities of Lake Malawi and other water bodies in Malawi. There is, therefore, need to take the Mbenji Island success story to other fishing communities to learn from their fisheries management strategies. Information Communication Technology (ICT) as a powerful means in mobilizing communities to take charge of their own development should support ‘best practices’ and offer fishing communities access to the same type of services and advantages. If appropriately applied, ICT can provide for real-time monitoring of fisheries resources as fishers alarm law enforcers to move in at appropriate times. Fishers also strike deals on mobile phones for the day's catch even before landing at shore. This reduces post-harvest waste from delayed handling of fish. Computers have been used for data management, storage and analysis as well as accessing internet services. Studies have shown commonalities in fisher communities in terms of socio-economic and cultural characteristics. On the basis of such an advantage, more could be shared among such communities. Management success can be adopted by other communities of fishers through use of ICT such as radio programs (supplemented by phone-in sessions) undertaken by local-level resource users. These programs provide locally available information and knowledge on best practices aimed at sustainability with means within communities. This encourages community members in other localities to come together to seek the way forward on the basis of lessons from successful communities aired on local radio stations (both community or national radio stations). It is easier to adopt practices that have worked in near vicinities. After all, what is currently called comanagement is seemingly based on indigenous knowledge of fishers and other resource users. Mbenji Island is one of the custodians of ICT option in small-scale fisheries management of Lake Malawi. Information Communication Technology provides opportunity for both the Malawi Department of Fisheries (DoF) and fishers with information about fisher community activities including catch and market regardless of distance.&nbsp

Exploring Carrier Sense Multiple Access with Collision Avoidance Techniques for Resource Sharing in Broadband Power Line Communications

A resource sharing in power line communications (PLC) for the home network is restricted by the channel assignment techniques which decide who has the right to gain access to send data. The channel assignment techniques include contention-free and contention-based. The former requires high synchronization due to the deterministic round-trip time. Besides, contention-based utilizes CSMA/CA techniques that allow stations in a network to compete for channel access and are suitable for decentralized network topology. However, a trade-off exists between the number of stations required to gain access versus system efficiency. Whilst some research has been carried out on CSMA/CA resource sharing techniques that allow only one user to transmit, there is very little work done on multiuser access to optimize system efficiency and reduce collisions in a network. The purpose of the current study was to review the CSMA/CA techniques for resource sharing to improve system efficiency in power line communications. In carrying out this study, a systematic literature review methodology to evaluate different related works and determine the most suitable approach to allow multiuser channel access was used. The study further demonstrated the impact multichannel access has on system efficiency. In addition, the study provides recommendations for future research. Keywords: CSMA/CA; Medium access control; OFDMA; power line; resource sharing